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<document ID-CLB-Dataset="284056" ID-DOI="http://dx.doi.org/10.3897/fr.27.115046" ID-GBIF-Dataset="61da7871-d1a3-4645-ad73-cd67ae12e047" ID-Pensoft-Pub="2193-0074-1-13" ID-Pensoft-UUID="E66E9A52FB9F5578989FD82293A4468E" ID-ZooBank="EB036D6DC69E4741845B748FD9C47065" ModsDocID="2193-0074-27-1-13" checkinTime="1704420692152" checkinUser="pensoft" docAuthor="Rollot, Yann, Evers, Serjoscha W. &amp; Joyce, Walter G." docDate="2024" docId="48FAF768B0F8589FABB5F70EB55C437C" docLanguage="en" docName="FossilRecord 27(1): 13-28" docOrigin="Fossil Record 27 (1)" docPubDate="2024-01-04" docSource="http://dx.doi.org/10.3897/fr.27.115046" docTitle="Allaeochelys libyca Havlik et al. 2014" docType="treatment" docVersion="4" id="E66E9A52FB9F5578989FD82293A4468E" lastPageNumber="13" masterDocId="E66E9A52FB9F5578989FD82293A4468E" masterDocTitle="A digital redescription of the Middle Miocene (Langhian) carettochelyid turtle Allaeochelys libyca" masterLastPageNumber="28" masterPageNumber="13" pageNumber="13" updateTime="1732846390213" updateUser="ExternalLinkService">
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<mods:titleInfo id="E6C2E7EBCDEA3BB7F32F6E7D24F450F8">
<mods:title id="55351158E1D30BE6554AB735DAE1F227">A digital redescription of the Middle Miocene (Langhian) carettochelyid turtle Allaeochelys libyca</mods:title>
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<mods:name id="74751070DFE4CC3BD4BF6C847B6FF9B1" type="personal">
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<mods:namePart id="DBCA860876F34AC126DD47BF74E5AC41">Rollot, Yann</mods:namePart>
<mods:nameIdentifier id="085AB79578BB3168FCCE1A6266914FCD" type="ORCID">https://orcid.org/0000-0002-2020-9456</mods:nameIdentifier>
<mods:affiliation id="A83A82419C02193F3F1BCE3E5E2299CC">Chemin du Musee 6, Department of Geosciences, University of Fribourg, Fribourg, Switzerland</mods:affiliation>
<mods:nameIdentifier id="75971EEE48D35759EEF78CFD5A6F7529" type="email">yann.rollot@gmail.com</mods:nameIdentifier>
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<mods:namePart id="D12C1B5707C8F22F6621E0A6C939B82F">Evers, Serjoscha W.</mods:namePart>
<mods:nameIdentifier id="FB7F51AF343DF72864F836948DD62CB9" type="ORCID">https://orcid.org/0000-0002-2393-5621</mods:nameIdentifier>
<mods:affiliation id="3CB592A86328B81EDABBC82F690C9321">Chemin du Musee 6, Department of Geosciences, University of Fribourg, Fribourg, Switzerland</mods:affiliation>
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<mods:namePart id="E0A1CA0CE58EEFF1E347F8EEC0328671">Joyce, Walter G.</mods:namePart>
<mods:nameIdentifier id="3685B11E74AD0A75ED0BB31413E39EF5" type="ORCID">https://orcid.org/0000-0003-4726-2449</mods:nameIdentifier>
<mods:affiliation id="E43C0D1748890C970C8514C00FFBA026">Chemin du Musee 6, Department of Geosciences, University of Fribourg, Fribourg, Switzerland</mods:affiliation>
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<mods:title id="43EDCCE8A5CDDA02A9870D4ED450A27E">Fossil Record</mods:title>
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<mods:date id="FFFA7681DE43C7F0DE649AA55ADBE181">2024</mods:date>
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<mods:number id="5C75552ABC63EE6AFD07DDF1B26FAF15">2024-01-04</mods:number>
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<mods:number id="CA20A23B1CDFEEFA16A93601D30381BD">27</mods:number>
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<mods:number id="D47F30271EC6E90B8366D7F8D0362B90">1</mods:number>
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<mods:start id="4994CBDCAE45425B2204828299BC8507">13</mods:start>
<mods:end id="3FA146E93A8850275B86960DF40F6511">28</mods:end>
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<treatment id="48FAF768B0F8589FABB5F70EB55C437C" ID-GBIF-Taxon="220564189" LSID="urn:lsid:plazi:treatment:48FAF768B0F8589FABB5F70EB55C437C" httpUri="http://treatment.plazi.org/id/48FAF768B0F8589FABB5F70EB55C437C" lastPageNumber="13" pageId="0" pageNumber="13" scope_family="Carettochelyidae" scope_order="Testudines" scope_subOrder="Trionychia">
<subSubSection id="1310D75292692409EFB1EA1ADBA885EE" pageId="0" pageNumber="13" type="nomenclature">
<paragraph id="231C468555063581B8C34B6EC62584F8" pageId="0" pageNumber="13">
<taxonomicName id="2E1B0C550D08A94202B9B4A5A962DF12" LSID="48FAF768-B0F8-589F-ABB5-F70EB55C437C" authority="Havlik et al., 2014" authorityName="Havlik et al." authorityYear="2014" family="Carettochelyidae" genus="Allaeochelys" higherTaxonomySource="treatment-meta" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">Allaeochelys libyca Havlik et al., 2014</taxonomicName>
</paragraph>
</subSubSection>
<subSubSection id="3FEDDB0D8A0C363C3028290584D81C5A" pageId="0" pageNumber="13" type="holotype">
<paragraph id="8F1175F840ECB487257AB74354BF8547" pageId="0" pageNumber="13">Holotype.</paragraph>
<paragraph id="BCBA5B9FEDC70877BBD2C644E8939843" pageId="0" pageNumber="13">BSPG 1991 II 130, an incomplete cranium.</paragraph>
</subSubSection>
<subSubSection id="46053EDF23BF86474E8E2E9636ACBE57" pageId="0" pageNumber="13" type="materials_examined">
<paragraph id="BCE47638EA3C89C1640197A114F52FF6" pageId="0" pageNumber="13">Referred material.</paragraph>
<paragraph id="837626106524A110BD1B1BA10EF1554A" pageId="0" pageNumber="13">
BSPG
<date id="3A68261B762842056E197CF5AA7FB61C" value="1991-02">1991 II</date>
96, a left hypoplastron; BSPG
<date id="B0428CB9DE46B13F0DCE75F9042A6903" value="1991-02">1991 II</date>
97, a left hypoplastron; BSPG
<date id="68DC7654D22CB1BE63ED0E026EFD8BE3" value="1991-02">1991 II</date>
110, a bridge peripheral; BSPG
<date id="73EFB738F3D1AAC8B24D32A8A049FF67" value="1991-02">1991 II</date>
113, an anterior peripheral; BSPG
<date id="80752687580EEFB70DE56A1B913B9D93" value="1991-02">1991 II</date>
114, a peripheral I; BSPG
<date id="267B27F8587B4A57CB7329F1D7974578" value="1991-02">1991 II</date>
131, an incomplete supraoccipital.
</paragraph>
</subSubSection>
<subSubSection id="B41A069DA2529541E40C8D33A185612C" pageId="0" pageNumber="13" type="type locality">
<paragraph id="07632AA7F458CC0F9D55BB3A73A872EB" pageId="0" pageNumber="13">Type locality and horizon.</paragraph>
<paragraph id="AF8BF56F72D989F8E8E42D0C17700A90" pageId="0" pageNumber="13">
Gebel Zelten (Jabal Zaltan), southwestern slopes, localities &quot;MS 2&quot; or &quot;Wadi Shatirat,&quot; Al Wahat District, Libya (
<bibRefCitation id="CF161F52311CCEB79323562A1B35C24F" author="Wessels, W" journalOrPublisher="Coloquios de Paleontologia" pageId="0" pageNumber="13" pagination="699 - 715" refId="B55" refString="Wessels, W, Fejfar, O, Pelaez-Campomanes, P, van der Meulen, A, de Bruijn, H, 2003. Miocene small mammals from Jebel Zelten, Libya. Coloquios de Paleontologia 1: 699 - 715" title="Miocene small mammals from Jebel Zelten, Libya." volume="1" year="2003">Wessels et al. 2003</bibRefCitation>
). Lower Maradah Formation, Middle Miocene, Langhian (
<bibRefCitation id="66A8420D7B95E195B00B2DF3B6AF0F3E" author="Desio, A" journalOrPublisher="Missione scientifica della Reale Accademia d'Italia a Cufra" pageId="0" pageNumber="13" pagination="1 - 464" refId="B13" refString="Desio, A, 1935. Studi geologici sulla Sirenaica, sul deserto Libico, sulla Tripolitania e sulle Fezzan orientali. Missione scientifica della Reale Accademia d'Italia a Cufra 1: 1 - 464" title="Studi geologici sulla Sirenaica, sul deserto Libico, sulla Tripolitania e sulle Fezzan orientali." volume="1" year="1935">Desio 1935</bibRefCitation>
;
<bibRefCitation id="545BE6B5F5862638BCB16D162C4B4295" author="Wessels, W" journalOrPublisher="Coloquios de Paleontologia" pageId="0" pageNumber="13" pagination="699 - 715" refId="B55" refString="Wessels, W, Fejfar, O, Pelaez-Campomanes, P, van der Meulen, A, de Bruijn, H, 2003. Miocene small mammals from Jebel Zelten, Libya. Coloquios de Paleontologia 1: 699 - 715" title="Miocene small mammals from Jebel Zelten, Libya." volume="1" year="2003">Wessels et al. 2003</bibRefCitation>
).
</paragraph>
</subSubSection>
<subSubSection id="A522026D5C2014B70294CA7700F1F957" pageId="0" pageNumber="13" type="revised diagnosis">
<paragraph id="465CD2A9EC0C4BF2A4CFE06FDA7444D7" pageId="0" pageNumber="13">Revised diagnosis.</paragraph>
<paragraph id="FE85523959123139FC86DDF25AEE9B37" pageId="0" pageNumber="13">
<taxonomicName id="7E4E79757032485813BB0AB1364C447D" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="6D198342CADCB1D0E64A4180781E0B53" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
can be diagnosed as a representative of
<taxonomicName id="3C821B0305822C5B227933EC9117AEE2" class="Testudines" family="Carettochelyidae" kingdom="Animalia" lsidName="" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="family">Carettochelyidae</taxonomicName>
based on its dermal ornamentation made of thick ridges separated by equally sized grooves, presence of a deep fossa on the posterior surface of the quadrate, and a reduced antrum postoticum and a member of
<taxonomicName id="D9D9A2945BFA7667E0E0B8854F711348" lsidName="" pageId="0" pageNumber="13" rank="subFamily" subFamily="Carettochelyinae">Carettochelyinae</taxonomicName>
based on the absence of carapacial and plastral scutes and the presence of a broad plastron.
<taxonomicName id="A2264D2A66B6F7B30906B1E2B2DEAF13" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="16BCBC825B882DC02CE522ECEE16C148" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
can be differentiated from
<taxonomicName id="C037CC6E3D42F15B9BEBD3B8DD35CB91" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="E0B10879F0399F32522CBA247E4B445E" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
by having a broader and shorter cranium, a secondary contact between the prefrontal and frontal within the orbit, a more posteriorly located foramen posterius canalis carotici interni close to the fenestra postotica, a larger contribution of the opisthotic to the tubercula basioccipitale, a deeper pterygoid fossa, a larger quadrate fossa, a deeper sulcus between the mandibular condyles, a reduced canalis cavernosus, and absence of the sulcus cavernosus.
<taxonomicName id="9D8495DAC94C9CA24F417CA1A122867A" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="208A052D2D6BEF17C680E14985B3F05A" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
resembles
<taxonomicName id="8A2B3902930C3F5370102181A292C1B8" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys niahensis" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="niahensis">
<emphasis id="7739A6C5ADD381F9F54B30189A848959" italics="true" pageId="0" pageNumber="13">Carettochelys niahensis</emphasis>
</taxonomicName>
by having a secondary contact between the prefrontal and frontal, but appears to have an even broader skull.
</paragraph>
</subSubSection>
<subSubSection id="02F48CA5B854E06949D2E74F43A0C1E8" pageId="0" pageNumber="13" type="description and comparisons of the cranium of allaeochelys libyca">
<paragraph id="C796FB55BB64CF42274966465DE28751" pageId="0" pageNumber="13">
Description and comparisons of the cranium of
<taxonomicName id="B4DADF92E95E3EFD3D4CF58E9D160559" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="6788BC31713B47FDD031951B509FFB64" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
</paragraph>
<paragraph id="2415A647CFDA522594C7DFAE4CAD02BF" pageId="0" pageNumber="13">
<emphasis id="C4315C93396E02D7A3EEA557E121AB08" bold="true" pageId="0" pageNumber="13">General comments.</emphasis>
The cranium of BSPG 1991 II 130, the holotype of
<taxonomicName id="D4872B2A73371074589E82BED4F557F0" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="52E4DE23BF1414E2132A57E23F48AE62" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
, lacks most of its anteroventral and ventrolateral portions (Fig.
<figureCitation id="FA7E6EE9E9EEA3790976E695B2F81C76" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1</figureCitation>
). The premaxillae, maxillae, jugals, vomer, epipterygoids, and squamosals are not preserved. The palatines and postorbitals are almost completely lacking as well, and only small pieces of bone belonging to the most posterior and most medial portions of the right palatine and left postorbital, respectively, remain attached to the cranium. The prefrontals, frontals, parietals, pterygoids, parabasisphenoid, supraoccipital, and opisthotics lack substantial amounts of their original anatomy, whereas the prootics, quadrates, and basioccipital suffer from minor signs of damage. The exoccipitals are the only bones that are fully preserved.
</paragraph>
<caption id="45E79B708FC1B90EBC47F0B070C14A07" doi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13" start="Figure 1" startId="F1">
<paragraph id="52461A425DF87E192021E38461E7EDA3" pageId="0" pageNumber="13">
<emphasis id="340842DE04E08284A5B1C45DB28CC69B" bold="true" pageId="0" pageNumber="13">Figure 1.</emphasis>
Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113.
<emphasis id="C1F77BFAE9BBF58C08B41D54A11D3E84" bold="true" pageId="0" pageNumber="13">A.</emphasis>
Dorsal view;
<emphasis id="9DC19BE8DC045F1A3DA2B5CB077C31A3" bold="true" pageId="0" pageNumber="13">B.</emphasis>
Ventral view;
<emphasis id="E5DE69D86CCEF343709726BBB3B2BC42" bold="true" pageId="0" pageNumber="13">C.</emphasis>
Left lateral view;
<emphasis id="FE7955D776FBE4372FA7E41607FF85DF" bold="true" pageId="0" pageNumber="13">D.</emphasis>
Right lateral view;
<emphasis id="DA8A54366F1FCF93C7E64F938FA5FC64" bold="true" pageId="0" pageNumber="13">E.</emphasis>
Anterior view;
<emphasis id="85523CDFA22BA1FF43E31D134FB2D054" bold="true" pageId="0" pageNumber="13">F.</emphasis>
Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in
<emphasis id="06E95F35F06F6439D076E8D3688BEDB2" bold="true" pageId="0" pageNumber="13">A</emphasis>
, the passage between the orbit and nasal cavity in
<emphasis id="94F8B455F2BEE0024709ECE3C1181CB8" bold="true" pageId="0" pageNumber="13">B</emphasis>
, and the mandibular artery foramen in
<emphasis id="5EC5BAD69FD8AE8C9EB338A5E0D40C9C" bold="true" pageId="0" pageNumber="13">E</emphasis>
.
</paragraph>
</caption>
<paragraph id="2A2E906278560D5A0FDBAA45D226C9F1" pageId="0" pageNumber="13">
The preserved portions of the skull roof highlight the presence of the characteristic carettochelyid skull sculpturing, made of thick ridges separated by equally sized grooves (Fig.
<figureCitation id="65424EBDF7BEC9B8C82C2F66E2BB8976" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1</figureCitation>
). As in all carettochelyids (see
<bibRefCitation id="46820B168986AE3A27107F825BD53F4A" DOI="https://doi.org/10.1086/275045" author="Baur, G" journalOrPublisher="American Naturalist" pageId="0" pageNumber="13" pagination=": 1017" refId="B5" refString="Baur, G, 1889. Note on Carettochelys, Ramsay. American Naturalist 23 (275): 1017, DOI: https://doi.org/10.1086/275045" title="Note on Carettochelys, Ramsay." url="https://doi.org/10.1086/275045" volume="23" year="1889">Baur 1889</bibRefCitation>
;
<bibRefCitation id="140A17C5891320E49D0C97B5D8BCB1E7" author="Harrassowitz, H" journalOrPublisher="Abhandlungen der Hessischen Geologischen Landesanstalt" pageId="0" pageNumber="13" pagination="132 - 239" refId="B25" refString="Harrassowitz, H, 1922. Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung. Abhandlungen der Hessischen Geologischen Landesanstalt 6: 132 - 239" title="Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung." volume="6" year="1922">Harrassowitz 1922</bibRefCitation>
;
<bibRefCitation id="B02851BEE4160BF0729CBCE7B5C0975A" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="18165467CECFBE4FED77AE9A2E8FD28A" DOI="https://doi.org/10.3374/014.055.0102" author="Joyce, WG" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="3 - 33" refId="B28" refString="Joyce, WG, 2014. A review of the fossil record of turtles of the clade Pan-Carettochelys. Bulletin of the Peabody Museum of Natural History 55 (1): 3 - 33, DOI: https://doi.org/10.3374/014.055.0102" title="A review of the fossil record of turtles of the clade Pan-Carettochelys." url="https://doi.org/10.3374/014.055.0102" volume="55" year="2014">Joyce 2014</bibRefCitation>
;
<bibRefCitation id="97F2679C9A012C5C855D01D126B915A0" DOI="https://doi.org/10.1080/02724634.2017.1335735" author="Danilov, IG" journalOrPublisher="Geologische und Palaeontologische Abhandlungen" pageId="0" pageNumber="13" refId="B12" refString="Danilov, IG, Obraztsova, EM, Chen, W, Jianhua, J, 2017. The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37(4): e1335735. https://doi.org/10.1080/02724634.2017.1335735" title="The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37 (4): e 1335735." url="https://doi.org/10.1080/02724634.2017.1335735" year="2017">Danilov et al. 2017</bibRefCitation>
;
<bibRefCitation id="1517DCFC22BCDC621BC850C143A705C5" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
;
<bibRefCitation id="F6735AEB843CD5DF742F0958F36D7BD7" DOI="https://doi.org/10.1080/03115518.2023.2243503" author="White, AW" journalOrPublisher="Alcheringa: An Australasian Journal of Palaeontology" pageId="0" pageNumber="13" pagination="1 - 10" refId="B56" refString="White, AW, Archer, M, Hand, SJ, Godthelp, H, Gillespie, AK, 2023. A new broad-snouted fossil carettochelyid turtle from a previously unknown Caenozoic deposit in Sarawak, Malaysia. Alcheringa: An Australasian Journal of Palaeontology 47 (2): 1 - 10, DOI: https://doi.org/10.1080/03115518.2023.2243503" title="A new broad-snouted fossil carettochelyid turtle from a previously unknown Caenozoic deposit in Sarawak, Malaysia." url="https://doi.org/10.1080/03115518.2023.2243503" volume="47" year="2023">White et al. 2023</bibRefCitation>
), the upper temporal emargination is deep, the supraoccipital is posteriorly expanded by means of a well-developed crista supraoccipitalis and horizontal plate, the incisura columella auris is fully enclosed by the quadrate, the mandibular condyle is low, the palatines posteriorly contact the parabasisphenoid and fully separate the pterygoids, and the quadrate is posteriorly excavated by a fossa. The cranium is more robust and less gracile than that of
<taxonomicName id="B143093E3443A4B6515D2782940393F4" baseAuthorityName="Clark" baseAuthorityYear="1932" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira pulchra" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="pulchra">
<emphasis id="E08D44C7AC7B1DB77CB329C5382EA4D1" italics="true" pageId="0" pageNumber="13">Anosteira pulchra</emphasis>
</taxonomicName>
(
<bibRefCitation id="21CA11E17F3AE6478EF60BE75383C31B" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
), but broader than
<taxonomicName id="6E2F6D8BE7B779291D2B81C39A93EB2B" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="93D5C749EED8B311CCA85FD70DDCBFFC" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
(
<bibRefCitation id="99AA8C16ACD7C65B7C68A85ECB8C6331" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
). Although comparisons are difficult, proportions seem to be similar to
<taxonomicName id="21C6FBCE2CAEBDE4F3755CCD64B2D280" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys niahensis" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="niahensis">
<emphasis id="62F9C544A485A5FA71C6E89D705B364E" italics="true" pageId="0" pageNumber="13">Carettochelys niahensis</emphasis>
</taxonomicName>
(
<bibRefCitation id="9107DBBC325B09D75AF06C30409B1349" DOI="https://doi.org/10.1080/03115518.2023.2243503" author="White, AW" journalOrPublisher="Alcheringa: An Australasian Journal of Palaeontology" pageId="0" pageNumber="13" pagination="1 - 10" refId="B56" refString="White, AW, Archer, M, Hand, SJ, Godthelp, H, Gillespie, AK, 2023. A new broad-snouted fossil carettochelyid turtle from a previously unknown Caenozoic deposit in Sarawak, Malaysia. Alcheringa: An Australasian Journal of Palaeontology 47 (2): 1 - 10, DOI: https://doi.org/10.1080/03115518.2023.2243503" title="A new broad-snouted fossil carettochelyid turtle from a previously unknown Caenozoic deposit in Sarawak, Malaysia." url="https://doi.org/10.1080/03115518.2023.2243503" volume="47" year="2023">White et al. 2023</bibRefCitation>
). A unique feature exhibited by the cranium of
<taxonomicName id="EB47E58F71D5D6CD6EA92AFE2E8BDD1E" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="FF5B5C7C0834EA6FA92EAF29823A8B2E" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
is the complete reduction of the sulcus cavernosus, which is accompanied by a particular morphology of the trigeminal nerve foramen area.
</paragraph>
<paragraph id="AC6507FB97AE1218597C31E008CD0447" pageId="0" pageNumber="13">
The &quot;trigeminal foramen&quot; of turtles is somewhat of a misnomer, as only two of three of the trigeminal nerve rami exit this passage (
<bibRefCitation id="76C148C47A5110AEA553E0E3C19C55C3" DOI="https://doi.org/10.1093/zoolinnean/zlz063" author="Evers, SW" journalOrPublisher="Zoological Journal of the Linnean Society" pageId="0" pageNumber="13" pagination="800 - 828" refId="B16" refString="Evers, SW, Neenan, JM, Ferreira, GS, Werneburg, I, Barrett, PM, Benson, RB, 2019. Neurovascular anatomy of the protostegid turtle Rhinochelys pulchriceps and comparisons of membranous and endosseous labyrinth shape in an extant turtle. Zoological Journal of the Linnean Society 187 (3): 800 - 828, DOI: https://doi.org/10.1093/zoolinnean/zlz063" title="Neurovascular anatomy of the protostegid turtle Rhinochelys pulchriceps and comparisons of membranous and endosseous labyrinth shape in an extant turtle." url="https://doi.org/10.1093/zoolinnean/zlz063" volume="187" year="2019">Evers et al. 2019</bibRefCitation>
). The foramen instead is a lateral window from the outside into the region of the sulcus cavernosus, through which said nerve rami pass in addition to the mandibular artery of some groups of turtles (
<bibRefCitation id="A0FCAD66F1A6A1447868763F624BFB32" author="Albrecht, PW" journalOrPublisher="Tulane Studies in Zoology" pageId="0" pageNumber="13" pagination="81 - 99" refId="B1" refString="Albrecht, PW, 1967. The cranial arteries and cranial arterial foramina of the turtle genera Chrysemys, Sternotherus, and Trionyx: a comparative study with analysis of possible evolutionary implications. Tulane Studies in Zoology 14 (3): 81 - 99" title="The cranial arteries and cranial arterial foramina of the turtle genera Chrysemys, Sternotherus, and Trionyx: a comparative study with analysis of possible evolutionary implications." volume="14" year="1967">Albrecht 1967</bibRefCitation>
,
<bibRefCitation id="828B561EEEBA0B7EAC44843F59046B29" DOI="https://doi.org/10.1002/jmor.1051490203" author="Albrecht, PW" journalOrPublisher="Journal of Morphology" pageId="0" pageNumber="13" pagination="159 - 182" refId="B2" refString="Albrecht, PW, 1976. The cranial arteries of turtles and their evolutionary significance. Journal of Morphology 149 (2): 159 - 182, DOI: https://doi.org/10.1002/jmor.1051490203" title="The cranial arteries of turtles and their evolutionary significance." url="https://doi.org/10.1002/jmor.1051490203" volume="149" year="1976">1976</bibRefCitation>
;
<bibRefCitation id="8C4262F04C50F59D4AD1B12A8DF4CD2C" DOI="https://doi.org/10.7717/peerj.10475" author="Rollot, Y" journalOrPublisher="BMC Evolutionary Biology" pageId="0" pageNumber="13" refId="B41" refString="Rollot, Y, Evers, SW, Joyce, WG, 2021a. A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e10475. https://doi.org/10.7717/peerj.10475" title="A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e 10475." url="https://doi.org/10.7717/peerj.10475" year="2021 a">Rollot et al. 2021a</bibRefCitation>
). When viewed from the side, the trigeminal foramen of
<taxonomicName id="02EE9E466352AEBFED27EC4DBC4DDD52" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="069BC47808F9B1CDC82B9E5C3AC429F1" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
is a large, diagonally arranged, oval opening. Superficially, the anterodorsal third of this opening corresponds to the trigeminal passage per se, while the posteroventral third corresponds to the passage of the mandibular artery into the lower temporal fossa. In BSPG 1991 II 130, the descending branch of the prootic is laterally displaced, perhaps obliterating the passage of the lateral head vein and visually separating passage of the trigeminal nerve rami and the mandibular artery. As preserved, only portions of the trigeminal foramen system can be observed, making it necessary to communicate about its subparts. We here explicitly refer to the anterior foramen of BSPG 1991 II 130 as the trigeminal foramen
<emphasis id="19FFD94FDF225DC3057E5666BB74C4EC" italics="true" pageId="0" pageNumber="13">sensu stricto</emphasis>
, but the posterior foramen as the mandibular artery foramen, while recognizing that the two combined, if separated, are homologous with the trigeminal foramen
<emphasis id="D7E6D9F7BE57F33E7BEE2A18DF21CCA0" italics="true" pageId="0" pageNumber="13">sensu lato</emphasis>
of
<taxonomicName id="4A0B24CC9C9883D7F902C2CDF92F045D" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="A5E1E5DDCBA3A08A4BB0A10F4D9BB7A4" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
(see Prootic below).
</paragraph>
<paragraph id="9578C5475E1449A262DF39F939508FE0" pageId="0" pageNumber="13">
<emphasis id="521FF0CCA91351366B1089AD3A79E448" bold="true" pageId="0" pageNumber="13">Nasal.</emphasis>
The nasals are absent in BSPG 1991 II 130 (Fig.
<figureCitation id="863D36E89ECD088369411D959221FC6A" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A-D</figureCitation>
), as in all carettochelyids (
<bibRefCitation id="038525B3DA951F0CFF0B2C78290AC32B" DOI="https://doi.org/10.3853/j.0067-1975.6.1905.994" author="Waite, ER" journalOrPublisher="Records of the Australia Museum" pageId="0" pageNumber="13" pagination="110 - 118" refId="B52" refString="Waite, ER, 1905. The osteology of the New Guinea turtle (Carettochelys insculpta Ramsay). Records of the Australia Museum 6: 110 - 118, DOI: https://doi.org/10.3853/j.0067-1975.6.1905.994" title="The osteology of the New Guinea turtle (Carettochelys insculpta Ramsay)." url="https://doi.org/10.3853/j.0067-1975.6.1905.994" volume="6" year="1905">Waite 1905</bibRefCitation>
;
<bibRefCitation id="7CA3C9FC94E97E045B55CBF18CEC16A2" author="Harrassowitz, H" journalOrPublisher="Abhandlungen der Hessischen Geologischen Landesanstalt" pageId="0" pageNumber="13" pagination="132 - 239" refId="B25" refString="Harrassowitz, H, 1922. Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung. Abhandlungen der Hessischen Geologischen Landesanstalt 6: 132 - 239" title="Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung." volume="6" year="1922">Harrassowitz 1922</bibRefCitation>
;
<bibRefCitation id="FDD5F2A996865917695081A70925F1D1" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="849C826E11F94BA38027B49AF4C55EAB" DOI="https://doi.org/10.1080/02724634.2017.1335735" author="Danilov, IG" journalOrPublisher="Geologische und Palaeontologische Abhandlungen" pageId="0" pageNumber="13" refId="B12" refString="Danilov, IG, Obraztsova, EM, Chen, W, Jianhua, J, 2017. The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37(4): e1335735. https://doi.org/10.1080/02724634.2017.1335735" title="The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37 (4): e 1335735." url="https://doi.org/10.1080/02724634.2017.1335735" year="2017">Danilov et al. 2017</bibRefCitation>
;
<bibRefCitation id="3C5EAAB56E88C9E637946D03DBED445D" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
;
<bibRefCitation id="E460ABBFD775F0A6A7B8667A36B7DD43" DOI="https://doi.org/10.1080/03115518.2023.2243503" author="White, AW" journalOrPublisher="Alcheringa: An Australasian Journal of Palaeontology" pageId="0" pageNumber="13" pagination="1 - 10" refId="B56" refString="White, AW, Archer, M, Hand, SJ, Godthelp, H, Gillespie, AK, 2023. A new broad-snouted fossil carettochelyid turtle from a previously unknown Caenozoic deposit in Sarawak, Malaysia. Alcheringa: An Australasian Journal of Palaeontology 47 (2): 1 - 10, DOI: https://doi.org/10.1080/03115518.2023.2243503" title="A new broad-snouted fossil carettochelyid turtle from a previously unknown Caenozoic deposit in Sarawak, Malaysia." url="https://doi.org/10.1080/03115518.2023.2243503" volume="47" year="2023">White et al. 2023</bibRefCitation>
).
</paragraph>
<paragraph id="69855F73F2FEA96304D17566B40AFEF4" pageId="0" pageNumber="13">
<emphasis id="CC9665567C9D2C1D39BBA5E2BB216645" bold="true" pageId="0" pageNumber="13">Prefrontal.</emphasis>
The two prefrontals are heavily damaged. While most of the right element is missing, with only the most dorsomedial part being apparent, its left counterpart preserves the dorsal plate, but the descending process is completely missing (Fig.
<figureCitation id="04223FA79E6B232CDE5447A8AAA2E83E" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A-D</figureCitation>
). The anterior surface of the left prefrontal is smooth and an articulation facet is missing, showing that the nasal is absent (Fig.
<figureCitation id="A7211299CD9F18D0A9314FA0888CC05A" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1E</figureCitation>
). The prefrontal, therefore, forms the dorsal margin of the apertura narium externa and the dorsal roof of the fossa nasalis. The prefrontal also forms the dorsal margin of the orbit. The ventrolateral portion of the prefrontal forms the dorsal base of the descending process. The lateral half of that base forms an articulation facet, which corresponds to the ventrolateral contact of the prefrontal with the ascending process of the maxilla (Fig.
<figureCitation id="D3FC00219E9B615A463215254A593390" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1C</figureCitation>
), while the medial half ventrally highlights a broken surface, i.e., the area where the descending process of the prefrontal is broken off. The prefrontal otherwise contacts the frontal posteriorly along a convex suture. The left prefrontal additionally exhibits a small, asymmetric, posteromedial contact with the right frontal (Fig.
<figureCitation id="F5944BDD7CFD68274DF1762E991566ED" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A, B</figureCitation>
).
</paragraph>
<paragraph id="BE738BFB749020C6F418DAD3F95797D8" pageId="0" pageNumber="13">
<emphasis id="F0472D30403A6103E50C65F48B4DDB3F" bold="true" pageId="0" pageNumber="13">Frontal.</emphasis>
The two frontals are nearly complete. The right element lacks its most anterolateral portion. Additional, minor damage can be seen along the crista cranii of both bones (Fig.
<figureCitation id="4C427927A42813B8B588DDED2B4D2830" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A, B</figureCitation>
). The frontal contacts the prefrontal anteriorly along a slightly concave suture, the parietal posteriorly, and the postorbital posterolaterally (Fig.
<figureCitation id="57101FEDB0CE878B39167D9E97A2B9C0" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A, B</figureCitation>
). The frontal is wider than long and anterolaterally forms a short process that forms the posterodorsal margin of the orbit (Fig.
<figureCitation id="716FFE4FEC9998100E73EB366480C32C" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A</figureCitation>
). The extent of this contribution to the orbit margin is similar to that of most carettochelyids (
<bibRefCitation id="24A57C288A5612EAB35A0786F3520895" DOI="https://doi.org/10.3853/j.0067-1975.6.1905.994" author="Waite, ER" journalOrPublisher="Records of the Australia Museum" pageId="0" pageNumber="13" pagination="110 - 118" refId="B52" refString="Waite, ER, 1905. The osteology of the New Guinea turtle (Carettochelys insculpta Ramsay). Records of the Australia Museum 6: 110 - 118, DOI: https://doi.org/10.3853/j.0067-1975.6.1905.994" title="The osteology of the New Guinea turtle (Carettochelys insculpta Ramsay)." url="https://doi.org/10.3853/j.0067-1975.6.1905.994" volume="6" year="1905">Waite 1905</bibRefCitation>
;
<bibRefCitation id="685A6710C2A485E17B3D25CA56DC2DD9" author="Harrassowitz, H" journalOrPublisher="Abhandlungen der Hessischen Geologischen Landesanstalt" pageId="0" pageNumber="13" pagination="132 - 239" refId="B25" refString="Harrassowitz, H, 1922. Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung. Abhandlungen der Hessischen Geologischen Landesanstalt 6: 132 - 239" title="Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung." volume="6" year="1922">Harrassowitz 1922</bibRefCitation>
;
<bibRefCitation id="15999EF51F0D960CD6E9813009D8744E" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="B0F14384058C1B8275207286A2052F74" DOI="https://doi.org/10.1080/03115518.2023.2243503" author="White, AW" journalOrPublisher="Alcheringa: An Australasian Journal of Palaeontology" pageId="0" pageNumber="13" pagination="1 - 10" refId="B56" refString="White, AW, Archer, M, Hand, SJ, Godthelp, H, Gillespie, AK, 2023. A new broad-snouted fossil carettochelyid turtle from a previously unknown Caenozoic deposit in Sarawak, Malaysia. Alcheringa: An Australasian Journal of Palaeontology 47 (2): 1 - 10, DOI: https://doi.org/10.1080/03115518.2023.2243503" title="A new broad-snouted fossil carettochelyid turtle from a previously unknown Caenozoic deposit in Sarawak, Malaysia." url="https://doi.org/10.1080/03115518.2023.2243503" volume="47" year="2023">White et al. 2023</bibRefCitation>
) but not
<taxonomicName id="8506D01C27DA4C0E99F4CD07FF6F42CF" baseAuthorityName="Clark" baseAuthorityYear="1932" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira pulchra" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="pulchra">
<emphasis id="340552751B8E803EE695FDDE35E16FD9" italics="true" pageId="0" pageNumber="13">Anosteira pulchra</emphasis>
</taxonomicName>
and
<taxonomicName id="0E886AD4DBF2C270C16A146BDC8B3463" authorityName="Chow &amp; Liu" authorityYear="1955" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira maomingensis" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="maomingensis">
<emphasis id="D3AA8ABB8B60E8AFEC41EEF83F9A9FE8" italics="true" pageId="0" pageNumber="13">Anosteira maomingensis</emphasis>
</taxonomicName>
, in which this contribution is slightly broader (
<bibRefCitation id="21CDF1A2BD7B9CD4E68BD33D4BEAB689" DOI="https://doi.org/10.1080/02724634.2017.1335735" author="Danilov, IG" journalOrPublisher="Geologische und Palaeontologische Abhandlungen" pageId="0" pageNumber="13" refId="B12" refString="Danilov, IG, Obraztsova, EM, Chen, W, Jianhua, J, 2017. The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37(4): e1335735. https://doi.org/10.1080/02724634.2017.1335735" title="The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37 (4): e 1335735." url="https://doi.org/10.1080/02724634.2017.1335735" year="2017">Danilov et al. 2017</bibRefCitation>
;
<bibRefCitation id="526339A85E02E3623A58186DBE8B6DBB" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
). Ventrally, the frontals form low crista cranii, which jointly delimit a moderately broad sulcus olfactorius (Fig.
<figureCitation id="7E71C007C376844203CCAA735FF2646C" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B</figureCitation>
). The posterior half of the two cristae collectively encapsulate an area that is enlarged relative to the sulcus olfactorius and that contained the olfactory bulbs (
<bibRefCitation id="17997C691628172BD5AB6F7F76D984EF" DOI="https://doi.org/10.1093/zoolinnean/zlz063" author="Evers, SW" journalOrPublisher="Zoological Journal of the Linnean Society" pageId="0" pageNumber="13" pagination="800 - 828" refId="B16" refString="Evers, SW, Neenan, JM, Ferreira, GS, Werneburg, I, Barrett, PM, Benson, RB, 2019. Neurovascular anatomy of the protostegid turtle Rhinochelys pulchriceps and comparisons of membranous and endosseous labyrinth shape in an extant turtle. Zoological Journal of the Linnean Society 187 (3): 800 - 828, DOI: https://doi.org/10.1093/zoolinnean/zlz063" title="Neurovascular anatomy of the protostegid turtle Rhinochelys pulchriceps and comparisons of membranous and endosseous labyrinth shape in an extant turtle." url="https://doi.org/10.1093/zoolinnean/zlz063" volume="187" year="2019">Evers et al. 2019</bibRefCitation>
). The anteromedial part of the crista cranii is mediolaterally broadened and forms an oval articulation facet (Fig.
<figureCitation id="3224E5389711DE123EF1F07C5D8214F8" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B</figureCitation>
). This facet, previously not reported by
<bibRefCitation id="5A1DFB8AF1A07A8E6B557175E34DF39C" DOI="https://doi.org/10.3374/014.055.0207" author="Havlik, PE" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="201 - 214" refId="B26" refString="Havlik, PE, Joyce, WG, Boehme, M, 2014. Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya. Bulletin of the Peabody Museum of Natural History 55 (2): 201 - 214, DOI: https://doi.org/10.3374/014.055.0207" title="Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya." url="https://doi.org/10.3374/014.055.0207" volume="55" year="2014">Havlik et al. (2014)</bibRefCitation>
, likely corresponds to a secondary contact between the crista cranii of the frontal and the descending process of the prefrontal. A similar arrangement is present in
<taxonomicName id="847F8BE91CF4F07CA25A533417F15E2C" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys niahensis" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="niahensis">
<emphasis id="E3A02CA5CA59E8EE24D5E5485DE12CBF" italics="true" pageId="0" pageNumber="13">Carettochelys niahensis</emphasis>
</taxonomicName>
, where a secondary contact between the frontal and prefrontal anteriorly delimits a foramen that forms a passage between the orbit and the nasal cavity (
<bibRefCitation id="5E1F171DF755DDB8A6EF2FBFC8E6E7A3" DOI="https://doi.org/10.1080/03115518.2023.2243503" author="White, AW" journalOrPublisher="Alcheringa: An Australasian Journal of Palaeontology" pageId="0" pageNumber="13" pagination="1 - 10" refId="B56" refString="White, AW, Archer, M, Hand, SJ, Godthelp, H, Gillespie, AK, 2023. A new broad-snouted fossil carettochelyid turtle from a previously unknown Caenozoic deposit in Sarawak, Malaysia. Alcheringa: An Australasian Journal of Palaeontology 47 (2): 1 - 10, DOI: https://doi.org/10.1080/03115518.2023.2243503" title="A new broad-snouted fossil carettochelyid turtle from a previously unknown Caenozoic deposit in Sarawak, Malaysia." url="https://doi.org/10.1080/03115518.2023.2243503" volume="47" year="2023">White et al. 2023</bibRefCitation>
). In the extant turtle
<taxonomicName id="5DBFF0A313FB2BE4D350F502B93195BB" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="CF467B4D50E70345ECB0CAF0A6AF532E" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
, such a contact is not present, but the crista cranii closely approaches the descending process of the prefrontal, forming a slit-like passage between the orbital and nasal cavities along the most anterior portion of the foramen interorbitale (
<bibRefCitation id="229FCA38F8C8D7A10A5BDBBA22D7ECAC" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="1A681BA1D72BA47E0C7803B3F6E8DAAA" DOI="https://doi.org/10.3374/014.055.0102" author="Joyce, WG" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="3 - 33" refId="B28" refString="Joyce, WG, 2014. A review of the fossil record of turtles of the clade Pan-Carettochelys. Bulletin of the Peabody Museum of Natural History 55 (1): 3 - 33, DOI: https://doi.org/10.3374/014.055.0102" title="A review of the fossil record of turtles of the clade Pan-Carettochelys." url="https://doi.org/10.3374/014.055.0102" volume="55" year="2014">Joyce 2014</bibRefCitation>
). The condition described for
<taxonomicName id="27FAB3FE80EAD9D8D102235EFC28CF08" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys niahensis" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="niahensis">
<emphasis id="59F9FD05F63A9C2EB319E24DC63A1415" italics="true" pageId="0" pageNumber="13">Carettochelys niahensis</emphasis>
</taxonomicName>
and
<taxonomicName id="B126F8AA1704EAE8FCF311E24A094FD4" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="614FB78E20F7B1E1BE7931DCBB7040E4" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
likely highlights an extended degree of ossification of the interorbital area compared to
<taxonomicName id="1645D06B7ADF6157912462B36B2DF6DC" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="BEEACE6633B2E88F43C51944EDE08D0D" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
.
</paragraph>
<paragraph id="CE52401E21FF7E35BB54553C572016A5" pageId="0" pageNumber="13">
<emphasis id="0620B9C8A848697BF447E09B134E3548" bold="true" pageId="0" pageNumber="13">Parietal.</emphasis>
The parietal forms the posterior half of the skull roof, the lateral half of the upper temporal emargination, and roofs the braincase. The dorsal plate of the parietal is nearly complete, only missing its most distal part, and contacts the frontal anteriorly, the postorbital anterolaterally, and the supraoccipital posteroventrally (Fig.
<figureCitation id="4A02BD4F3725DF6B623CB959511C34FE" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1</figureCitation>
). Within the upper temporal fossa, the parietal contacts the prootic laterally and the supraoccipital posteriorly (Fig.
<figureCitation id="47DBEFC8E4A4571E6B905A0A3A487F81" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A</figureCitation>
). The descending process of each parietal is severely damaged and only preserves its most dorsal portions (Fig.
<figureCitation id="9E6128011EEF144519878C01CB2663E3" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1C, D</figureCitation>
). Nevertheless, the bony contacts of the parietal around the foramen nervi trigemini
<emphasis id="1DAAE12D7254F03048FB257CC89FF021" italics="true" pageId="0" pageNumber="13">sensu stricto</emphasis>
can be inferred based on comparisons with the extant
<taxonomicName id="38DC0A403ED36F30538656B297C459A3" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="42A3414373555F13FD60D27037B4BCE1" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
. In both the extant form and BSPG 1991 II 130, the posterior margin of the foramen nervi trigemini
<emphasis id="A46BFDB202E7B62A5DD8B71EC18C3F1F" italics="true" pageId="0" pageNumber="13">sensu stricto</emphasis>
is imprinted onto the anterior surface of the prootic. The dorsal end of this imprint is formed by a small, anteroventral bump-like process of the prootic, which is well visible in the fossil on both sides. As preserved, this bump prohibits the posterior end of the descending process of the parietal to enter the dorsal margin of the foramen nervi trigemini
<emphasis id="5AF33DFC5056F9D6D10609D289744236" italics="true" pageId="0" pageNumber="13">sensu stricto</emphasis>
on the right side of the fossil. This can also be appreciated on the left side, where the process is broken, but where the prootic bump and sutural contact for the descending process indicate a symmetrical morphology with the right side. In
<taxonomicName id="5D77E157F117F2EDE0FABD18F69CF1D6" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="96053F9380EA38BEADEB68C7D4846EB6" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
, the prootic bump serves as an articulation site for a posterodorsal process of the epipterygoid, which prohibits the descending parietal process from entering the trigeminal foramen
<emphasis id="C1BB3BCD80B4C0D5EA0FADDA5CFBA492" italics="true" pageId="0" pageNumber="13">sensu stricto</emphasis>
margin at a more anterior position. The morphology of BSPG 1991 II 130 is fully consistent with that of
<taxonomicName id="97677D3CAF0439998F76FB37E4D52765" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="F486221679D346153253A9638584327D" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
, and thus it is reasonable to infer that an epipterygoid-prootic contact in the anterodorsal margin of the foramen nervi trigemini
<emphasis id="CFE2DD8547E463E23C9D93BF34F70A3A" italics="true" pageId="0" pageNumber="13">sensu stricto</emphasis>
precluded a parietal contribution to this opening. The preserved portion of the descending process shows that it is continuous with the crista cranii of the frontal and also forms a prominent ridge along its lateral surface that extends posteroventrolaterally from the base of the process within the upper temporal fossa (Fig.
<figureCitation id="BBB90DC86574419A09A3F8C9916106C6" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B, E</figureCitation>
). This ridge is continuous with the processus trochlearis oticum, and forms parts of its anteriorly overhanging margin, as in
<taxonomicName id="183B307575323094D41F945A5680127C" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="962E3B496A135D6FC1F6A51577C23E98" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
and
<taxonomicName id="678853F11A04EE1DEE1C260AD1C50400" authorityName="Chow &amp; Liu" authorityYear="1955" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira maomingensis" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="maomingensis">
<emphasis id="CB6E263FEE9E64865FAA2EC7DBD27908" italics="true" pageId="0" pageNumber="13">Anosteira maomingensis</emphasis>
</taxonomicName>
(
<bibRefCitation id="0ED5B471F1F23C680D7F00D56975C16F" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="5213B90756B7A6EDB6E8B18A6ECFAD1F" DOI="https://doi.org/10.3374/014.055.0102" author="Joyce, WG" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="3 - 33" refId="B28" refString="Joyce, WG, 2014. A review of the fossil record of turtles of the clade Pan-Carettochelys. Bulletin of the Peabody Museum of Natural History 55 (1): 3 - 33, DOI: https://doi.org/10.3374/014.055.0102" title="A review of the fossil record of turtles of the clade Pan-Carettochelys." url="https://doi.org/10.3374/014.055.0102" volume="55" year="2014">Joyce 2014</bibRefCitation>
;
<bibRefCitation id="57C1D4714890291FC730F4E8A048AE7A" DOI="https://doi.org/10.1080/02724634.2017.1335735" author="Danilov, IG" journalOrPublisher="Geologische und Palaeontologische Abhandlungen" pageId="0" pageNumber="13" refId="B12" refString="Danilov, IG, Obraztsova, EM, Chen, W, Jianhua, J, 2017. The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37(4): e1335735. https://doi.org/10.1080/02724634.2017.1335735" title="The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37 (4): e 1335735." url="https://doi.org/10.1080/02724634.2017.1335735" year="2017">Danilov et al. 2017</bibRefCitation>
). Within the braincase, the descending process of the parietal is deeply recessed and, jointly with the prootic, forms a broad cavity that housed large cerebral hemispheres, as in trionychians more generally (Fig.
<figureCitation id="14C51BF9E349DE48F8994CD54C8EEC0D" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B</figureCitation>
;
<bibRefCitation id="9B4142D2966E4035866DD745ED8E9595" DOI="https://doi.org/10.1007/978-3-031-13983-3_4" author="Ferreira, GS" editor="Dozo, MT" journalOrPublisher="Springer International Publishing, Cham" pageId="0" pageNumber="13" pagination="79 - 121" refId="B19" refString="Ferreira, GS, Werneburg, I, Lautenschlager, S, Evers, SW, 2023. Contrasting brains and bones: neuroanatomical evolution of turtles (Testudinata). In: Dozo, MT, Paulina-Carabajal, A, Macrini, TE, Walsh, S, Eds., Paleoneurology of amniotes: new directions in the study of fossil endocasts. Springer International Publishing, Cham: 79 - 121, DOI: https://doi.org/10.1007/978-3-031-13983-3_4" title="Contrasting brains and bones: neuroanatomical evolution of turtles (Testudinata)." url="https://doi.org/10.1007/978-3-031-13983-3_4" volumeTitle="Paleoneurology of amniotes: new directions in the study of fossil endocasts." year="2023">Ferreira et al. 2023</bibRefCitation>
). In the median contact of both parietals, there is an additional constriction of the brain cavity toward the supraoccipital contact, which corresponds to a median, bulge-like cartilaginous rider (
<bibRefCitation id="588CBA5B76DC6E0F070E755831B5A1A8" DOI="https://doi.org/10.3897/vz.71.e66756" author="Werneburg, I" journalOrPublisher="Vertebrate Zoology" pageId="0" pageNumber="13" pagination="403 - 418" refId="B54" refString="Werneburg, I, Evers, SW, Ferreira, G, 2021. On the &quot;cartilaginous rider&quot; in the endocasts of turtle brain cavities. Vertebrate Zoology 71: 403 - 418, DOI: https://doi.org/10.3897/vz.71.e66756" title="On the &quot; cartilaginous rider &quot; in the endocasts of turtle brain cavities." url="https://doi.org/10.3897/vz.71.e66756" volume="71" year="2021">Werneburg et al. 2021</bibRefCitation>
).
</paragraph>
<paragraph id="5D6A578920CBAE372D72DEEB8C14D3C7" pageId="0" pageNumber="13">
<emphasis id="657A5B587C1FADA935404410A84809DA" bold="true" pageId="0" pageNumber="13">Postorbital.</emphasis>
The postorbitals are almost completely missing. Only the most medial portion of the left element is preserved, which contacts the frontal anteromedially and the parietal posteromedially (Fig.
<figureCitation id="3130DD575D15227E3EDC13220B61E755" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A, B</figureCitation>
). The fully preserved left frontal and parietal and comparisons with
<taxonomicName id="450C4D2AF400F2021859EA1261C9A89E" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="2BCBA0AC6BA1C2826B17D77F5F32B3A5" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
also allow to infer that the postorbital contributed to the orbital margin and the upper temporal emargination.
</paragraph>
<paragraph id="A089B8775A666F5B516DFAD222576C2F" pageId="0" pageNumber="13">
<emphasis id="65B1AB84C352487907101D77193F10EC" bold="true" pageId="0" pageNumber="13">Jugal.</emphasis>
The jugals are not preserved in BSPG 1991 II 130.
</paragraph>
<paragraph id="7A782FE308718D49AC78E2EEE43BBC5C" pageId="0" pageNumber="13">
<emphasis id="219CE0C6C5134C5AFDC5DD576ACC05B7" bold="true" pageId="0" pageNumber="13">Quadratojugal.</emphasis>
A small part of the right quadratojugal was described by
<bibRefCitation id="AC2A3C8CDC53C8F6D13C7925F340B12D" DOI="https://doi.org/10.3374/014.055.0207" author="Havlik, PE" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="201 - 214" refId="B26" refString="Havlik, PE, Joyce, WG, Boehme, M, 2014. Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya. Bulletin of the Peabody Museum of Natural History 55 (2): 201 - 214, DOI: https://doi.org/10.3374/014.055.0207" title="Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya." url="https://doi.org/10.3374/014.055.0207" volume="55" year="2014">Havlik et al. (2014)</bibRefCitation>
as preserved in articulation with the remainder of the fossil, in a position anteroventral to the cavum tympani. This portion of the quadratojugal disarticulated along its suture with the quadrate in the specimen prior to CT scanning but was scanned alongside the rest of the fossil. The ventral margin of the quadratojugal fragment was formerly aligned with the ventral margin of the
<normalizedToken id="68791326701BD502E624D728FB708E78" originalValue="quadrate’s">quadrate's</normalizedToken>
articular process and showed no indication of a dorsal upcurving that is generally present in taxa with moderate or deep cheek emarginations. Instead, the fragment is fully consistent with the morphology of
<taxonomicName id="28F81096585E02CACB597C080C960796" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="86A23E0C9E3597AD0225CE8D5E2E00EC" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
, in which the cheek emargination is minimal and limited to a more anterior portion of the quadratojugal (
<bibRefCitation id="9B6B7E50D340CD31D5A9ED9BBC1C9F34" DOI="https://doi.org/10.3853/j.0067-1975.6.1905.994" author="Waite, ER" journalOrPublisher="Records of the Australia Museum" pageId="0" pageNumber="13" pagination="110 - 118" refId="B52" refString="Waite, ER, 1905. The osteology of the New Guinea turtle (Carettochelys insculpta Ramsay). Records of the Australia Museum 6: 110 - 118, DOI: https://doi.org/10.3853/j.0067-1975.6.1905.994" title="The osteology of the New Guinea turtle (Carettochelys insculpta Ramsay)." url="https://doi.org/10.3853/j.0067-1975.6.1905.994" volume="6" year="1905">Waite 1905</bibRefCitation>
;
<bibRefCitation id="373ADA873761A2202CF4AEEF75670019" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="E66B5CE39000C2C3550C287C41411C94" DOI="https://doi.org/10.3374/014.055.0102" author="Joyce, WG" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="3 - 33" refId="B28" refString="Joyce, WG, 2014. A review of the fossil record of turtles of the clade Pan-Carettochelys. Bulletin of the Peabody Museum of Natural History 55 (1): 3 - 33, DOI: https://doi.org/10.3374/014.055.0102" title="A review of the fossil record of turtles of the clade Pan-Carettochelys." url="https://doi.org/10.3374/014.055.0102" volume="55" year="2014">Joyce 2014</bibRefCitation>
). In addition, the preserved quadrates on both sides of BSPG 1991 II 130 show that the posterodorsal articulation of the quadratojugal with the quadrate was limited to the anterodorsal margin of the cavum tympani and did not extend posteriorly further along the dorsal margin. A quadratojugal-squamosal contact was certainly absent in BSPG 1991 II 130 as the articular facets of the quadratojugal and squamosal on the quadrates are widely spaced from one another, much as in
<taxonomicName id="A8DDE1D6F1FE508004561730AB4E33B9" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="2C766F12957D7C321E09A17DCF1D660C" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
.
</paragraph>
<paragraph id="900120322BFE6958C11A643A75B4BBFC" pageId="0" pageNumber="13">
<emphasis id="530E1CF51DC3F26CF3ADEAA4FEC163DC" bold="true" pageId="0" pageNumber="13">Squamosal.</emphasis>
The squamosals are not preserved in BSPG 1991 II 130. Nevertheless, the quadrates on both sides show well-developed articular facets for the squamosals. These facets are triangular and somewhat broader than in
<taxonomicName id="E8257E6E8AB207D9F6DC148772CE17B9" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="02CEAA4173CDF3B78F0AAFE382F37AE3" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
. However, as in the extant taxon, the facets are anteriorly clearly separated from those of the quadratojugal, showing that no contact with the quadratojugal was present. The quadrate bone surrounding the squamosal facet furthermore shows that, again as in
<taxonomicName id="85DF271AF5F59B11C5E46115732492CF" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="9FBF9F39DC32C1A5848D60FA86FE8314" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
, the squamosal of BSPG 1991 II 130 was excluded from the posterodorsal margin of the cavum tympani.
</paragraph>
<paragraph id="CF32230072C9AD104EA0F8640182F1F4" pageId="0" pageNumber="13">
<emphasis id="B1C85BFD42FE0458C0FCE79BCC465001" bold="true" pageId="0" pageNumber="13">Premaxilla.</emphasis>
The premaxillae are not preserved in BSPG 1991 II 130.
</paragraph>
<paragraph id="1FE3B78476D51D6F6C89362D8F0F38C0" pageId="0" pageNumber="13">
<emphasis id="DE49DD63A05A33AE6147673381B9E1F7" bold="true" pageId="0" pageNumber="13">Maxilla.</emphasis>
The maxillae are not preserved in BSPG 1991 II 130.
</paragraph>
<paragraph id="FC552142D9CEEF4146B2E313F29834B6" pageId="0" pageNumber="13">
<emphasis id="8EAE0BECEAFC463B74E03D54EBE30329" bold="true" pageId="0" pageNumber="13">Palatine.</emphasis>
The
<normalizedToken id="A26E84E285CA43B7CF2DF7CE13B8DB84" originalValue="µCT">µCT</normalizedToken>
scans of BSPG 1991 II 130 reveal that a very small portion of the right palatine is preserved just anterior to the suture between the parabasisphenoid and pterygoid (Fig.
<figureCitation id="6ECFAC424F3B772C4A809AAFB6192593" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B, E</figureCitation>
). Although this piece is so small that it barely allows making statements about the anatomy of the palatine, it nevertheless shows that a contact between the palatine and pterygoid, and palatine and parabasisphenoid was present, as in all carettochelyids (
<bibRefCitation id="38202661F7BAC65382A63DA7FA095034" DOI="https://doi.org/10.3853/j.0067-1975.6.1905.994" author="Waite, ER" journalOrPublisher="Records of the Australia Museum" pageId="0" pageNumber="13" pagination="110 - 118" refId="B52" refString="Waite, ER, 1905. The osteology of the New Guinea turtle (Carettochelys insculpta Ramsay). Records of the Australia Museum 6: 110 - 118, DOI: https://doi.org/10.3853/j.0067-1975.6.1905.994" title="The osteology of the New Guinea turtle (Carettochelys insculpta Ramsay)." url="https://doi.org/10.3853/j.0067-1975.6.1905.994" volume="6" year="1905">Waite 1905</bibRefCitation>
;
<bibRefCitation id="518F70E3C5E6E1DC07710D0E2973232B" author="Harrassowitz, H" journalOrPublisher="Abhandlungen der Hessischen Geologischen Landesanstalt" pageId="0" pageNumber="13" pagination="132 - 239" refId="B25" refString="Harrassowitz, H, 1922. Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung. Abhandlungen der Hessischen Geologischen Landesanstalt 6: 132 - 239" title="Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung." volume="6" year="1922">Harrassowitz 1922</bibRefCitation>
;
<bibRefCitation id="F10B9142A1FA34D8810C1D4701804C9A" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="AC45F1CBC209FBCEAA8BE2316E679495" DOI="https://doi.org/10.1080/02724634.2017.1335735" author="Danilov, IG" journalOrPublisher="Geologische und Palaeontologische Abhandlungen" pageId="0" pageNumber="13" refId="B12" refString="Danilov, IG, Obraztsova, EM, Chen, W, Jianhua, J, 2017. The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37(4): e1335735. https://doi.org/10.1080/02724634.2017.1335735" title="The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37 (4): e 1335735." url="https://doi.org/10.1080/02724634.2017.1335735" year="2017">Danilov et al. 2017</bibRefCitation>
;
<bibRefCitation id="588D9CB02E1EA11F489DB4F1D41351AC" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
). The location of this fragment at the level of the sella turcica between the pterygoid and parabasisphenoid also suggests that a contact of the pterygoid with its counterpart was likely absent, again, as in all carettochelyids (
<bibRefCitation id="B1BF4117CE34C2917831C629C39D1410" DOI="https://doi.org/10.3853/j.0067-1975.6.1905.994" author="Waite, ER" journalOrPublisher="Records of the Australia Museum" pageId="0" pageNumber="13" pagination="110 - 118" refId="B52" refString="Waite, ER, 1905. The osteology of the New Guinea turtle (Carettochelys insculpta Ramsay). Records of the Australia Museum 6: 110 - 118, DOI: https://doi.org/10.3853/j.0067-1975.6.1905.994" title="The osteology of the New Guinea turtle (Carettochelys insculpta Ramsay)." url="https://doi.org/10.3853/j.0067-1975.6.1905.994" volume="6" year="1905">Waite 1905</bibRefCitation>
;
<bibRefCitation id="7E8EE839572B44C8ED626A4171E64CAA" author="Harrassowitz, H" journalOrPublisher="Abhandlungen der Hessischen Geologischen Landesanstalt" pageId="0" pageNumber="13" pagination="132 - 239" refId="B25" refString="Harrassowitz, H, 1922. Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung. Abhandlungen der Hessischen Geologischen Landesanstalt 6: 132 - 239" title="Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung." volume="6" year="1922">Harrassowitz 1922</bibRefCitation>
;
<bibRefCitation id="AEA929F53BFA0478A560EAC3D7AB549F" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="3D78816C60BD0890802CAD0C3FDF8117" DOI="https://doi.org/10.1080/02724634.2017.1335735" author="Danilov, IG" journalOrPublisher="Geologische und Palaeontologische Abhandlungen" pageId="0" pageNumber="13" refId="B12" refString="Danilov, IG, Obraztsova, EM, Chen, W, Jianhua, J, 2017. The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37(4): e1335735. https://doi.org/10.1080/02724634.2017.1335735" title="The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37 (4): e 1335735." url="https://doi.org/10.1080/02724634.2017.1335735" year="2017">Danilov et al. 2017</bibRefCitation>
;
<bibRefCitation id="7A7F1B7EAD6A93C131498BC32D21DE51" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
).
</paragraph>
<paragraph id="B6981A46C63D170BF8C7B5CAEB97C43D" pageId="0" pageNumber="13">
<emphasis id="3B9AD1F0203ED234A05042BDD897B643" bold="true" pageId="0" pageNumber="13">Vomer.</emphasis>
The vomer is not preserved in BSPG 1991 II 130.
</paragraph>
<paragraph id="E21CF4776055E2614A09F21165C8E6E6" pageId="0" pageNumber="13">
<emphasis id="8F65FB3B73DC9A2CB978377A21C04757" bold="true" pageId="0" pageNumber="13">Pterygoid.</emphasis>
Only the posterior half of the pterygoids are preserved in BSPG 1991 II 130, which contact the parabasisphenoid medially, the palatine anteriorly, the prootic anterodorsolaterally, the quadrate laterally, the basioccipital posteromedially, the opisthotic posterodorsally, and the exoccipital posterodorsomedially (Figs
<figureCitation id="63BE5E7119AF41F0E0CACC289C41424D" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B, E</figureCitation>
,
<figureCitation id="67B653DBA310CA21A72279F5D0872096" captionStart="Figure 2" captionStartId="F2" captionText="Figure 2. Three-dimensional renderings of the circulatory system of BSPG 1991 II 113. A. Dorsal view; B. Dorsal view with bones rendered transparent. Abbreviations: af-op, articulation facet for the opisthotic; ccb, canalis caroticus basisphenoidalis; cci, canalis caroticus internus; cnf, canalis nervus facialis; cprnv, canalis pro ramo nervi vidiani; faccb, foramen anterius canalis carotici basisphenoidalis; fpcci, foramen posterius canalis carotici interni; fpcna, foramen posterius canalis nervi abducentis; pbs, parabasisphenoid; pt, pterygoid; stag, stapedial artery groove." figureDoi="10.3897/fr.27.115046.figure2" httpUri="https://binary.pensoft.net/fig/961958" pageId="0" pageNumber="13">2</figureCitation>
). Additionally, there was likely a contact with the epipterygoid. Ventrally, the pterygoid forms a deep pterygoid fossa and contributes to the elongate tubercula basioccipitale anterolaterally (Fig.
<figureCitation id="150BDF558BF78CF00EC2BAACDC689D40" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B</figureCitation>
). At about mid-length between the parabasisphenoid and quadrate, the pterygoid forms a low ridge that delineates the pterygoid fossa medially (Fig.
<figureCitation id="2E48F9122A92F7991C4512EA2F245E53" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B</figureCitation>
). The ridge is ventrally broken, and it likely formed an enfolded structure that partially covered the pterygoid fossa ventrally, as in
<taxonomicName id="FF5CED64554A0E985EF797FB0A3ED2F6" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="F6506EAE1E1DD7002243C54E072CDE75" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
(
<bibRefCitation id="47D3923B869825E6B2F31AE2FCAF007C" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="786BEB5EE0F1F558122C37536F8C53D8" DOI="https://doi.org/10.3374/014.055.0102" author="Joyce, WG" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="3 - 33" refId="B28" refString="Joyce, WG, 2014. A review of the fossil record of turtles of the clade Pan-Carettochelys. Bulletin of the Peabody Museum of Natural History 55 (1): 3 - 33, DOI: https://doi.org/10.3374/014.055.0102" title="A review of the fossil record of turtles of the clade Pan-Carettochelys." url="https://doi.org/10.3374/014.055.0102" volume="55" year="2014">Joyce 2014</bibRefCitation>
), but likely not
<taxonomicName id="3D2061D351D8FAAE2D1768B1788FE288" authorityName="Chow &amp; Liu" authorityYear="1955" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira maomingensis" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="maomingensis">
<emphasis id="23CDE6D40347A078DA09A025A83EB026" italics="true" pageId="0" pageNumber="13">Anosteira maomingensis</emphasis>
</taxonomicName>
, in which this ridge seems to be absent (
<bibRefCitation id="81856E4AF4308A20CC217795C57F940A" DOI="https://doi.org/10.1080/02724634.2017.1335735" author="Danilov, IG" journalOrPublisher="Geologische und Palaeontologische Abhandlungen" pageId="0" pageNumber="13" refId="B12" refString="Danilov, IG, Obraztsova, EM, Chen, W, Jianhua, J, 2017. The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37(4): e1335735. https://doi.org/10.1080/02724634.2017.1335735" title="The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37 (4): e 1335735." url="https://doi.org/10.1080/02724634.2017.1335735" year="2017">Danilov et al. 2017</bibRefCitation>
), and definitely not
<taxonomicName id="0FF823B8E114A3191E715115FDCE0E4F" baseAuthorityName="Clark" baseAuthorityYear="1932" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira pulchra" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="pulchra">
<emphasis id="604EC549999A3B02B18BDDB78B320A9C" italics="true" pageId="0" pageNumber="13">Anosteira pulchra</emphasis>
</taxonomicName>
, in which the ridge is clearly absent (
<bibRefCitation id="9B6CA326DD2A08015941E249EF3387EE" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
). The pterygoid of BSPG 1991 II 130 ventromedially minorly enters the margin of the mandibular artery foramen (Figs
<figureCitation id="E55825B30E50D7ABE6111925AC611459" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1E</figureCitation>
,
<figureCitation id="865653068E6EB1475BC50A66F2F21AE7" captionStart="Figure 3" captionStartId="F3" captionText="Figure 3. Three-dimensional renderings of the left trigeminal area of Allaeochelys libyca (BSPG 1991 II 113) and Carettochelys insculpta (NHMUK 1903.7.10.1). A. Left trigeminal area of Allaeochelys libyca in anterolateral view; B. Close-up on the left trigeminal area of Allaeochelys libyca; C. Left trigeminal area of Carettochelys insculpta in anterolateral view; D. Close-up on the left trigeminal area of Carettochelys insculpta; E. Left trigeminal area of Carettochelys insculpta in anterolateral view with the epipterygoid removed; F. Close-up on the left trigeminal area of Carettochelys insculpta with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in Carettochelys insculpta." figureDoi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13">3</figureCitation>
). The ventral half of the canalis pro ramo nervi vidiani, which transmits the vidian nerve from the geniculate ganglion to the canalis caroticus internus (
<bibRefCitation id="68A41B290B87910C74B8D44045343931" author="Gaffney, ES" journalOrPublisher="Bulletin of the American Museum of Natural History" pageId="0" pageNumber="13" pagination="65 - 376" refId="B22" refString="Gaffney, ES, 1979. Comparative cranial morphology of recent and fossil turtles. Bulletin of the American Museum of Natural History 164: 65 - 376" title="Comparative cranial morphology of recent and fossil turtles." volume="164" year="1979">Gaffney 1979</bibRefCitation>
;
<bibRefCitation id="DA681CCF021FDB8BC26C66D88FB09AE4" DOI="https://doi.org/10.7717/peerj.10475" author="Rollot, Y" journalOrPublisher="BMC Evolutionary Biology" pageId="0" pageNumber="13" refId="B41" refString="Rollot, Y, Evers, SW, Joyce, WG, 2021a. A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e10475. https://doi.org/10.7717/peerj.10475" title="A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e 10475." url="https://doi.org/10.7717/peerj.10475" year="2021 a">Rollot et al. 2021a</bibRefCitation>
), is also formed by the pterygoid (Fig.
<figureCitation id="9D2D6AC415B2037318D25B76015FBECF" captionStart="Figure 2" captionStartId="F2" captionText="Figure 2. Three-dimensional renderings of the circulatory system of BSPG 1991 II 113. A. Dorsal view; B. Dorsal view with bones rendered transparent. Abbreviations: af-op, articulation facet for the opisthotic; ccb, canalis caroticus basisphenoidalis; cci, canalis caroticus internus; cnf, canalis nervus facialis; cprnv, canalis pro ramo nervi vidiani; faccb, foramen anterius canalis carotici basisphenoidalis; fpcci, foramen posterius canalis carotici interni; fpcna, foramen posterius canalis nervi abducentis; pbs, parabasisphenoid; pt, pterygoid; stag, stapedial artery groove." figureDoi="10.3897/fr.27.115046.figure2" httpUri="https://binary.pensoft.net/fig/961958" pageId="0" pageNumber="13">2A</figureCitation>
). The pterygoid floors the endosseous labyrinth and cavum acustico-jugulare and forms the ventral margin of the fenestra ovalis and ventromedial margin of the small fenestra postotica. Dorsally, at about mid-length, the pterygoid forms a low bulging articulation facet for contact with the processus interfenestralis of the opisthotic (Fig.
<figureCitation id="6375D0059BA6FE6AE4BB04145FA6A1A7" captionStart="Figure 2" captionStartId="F2" captionText="Figure 2. Three-dimensional renderings of the circulatory system of BSPG 1991 II 113. A. Dorsal view; B. Dorsal view with bones rendered transparent. Abbreviations: af-op, articulation facet for the opisthotic; ccb, canalis caroticus basisphenoidalis; cci, canalis caroticus internus; cnf, canalis nervus facialis; cprnv, canalis pro ramo nervi vidiani; faccb, foramen anterius canalis carotici basisphenoidalis; fpcci, foramen posterius canalis carotici interni; fpcna, foramen posterius canalis nervi abducentis; pbs, parabasisphenoid; pt, pterygoid; stag, stapedial artery groove." figureDoi="10.3897/fr.27.115046.figure2" httpUri="https://binary.pensoft.net/fig/961958" pageId="0" pageNumber="13">2A</figureCitation>
). This dorsal articular boss is unusual among turtles, but certainly present in
<taxonomicName id="D9FCB2E3FE300D84E3570B2ACBDC6267" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="CF2CDB289E5F5409AA69AB6FA2CD6243" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
. Within the cavum acustico-jugulare, the posterodorsal surface of the pterygoid forms a narrow groove, as in
<taxonomicName id="7AEE04589145397C0FC1751A802DB22E" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="62178CA8C734E7286FB7475DC42880D9" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
, and that is interpreted as having housed the stapedial artery and/or the lateral head vein (Fig.
<figureCitation id="DAF244DA155950D378BC548EC0056665" captionStart="Figure 2" captionStartId="F2" captionText="Figure 2. Three-dimensional renderings of the circulatory system of BSPG 1991 II 113. A. Dorsal view; B. Dorsal view with bones rendered transparent. Abbreviations: af-op, articulation facet for the opisthotic; ccb, canalis caroticus basisphenoidalis; cci, canalis caroticus internus; cnf, canalis nervus facialis; cprnv, canalis pro ramo nervi vidiani; faccb, foramen anterius canalis carotici basisphenoidalis; fpcci, foramen posterius canalis carotici interni; fpcna, foramen posterius canalis nervi abducentis; pbs, parabasisphenoid; pt, pterygoid; stag, stapedial artery groove." figureDoi="10.3897/fr.27.115046.figure2" httpUri="https://binary.pensoft.net/fig/961958" pageId="0" pageNumber="13">2A</figureCitation>
). Posteriorly, the pterygoid entirely forms the foramen posterius canalis carotici interni, the position of which differs from the early branching carettochelyids
<taxonomicName id="E6EDE6E4C5CBADEBE5AB4C2B19EF6A48" baseAuthorityName="Clark" baseAuthorityYear="1932" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira pulchra" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="pulchra">
<emphasis id="DE5222917089C15D57428C4F9092D602" italics="true" pageId="0" pageNumber="13">Anosteira pulchra</emphasis>
</taxonomicName>
(
<bibRefCitation id="CACEFA7C627FED0EBCAF1AF673A5C210" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
) and
<taxonomicName id="FA41AD50D258677837E87C1906E5724F" authorityName="Chow &amp; Liu" authorityYear="1955" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira maomingensis" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="maomingensis">
<emphasis id="F77D330D2BF31A2CD0DC3551E0185725" italics="true" pageId="0" pageNumber="13">Anosteira maomingensis</emphasis>
</taxonomicName>
(
<bibRefCitation id="75A010422B960D6E0CF84222DAE4C657" DOI="https://doi.org/10.1080/02724634.2017.1335735" author="Danilov, IG" journalOrPublisher="Geologische und Palaeontologische Abhandlungen" pageId="0" pageNumber="13" refId="B12" refString="Danilov, IG, Obraztsova, EM, Chen, W, Jianhua, J, 2017. The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37(4): e1335735. https://doi.org/10.1080/02724634.2017.1335735" title="The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37 (4): e 1335735." url="https://doi.org/10.1080/02724634.2017.1335735" year="2017">Danilov et al. 2017</bibRefCitation>
), in which the foramen is located more anteroventrally and between the parabasisphenoid and pterygoid, similar to the generalized position of paracryptodires (
<bibRefCitation id="0E33899C964E3CA97CAF2F5751D11CA1" author="Gaffney, ES" journalOrPublisher="Bulletin of the American Museum of Natural History" pageId="0" pageNumber="13" pagination="387 - 436" refId="B21" refString="Gaffney, ES, 1975. A phylogeny and classification of the higher categories of turtles. Bulletin of the American Museum of Natural History 155: 387 - 436" title="A phylogeny and classification of the higher categories of turtles." volume="155" year="1975">Gaffney 1975</bibRefCitation>
). The foramen posterius canalis carotici interni of BSPG 1991 II 130 leads into the canalis caroticus internus, which extends anteromedially through the pterygoid (Fig.
<figureCitation id="09CAF3F335ACEC69BF9528DB024FB2BF" captionStart="Figure 2" captionStartId="F2" captionText="Figure 2. Three-dimensional renderings of the circulatory system of BSPG 1991 II 113. A. Dorsal view; B. Dorsal view with bones rendered transparent. Abbreviations: af-op, articulation facet for the opisthotic; ccb, canalis caroticus basisphenoidalis; cci, canalis caroticus internus; cnf, canalis nervus facialis; cprnv, canalis pro ramo nervi vidiani; faccb, foramen anterius canalis carotici basisphenoidalis; fpcci, foramen posterius canalis carotici interni; fpcna, foramen posterius canalis nervi abducentis; pbs, parabasisphenoid; pt, pterygoid; stag, stapedial artery groove." figureDoi="10.3897/fr.27.115046.figure2" httpUri="https://binary.pensoft.net/fig/961958" pageId="0" pageNumber="13">2B</figureCitation>
) before entering the parabasisphenoid as the canalis caroticus basisphenoidalis. A canalis caroticus lateralis is absent, as in
<taxonomicName id="140A8FDF41D5110826C541B5E2B9CBF7" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="F406DE652E9BD68CE813BB47B3B52A2B" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
(
<bibRefCitation id="8734E5D41711552A444CFA75CDF7810B" DOI="https://doi.org/10.7717/peerj.10475" author="Rollot, Y" journalOrPublisher="BMC Evolutionary Biology" pageId="0" pageNumber="13" refId="B41" refString="Rollot, Y, Evers, SW, Joyce, WG, 2021a. A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e10475. https://doi.org/10.7717/peerj.10475" title="A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e 10475." url="https://doi.org/10.7717/peerj.10475" year="2021 a">Rollot et al. 2021a</bibRefCitation>
). At about mid-length, the canalis caroticus internus is slightly exposed dorsally within the floor of the endosseous labyrinth (Fig.
<figureCitation id="673B6C6923CA0682CFEBA09040EDB938" captionStart="Figure 2" captionStartId="F2" captionText="Figure 2. Three-dimensional renderings of the circulatory system of BSPG 1991 II 113. A. Dorsal view; B. Dorsal view with bones rendered transparent. Abbreviations: af-op, articulation facet for the opisthotic; ccb, canalis caroticus basisphenoidalis; cci, canalis caroticus internus; cnf, canalis nervus facialis; cprnv, canalis pro ramo nervi vidiani; faccb, foramen anterius canalis carotici basisphenoidalis; fpcci, foramen posterius canalis carotici interni; fpcna, foramen posterius canalis nervi abducentis; pbs, parabasisphenoid; pt, pterygoid; stag, stapedial artery groove." figureDoi="10.3897/fr.27.115046.figure2" httpUri="https://binary.pensoft.net/fig/961958" pageId="0" pageNumber="13">2</figureCitation>
). Dorsal to the foramen posterius canalis carotici interni, the pterygoid forms a bony platform that contacts the opisthotic dorsally, forming a secondary wall posterior to the processus interfenestralis, as in
<taxonomicName id="FB81FFDB68A941575FB0616E23D6EB34" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="BCE5D8F92659C4872CF4686F71A18782" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
(
<bibRefCitation id="55319ABA05C85A842EB499CB82F94B85" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
).
</paragraph>
<caption id="9868742F989779AAA2156E49E124B496" doi="10.3897/fr.27.115046.figure2" httpUri="https://binary.pensoft.net/fig/961958" pageId="0" pageNumber="13" start="Figure 2" startId="F2">
<paragraph id="CFEA8910AA6638E84CE51F5DFBAFB455" pageId="0" pageNumber="13">
<emphasis id="ED1BCF2F2A007CB32A0FB21C1048A320" bold="true" pageId="0" pageNumber="13">Figure 2.</emphasis>
Three-dimensional renderings of the circulatory system of BSPG 1991 II 113.
<emphasis id="B83E44DFD803638589A3D1B7A8A3CB9B" bold="true" pageId="0" pageNumber="13">A.</emphasis>
Dorsal view;
<emphasis id="E6F9131ED4E66B87D12C435665C3C51A" bold="true" pageId="0" pageNumber="13">B.</emphasis>
Dorsal view with bones rendered transparent. Abbreviations: af-op, articulation facet for the opisthotic; ccb, canalis caroticus basisphenoidalis; cci, canalis caroticus internus; cnf, canalis nervus facialis; cprnv, canalis pro ramo nervi vidiani; faccb, foramen anterius canalis carotici basisphenoidalis; fpcci, foramen posterius canalis carotici interni; fpcna, foramen posterius canalis nervi abducentis; pbs, parabasisphenoid; pt, pterygoid; stag, stapedial artery groove.
</paragraph>
</caption>
<paragraph id="F13C82811AE0D45409A1743602943F26" pageId="0" pageNumber="13">
<emphasis id="EA6D5A59B82D40AEE6774BB58CE53484" bold="true" pageId="0" pageNumber="13">Epipterygoid.</emphasis>
A large epipterygoid was described on the left side of BSPG 1991 II 130 by
<bibRefCitation id="79985A7A2F7DEC1B2118CECF637B523D" DOI="https://doi.org/10.3374/014.055.0207" author="Havlik, PE" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="201 - 214" refId="B26" refString="Havlik, PE, Joyce, WG, Boehme, M, 2014. Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya. Bulletin of the Peabody Museum of Natural History 55 (2): 201 - 214, DOI: https://doi.org/10.3374/014.055.0207" title="Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya." url="https://doi.org/10.3374/014.055.0207" volume="55" year="2014">Havlik et al. (2014)</bibRefCitation>
, but the
<normalizedToken id="D5F61E464B2B521FE502423D4EE342F6" originalValue="µCT">µCT</normalizedToken>
scans of that specimen show that this piece of bone anteroventral to the mandibular artery foramen actually belongs to the pterygoid (Fig.
<figureCitation id="A5B6D5629C3CA23034AFCE35B573E8BC" captionStart="Figure 3" captionStartId="F3" captionText="Figure 3. Three-dimensional renderings of the left trigeminal area of Allaeochelys libyca (BSPG 1991 II 113) and Carettochelys insculpta (NHMUK 1903.7.10.1). A. Left trigeminal area of Allaeochelys libyca in anterolateral view; B. Close-up on the left trigeminal area of Allaeochelys libyca; C. Left trigeminal area of Carettochelys insculpta in anterolateral view; D. Close-up on the left trigeminal area of Carettochelys insculpta; E. Left trigeminal area of Carettochelys insculpta in anterolateral view with the epipterygoid removed; F. Close-up on the left trigeminal area of Carettochelys insculpta with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in Carettochelys insculpta." figureDoi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13">3</figureCitation>
). The epipterygoid usually lies along the anterior and ventral margins of the foramen nervi trigemini
<emphasis id="79317E87EAA420196B86D688BDDBEBF9" italics="true" pageId="0" pageNumber="13">sensu lato</emphasis>
in other carettochelyids (
<bibRefCitation id="1DD46200DB8F6BE9714D4F5AA2B55F14" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="38ACC3C9BC65B8B3E7E9D306D2DB06D2" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
) and overlies the pterygoid in about the area where
<bibRefCitation id="FB9F5651B3C4A18ACEB04E84FA7465DA" DOI="https://doi.org/10.3374/014.055.0207" author="Havlik, PE" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="201 - 214" refId="B26" refString="Havlik, PE, Joyce, WG, Boehme, M, 2014. Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya. Bulletin of the Peabody Museum of Natural History 55 (2): 201 - 214, DOI: https://doi.org/10.3374/014.055.0207" title="Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya." url="https://doi.org/10.3374/014.055.0207" volume="55" year="2014">Havlik et al. (2014)</bibRefCitation>
drew their epipterygoid. In BSPG 1991 II 130, the area that was indicated as being the epipterygoid by
<bibRefCitation id="98BCD11F439BE0D4E63A65C629E7D4A8" DOI="https://doi.org/10.3374/014.055.0207" author="Havlik, PE" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="201 - 214" refId="B26" refString="Havlik, PE, Joyce, WG, Boehme, M, 2014. Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya. Bulletin of the Peabody Museum of Natural History 55 (2): 201 - 214, DOI: https://doi.org/10.3374/014.055.0207" title="Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya." url="https://doi.org/10.3374/014.055.0207" volume="55" year="2014">Havlik et al. (2014)</bibRefCitation>
has a slightly different, somewhat rougher surface texture than the surrounding bone surfaces exposed along the lower temporal fossa. We consider it likely, based on comparisons of a completely segmented specimen of
<taxonomicName id="228759D1193D8BC07C440EE678542C76" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="817C71AC29E42C999D1EEE4B9783FE97" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
(NHMUK 1903.7.10.1), that this area represents an articulation area for a formerly present but not preserved epipterygoid of BSPG 1991 II 130. Details of this are further given below in the context of descriptions and discussions surrounding the foramen for the mandibular artery.
</paragraph>
<caption id="7C9D46F54862C8E75C9831C5BC588DC3" doi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13" start="Figure 3" startId="F3">
<paragraph id="B56EFF2351D1D5A6DA25AE0EA5BBC426" pageId="0" pageNumber="13">
<emphasis id="58648BB4BB36BCDCCC8F05E8E19A113D" bold="true" pageId="0" pageNumber="13">Figure 3.</emphasis>
Three-dimensional renderings of the left trigeminal area of
<taxonomicName id="A512AECA112E6B8C71ED586BC5DA67BC" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="B11990D41CDB1E2C86AA52313B56C625" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
(BSPG 1991 II 113) and
<taxonomicName id="15ABCCF8BC5EEE4A3BF3706518E466BA" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="F24B095534AD520DBD3A72A79A7CCC2E" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
(NHMUK 1903.7.10.1).
<emphasis id="B558A461E3E6C3C51C069B0F4B4C341F" bold="true" pageId="0" pageNumber="13">A.</emphasis>
Left trigeminal area of
<taxonomicName id="AE6EBE389A7FE196EBE02C7ADA2DB5BF" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="9DE27C57D69CE04B4B46AC3373CFCF76" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
in anterolateral view;
<emphasis id="864119383B508A4E152CF43C8BFE99C1" bold="true" pageId="0" pageNumber="13">B.</emphasis>
Close-up on the left trigeminal area of
<taxonomicName id="B52E99D0C7F4677274740F7F3E2BD670" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="5830D8472B16EA0424217CA413171A56" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
;
<emphasis id="A9C7551640F57D4D550A646F668CAAB4" bold="true" pageId="0" pageNumber="13">C.</emphasis>
Left trigeminal area of
<taxonomicName id="936A95FCB618962156D7B14889DB5182" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="1C89620AB33070600FEFDACA3CCD4CF3" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
in anterolateral view;
<emphasis id="F2F57C95E435FF87DDB30FC375DE6AED" bold="true" pageId="0" pageNumber="13">D.</emphasis>
Close-up on the left trigeminal area of
<taxonomicName id="A8AE6F70248A8D248F7990F5C1584DDC" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="8296C99818EA108B00147B3327379C7D" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
;
<emphasis id="7B466BFCF6411F755C9FECDD6C22B95E" bold="true" pageId="0" pageNumber="13">E.</emphasis>
Left trigeminal area of
<taxonomicName id="AFBF5550484E484590F3A0CFFBCEBC03" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="769D0C1C86C80E6544BCFDBEB8157D3E" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
in anterolateral view with the epipterygoid removed;
<emphasis id="E37FD823F34D496E1E382BAD36AA3C7A" bold="true" pageId="0" pageNumber="13">F.</emphasis>
Close-up on the left trigeminal area of
<taxonomicName id="BD2F4B4BF9AFFA282BC4BC2C0804D744" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="F56255C25EF8314DCE5DD22E5BA74F49" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in
<taxonomicName id="1B3A23C5FC43A2D1EA6D4B7157E119D1" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="00E1BC36F55F01433A9D4ADB1DAD7543" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
.
</paragraph>
</caption>
<paragraph id="77FC8FE5222B7FB1070F31F1EA0B5B1A" pageId="0" pageNumber="13">
<emphasis id="1B5205E0D7EC6C3C8FE71486EFBA2DEC" bold="true" pageId="0" pageNumber="13">Quadrate.</emphasis>
The quadrates are nearly complete, with only minor damage along the anterior and posterior margins of the cavum tympani (Figs
<figureCitation id="E41E789B7F1A12769CB9BE821ACE6861" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1C, D</figureCitation>
,
<figureCitation id="04F1A41224877F58CC0FE67FEB47D8DC" captionStart="Figure 4" captionStartId="F4" captionText="Figure 4. Three-dimensional renderings of the right quadrate of BSPG 1991 II 113. A. Lateral view; B. Posterior view; C. Dorsal view; D. Ventral view. Abbreviations: af-op, articulation facet for opisthotic; af-pro, articulation facet for prootic; af-pt, articulation facet for pterygoid; af-qj, articulation facet for quadratojugal; af-sq, articulation facet for squamosal; ap, antrum postoticum; aqf, anterior quadrate foramen; cm, condylus mandibularis; fam, foramen arteriomandibulare; fpo, fenestra postotica; fst, foramen stapedio-temporalis; ica, incisura columella auris; qf, quadrate fossa." figureDoi="10.3897/fr.27.115046.figure4" httpUri="https://binary.pensoft.net/fig/961960" pageId="0" pageNumber="13">4</figureCitation>
). The quadrate contacts the quadratojugal anteriorly, the prootic anteromedially, the opisthotic posteromedially, and the pterygoid ventromedially (Fig.
<figureCitation id="57F096A034BE11485DE63611562B78ED" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A, B, E, F</figureCitation>
). Posterodorsolaterally, the quadrate forms a mediolaterally expanded articular facet for articulation with the squamosal (Figs
<figureCitation id="975FDBF26F26BE1A09DCD29B953236E1" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A</figureCitation>
,
<figureCitation id="0F5BA2B80B9C278AF05EC05204E82041" captionStart="Figure 4" captionStartId="F4" captionText="Figure 4. Three-dimensional renderings of the right quadrate of BSPG 1991 II 113. A. Lateral view; B. Posterior view; C. Dorsal view; D. Ventral view. Abbreviations: af-op, articulation facet for opisthotic; af-pro, articulation facet for prootic; af-pt, articulation facet for pterygoid; af-qj, articulation facet for quadratojugal; af-sq, articulation facet for squamosal; ap, antrum postoticum; aqf, anterior quadrate foramen; cm, condylus mandibularis; fam, foramen arteriomandibulare; fpo, fenestra postotica; fst, foramen stapedio-temporalis; ica, incisura columella auris; qf, quadrate fossa." figureDoi="10.3897/fr.27.115046.figure4" httpUri="https://binary.pensoft.net/fig/961960" pageId="0" pageNumber="13">4</figureCitation>
). A contact with the supraoccipital is absent, as in other carettochelyids (
<bibRefCitation id="B0F40D45E9863CF39131F7270771AC86" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="7537066BAFC4940EDC0E7E9EB663C69F" DOI="https://doi.org/10.1080/02724634.2017.1335735" author="Danilov, IG" journalOrPublisher="Geologische und Palaeontologische Abhandlungen" pageId="0" pageNumber="13" refId="B12" refString="Danilov, IG, Obraztsova, EM, Chen, W, Jianhua, J, 2017. The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37(4): e1335735. https://doi.org/10.1080/02724634.2017.1335735" title="The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37 (4): e 1335735." url="https://doi.org/10.1080/02724634.2017.1335735" year="2017">Danilov et al. 2017</bibRefCitation>
;
<bibRefCitation id="8CE005309D0735FFA211CABA4A6DBAF9" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
). As the quadrate only forms a short epipterygoid process anteriorly, a contact between the epipterygoid and quadrate was likely absent in BSPG 1991 II 130 or minimal (Fig.
<figureCitation id="EFC3233768575908E93BE18583AE5F26" captionStart="Figure 3" captionStartId="F3" captionText="Figure 3. Three-dimensional renderings of the left trigeminal area of Allaeochelys libyca (BSPG 1991 II 113) and Carettochelys insculpta (NHMUK 1903.7.10.1). A. Left trigeminal area of Allaeochelys libyca in anterolateral view; B. Close-up on the left trigeminal area of Allaeochelys libyca; C. Left trigeminal area of Carettochelys insculpta in anterolateral view; D. Close-up on the left trigeminal area of Carettochelys insculpta; E. Left trigeminal area of Carettochelys insculpta in anterolateral view with the epipterygoid removed; F. Close-up on the left trigeminal area of Carettochelys insculpta with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in Carettochelys insculpta." figureDoi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13">3</figureCitation>
), as in some
<taxonomicName id="044B0C15F4C79881A40EC1F1B0AD1D9E" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="7D19CAF6F9F36295E55F85F00A039F66" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
specimens. The quadrate of BSPG 1991 II 130 forms the lateral and ventrolateral margin of the mandibular artery foramen, and less than half of the processus trochlearis oticum (Figs
<figureCitation id="063306F32041E70119EE75B7203E8B41" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1E</figureCitation>
,
<figureCitation id="AB69A6D320BC77CA89E70098105247AC" captionStart="Figure 3" captionStartId="F3" captionText="Figure 3. Three-dimensional renderings of the left trigeminal area of Allaeochelys libyca (BSPG 1991 II 113) and Carettochelys insculpta (NHMUK 1903.7.10.1). A. Left trigeminal area of Allaeochelys libyca in anterolateral view; B. Close-up on the left trigeminal area of Allaeochelys libyca; C. Left trigeminal area of Carettochelys insculpta in anterolateral view; D. Close-up on the left trigeminal area of Carettochelys insculpta; E. Left trigeminal area of Carettochelys insculpta in anterolateral view with the epipterygoid removed; F. Close-up on the left trigeminal area of Carettochelys insculpta with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in Carettochelys insculpta." figureDoi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13">3</figureCitation>
). Along its ventral surface, anterior to the condylus mandibularis, the quadrate forms a conspicuous foramen of several millimeter width, which leads into a canal that extends dorsally within the quadrate and joins the most anterior aspect of the quadrate fossa (Fig.
<figureCitation id="EF320A861BE45328288AC83945FCEFD7" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B</figureCitation>
). We herein refer to this foramen as the anterior quadrate foramen. The path and location of its canal somewhat resembles that of the canalis chorda tympani quadrati (sensu
<bibRefCitation id="FC614069A505CCD6A04D72BD23362258" author="Gaffney, ES" journalOrPublisher="American Museum Novitates" pageId="0" pageNumber="13" pagination="1 - 33" refId="B20" refString="Gaffney, ES, 1972. An illustrated glossary of turtle skull nomenclature. American Museum Novitates 2486: 1 - 33" title="An illustrated glossary of turtle skull nomenclature." volume="2486" year="1972">Gaffney 1972</bibRefCitation>
), which transmits the chorda tympani branch of the facial nerve (CN VII). However, the chorda tympani canal generally opens along the posterior surface of the quadrate and connects dorsally to the incisura columella auris, which has a direct connection to the facial nerve path via the cavum acustico-jugulare. Here, we are not able to identify any connection between the quadrate canal in BSPG 1991 II 130 and the incisura columella auris or otherwise the cavum acustico-jugulare, and therefore cannot know its precise identity. However, as the foramen is also evident in the extant
<taxonomicName id="9D5258DA999CC6DDD7F8658D5AA33AAC" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="1F12F2EE9CE14C48900455417B204FD0" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
, but absent in the early branching carettochelyid
<taxonomicName id="3D0A2CFACCF1A6AD2CE3CB74A4A6016A" baseAuthorityName="Clark" baseAuthorityYear="1932" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira pulchra" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="pulchra">
<emphasis id="06015CD42C9EFCB384379F3228DDD44C" italics="true" pageId="0" pageNumber="13">Anosteira pulchra</emphasis>
</taxonomicName>
for which we have CT scans to ascertain this statement, we provide a new name for the structure as a potential shared character of derived carettochelyids. The quadrate forms a low, ventrally oriented mandibular condyle, of which the lateral articular surface is about twice the size of the medial one (Figs
<figureCitation id="834E78259FEA64AA532C7F0B8F4A95F6" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B</figureCitation>
,
<figureCitation id="CAA191379F69714EF26A66D029CBD165" captionStart="Figure 4" captionStartId="F4" captionText="Figure 4. Three-dimensional renderings of the right quadrate of BSPG 1991 II 113. A. Lateral view; B. Posterior view; C. Dorsal view; D. Ventral view. Abbreviations: af-op, articulation facet for opisthotic; af-pro, articulation facet for prootic; af-pt, articulation facet for pterygoid; af-qj, articulation facet for quadratojugal; af-sq, articulation facet for squamosal; ap, antrum postoticum; aqf, anterior quadrate foramen; cm, condylus mandibularis; fam, foramen arteriomandibulare; fpo, fenestra postotica; fst, foramen stapedio-temporalis; ica, incisura columella auris; qf, quadrate fossa." figureDoi="10.3897/fr.27.115046.figure4" httpUri="https://binary.pensoft.net/fig/961960" pageId="0" pageNumber="13">4</figureCitation>
). The two articular facets are separated by a deep and relatively wide sulcus (Fig.
<figureCitation id="908CFE08286C60044FE9C46CF7109A19" captionStart="Figure 4" captionStartId="F4" captionText="Figure 4. Three-dimensional renderings of the right quadrate of BSPG 1991 II 113. A. Lateral view; B. Posterior view; C. Dorsal view; D. Ventral view. Abbreviations: af-op, articulation facet for opisthotic; af-pro, articulation facet for prootic; af-pt, articulation facet for pterygoid; af-qj, articulation facet for quadratojugal; af-sq, articulation facet for squamosal; ap, antrum postoticum; aqf, anterior quadrate foramen; cm, condylus mandibularis; fam, foramen arteriomandibulare; fpo, fenestra postotica; fst, foramen stapedio-temporalis; ica, incisura columella auris; qf, quadrate fossa." figureDoi="10.3897/fr.27.115046.figure4" httpUri="https://binary.pensoft.net/fig/961960" pageId="0" pageNumber="13">4B</figureCitation>
). Anterolateral to the articular process, the quadrate extends with a vertical, sheeted process that is ventrally projecting from the margin of the cavum tympani, and which effectively forms a lateral wall to the most posterior portion of the lower temporal fossa. This sheeted process anteriorly contacted the quadratojugal (
<bibRefCitation id="1C3070CA6F90515C28956B94A28DD4D2" DOI="https://doi.org/10.3374/014.055.0207" author="Havlik, PE" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="201 - 214" refId="B26" refString="Havlik, PE, Joyce, WG, Boehme, M, 2014. Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya. Bulletin of the Peabody Museum of Natural History 55 (2): 201 - 214, DOI: https://doi.org/10.3374/014.055.0207" title="Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya." url="https://doi.org/10.3374/014.055.0207" volume="55" year="2014">Havlik et al. 2014</bibRefCitation>
), but the respective quadratojugal piece is now disarticulated. Within the upper temporal fossa, the quadrate forms the lateral margin of the foramen stapedio-temporale (Fig.
<figureCitation id="70C45C54833149A4B73F9B20075443A2" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A</figureCitation>
). The foramen leads into the canalis stapedio-temporalis, which is notably short, mostly oriented mediolaterally, and laterally bordered by the quadrate. The canalis stapedio-temporalis leads into the cavum acustico-jugulare, of which the quadrate forms the lateral wall. The medial surface of the quadrate forms an imprint that allows to determine the path of the stapedial artery. A large groove extends anteriorly and slightly dorsally from the fenestra postotica and, anterodorsal to the incisura columella auris, abruptly curves to extend ventrally and join the mandibular artery foramen. Dorsally and at about mid-length between the incisura columella auris and mandibular artery foramen, the quadrate forms a low ridge, which with the prootic collectively defines a passage for the stapedial artery from the cavum acustico-jugulare to the canalis stapedio-temporalis. It is likely that the split between the stapedial and mandibular artery occurred at that level, with the stapedial artery extending laterally through the canalis stapedio-temporalis and the mandibular artery curving ventrally to exit the skull by means of the foramen cavernosum. Laterally, the quadrate forms most of the cavum tympani, to the exception of the most anterior margin that is formed by the quadratojugal (Figs
<figureCitation id="98EE86620D6B4424ED531540239BCD9A" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1C, D</figureCitation>
,
<figureCitation id="6401FE23672D4587D4B5D537BDB9F4F0" captionStart="Figure 4" captionStartId="F4" captionText="Figure 4. Three-dimensional renderings of the right quadrate of BSPG 1991 II 113. A. Lateral view; B. Posterior view; C. Dorsal view; D. Ventral view. Abbreviations: af-op, articulation facet for opisthotic; af-pro, articulation facet for prootic; af-pt, articulation facet for pterygoid; af-qj, articulation facet for quadratojugal; af-sq, articulation facet for squamosal; ap, antrum postoticum; aqf, anterior quadrate foramen; cm, condylus mandibularis; fam, foramen arteriomandibulare; fpo, fenestra postotica; fst, foramen stapedio-temporalis; ica, incisura columella auris; qf, quadrate fossa." figureDoi="10.3897/fr.27.115046.figure4" httpUri="https://binary.pensoft.net/fig/961960" pageId="0" pageNumber="13">4A</figureCitation>
), as in other carettochelyids (
<bibRefCitation id="9E1218EBC23C53E471CA0827CB891EB0" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="2A35B81D582BDE0D7F1F63951970E643" DOI="https://doi.org/10.1080/02724634.2017.1335735" author="Danilov, IG" journalOrPublisher="Geologische und Palaeontologische Abhandlungen" pageId="0" pageNumber="13" refId="B12" refString="Danilov, IG, Obraztsova, EM, Chen, W, Jianhua, J, 2017. The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37(4): e1335735. https://doi.org/10.1080/02724634.2017.1335735" title="The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37 (4): e 1335735." url="https://doi.org/10.1080/02724634.2017.1335735" year="2017">Danilov et al. 2017</bibRefCitation>
;
<bibRefCitation id="4C55A4B57CA3E70A664BD1B8626EF64D" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
). The quadrate also completely encloses the incisura columella auris and forms a small antrum postoticum (Figs
<figureCitation id="DE793DFB29883DF1EBF0B0AE06EBC7B7" captionStart="Figure 3" captionStartId="F3" captionText="Figure 3. Three-dimensional renderings of the left trigeminal area of Allaeochelys libyca (BSPG 1991 II 113) and Carettochelys insculpta (NHMUK 1903.7.10.1). A. Left trigeminal area of Allaeochelys libyca in anterolateral view; B. Close-up on the left trigeminal area of Allaeochelys libyca; C. Left trigeminal area of Carettochelys insculpta in anterolateral view; D. Close-up on the left trigeminal area of Carettochelys insculpta; E. Left trigeminal area of Carettochelys insculpta in anterolateral view with the epipterygoid removed; F. Close-up on the left trigeminal area of Carettochelys insculpta with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in Carettochelys insculpta." figureDoi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13">3A</figureCitation>
,
<figureCitation id="236712451BD425821EF78F2CD43D36E6" captionStart="Figure 4" captionStartId="F4" captionText="Figure 4. Three-dimensional renderings of the right quadrate of BSPG 1991 II 113. A. Lateral view; B. Posterior view; C. Dorsal view; D. Ventral view. Abbreviations: af-op, articulation facet for opisthotic; af-pro, articulation facet for prootic; af-pt, articulation facet for pterygoid; af-qj, articulation facet for quadratojugal; af-sq, articulation facet for squamosal; ap, antrum postoticum; aqf, anterior quadrate foramen; cm, condylus mandibularis; fam, foramen arteriomandibulare; fpo, fenestra postotica; fst, foramen stapedio-temporalis; ica, incisura columella auris; qf, quadrate fossa." figureDoi="10.3897/fr.27.115046.figure4" httpUri="https://binary.pensoft.net/fig/961960" pageId="0" pageNumber="13">4A</figureCitation>
), which extends posterodorsolaterally through the quadrate and squamosal, as in
<taxonomicName id="A287756C3E9A907D6BC7CDBC2719C5D4" baseAuthorityName="Clark" baseAuthorityYear="1932" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira pulchra" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="pulchra">
<emphasis id="66F639DEE02E12303D746656DB0E1670" italics="true" pageId="0" pageNumber="13">Anosteira pulchra</emphasis>
</taxonomicName>
(
<bibRefCitation id="FC662CF3F77FA221717E2813ED09BEF3" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
) and
<taxonomicName id="7100F7F5355707A6453AD836010DC3AC" authorityName="Chow &amp; Liu" authorityYear="1955" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira maomingensis" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="maomingensis">
<emphasis id="4347A15EC44406C9ACE5AF98BDA2FA5F" italics="true" pageId="0" pageNumber="13">Anosteira maomingensis</emphasis>
</taxonomicName>
(
<bibRefCitation id="1A27749A02969E2C6D51759E58F30CC6" DOI="https://doi.org/10.1080/02724634.2017.1335735" author="Danilov, IG" journalOrPublisher="Geologische und Palaeontologische Abhandlungen" pageId="0" pageNumber="13" refId="B12" refString="Danilov, IG, Obraztsova, EM, Chen, W, Jianhua, J, 2017. The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37(4): e1335735. https://doi.org/10.1080/02724634.2017.1335735" title="The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37 (4): e 1335735." url="https://doi.org/10.1080/02724634.2017.1335735" year="2017">Danilov et al. 2017</bibRefCitation>
). Along its posterior surface, the quadrate forms the quadrate fossa (Fig.
<figureCitation id="69FC8F55732FB67C86EB95DEA78DB305" captionStart="Figure 4" captionStartId="F4" captionText="Figure 4. Three-dimensional renderings of the right quadrate of BSPG 1991 II 113. A. Lateral view; B. Posterior view; C. Dorsal view; D. Ventral view. Abbreviations: af-op, articulation facet for opisthotic; af-pro, articulation facet for prootic; af-pt, articulation facet for pterygoid; af-qj, articulation facet for quadratojugal; af-sq, articulation facet for squamosal; ap, antrum postoticum; aqf, anterior quadrate foramen; cm, condylus mandibularis; fam, foramen arteriomandibulare; fpo, fenestra postotica; fst, foramen stapedio-temporalis; ica, incisura columella auris; qf, quadrate fossa." figureDoi="10.3897/fr.27.115046.figure4" httpUri="https://binary.pensoft.net/fig/961960" pageId="0" pageNumber="13">4B</figureCitation>
), as in other carettochelyids (
<bibRefCitation id="AA1B1EB9EC7E1C222CC021AEC9BB434A" author="Harrassowitz, H" journalOrPublisher="Abhandlungen der Hessischen Geologischen Landesanstalt" pageId="0" pageNumber="13" pagination="132 - 239" refId="B25" refString="Harrassowitz, H, 1922. Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung. Abhandlungen der Hessischen Geologischen Landesanstalt 6: 132 - 239" title="Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung." volume="6" year="1922">Harrassowitz 1922</bibRefCitation>
;
<bibRefCitation id="0AF5C89CE6C13F2F198685E59C4C2951" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="B94F36FE8812940712237E5AAF89D44E" DOI="https://doi.org/10.1080/02724634.2017.1335735" author="Danilov, IG" journalOrPublisher="Geologische und Palaeontologische Abhandlungen" pageId="0" pageNumber="13" refId="B12" refString="Danilov, IG, Obraztsova, EM, Chen, W, Jianhua, J, 2017. The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37(4): e1335735. https://doi.org/10.1080/02724634.2017.1335735" title="The cranial morphology of Anosteira maomingensis (Testudines, Pan-Carettochelys) and the evolution of pan-carettochelyid turtles. Journal of Vertebrate Paleontology 37 (4): e 1335735." url="https://doi.org/10.1080/02724634.2017.1335735" year="2017">Danilov et al. 2017</bibRefCitation>
;
<bibRefCitation id="14DC4FA3380FE326AF9367535C9AFFB9" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
). The quadrate fossa is broad and deep, as in more derived members of the clade (
<bibRefCitation id="F65CAD59D3533948E02F3E09CCB96CDD" DOI="https://doi.org/10.3374/014.055.0102" author="Joyce, WG" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="3 - 33" refId="B28" refString="Joyce, WG, 2014. A review of the fossil record of turtles of the clade Pan-Carettochelys. Bulletin of the Peabody Museum of Natural History 55 (1): 3 - 33, DOI: https://doi.org/10.3374/014.055.0102" title="A review of the fossil record of turtles of the clade Pan-Carettochelys." url="https://doi.org/10.3374/014.055.0102" volume="55" year="2014">Joyce 2014</bibRefCitation>
).
</paragraph>
<caption id="453CD9D1C35F4704C7C635D2D928D777" doi="10.3897/fr.27.115046.figure4" httpUri="https://binary.pensoft.net/fig/961960" pageId="0" pageNumber="13" start="Figure 4" startId="F4">
<paragraph id="59878706A1D092A136B8E3F1F46AE88D" pageId="0" pageNumber="13">
<emphasis id="DAC63D071E1A503C0878ECCE143C8AEB" bold="true" pageId="0" pageNumber="13">Figure 4.</emphasis>
Three-dimensional renderings of the right quadrate of BSPG 1991 II 113.
<emphasis id="0B243F93FA4DBEDDDB8D0CEE69AB4F12" bold="true" pageId="0" pageNumber="13">A.</emphasis>
Lateral view;
<emphasis id="8FAE9027600D155DBC4ED9DA76767AF5" bold="true" pageId="0" pageNumber="13">B.</emphasis>
Posterior view;
<emphasis id="69847A60FAD8CC43C0D5E7BCED90C9C4" bold="true" pageId="0" pageNumber="13">C.</emphasis>
Dorsal view;
<emphasis id="5991749CBFB6F59FFFB3E3919749EC3D" bold="true" pageId="0" pageNumber="13">D.</emphasis>
Ventral view. Abbreviations: af-op, articulation facet for opisthotic; af-pro, articulation facet for prootic; af-pt, articulation facet for pterygoid; af-qj, articulation facet for quadratojugal; af-sq, articulation facet for squamosal; ap, antrum postoticum; aqf, anterior quadrate foramen; cm, condylus mandibularis; fam, foramen arteriomandibulare; fpo, fenestra postotica; fst, foramen stapedio-temporalis; ica, incisura columella auris; qf, quadrate fossa.
</paragraph>
</caption>
<paragraph id="792C933FD2C7D139BEF51B544B1F902C" pageId="0" pageNumber="13">
<emphasis id="598BB793313E2621B506A3C26816135F" bold="true" pageId="0" pageNumber="13">Prootic.</emphasis>
The prootics are intact in BSPG 1991 II 130. Within the upper temporal fossa, the prootic contacts the parietal anteromedially, the supraoccipital posteromedially, the quadrate laterally, and the opisthotic posteriorly, and forms the medial margin of the foramen stapedio-temporale (Fig.
<figureCitation id="D6943995751E61808DFF36B9E427B686" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A</figureCitation>
). Ventrally, the prootic contacts the parabasisphenoid medially, the pterygoid ventrally, the quadrate laterally, and, likely, the epipterygoid anteroventrolaterally (Figs
<figureCitation id="17C79D4BA05ACDDFDA528A5FE7566BD8" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B, E</figureCitation>
,
<figureCitation id="10499D803D0EB14885E3EE960B844C7C" captionStart="Figure 3" captionStartId="F3" captionText="Figure 3. Three-dimensional renderings of the left trigeminal area of Allaeochelys libyca (BSPG 1991 II 113) and Carettochelys insculpta (NHMUK 1903.7.10.1). A. Left trigeminal area of Allaeochelys libyca in anterolateral view; B. Close-up on the left trigeminal area of Allaeochelys libyca; C. Left trigeminal area of Carettochelys insculpta in anterolateral view; D. Close-up on the left trigeminal area of Carettochelys insculpta; E. Left trigeminal area of Carettochelys insculpta in anterolateral view with the epipterygoid removed; F. Close-up on the left trigeminal area of Carettochelys insculpta with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in Carettochelys insculpta." figureDoi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13">3</figureCitation>
). The prootic forms the greater half of the processus trochlearis oticum, which is medially continuous with a prominent ridge formed by the descending process of the parietal (Figs
<figureCitation id="2D5276FC4901C3EDF905736CC60A570A" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B, E</figureCitation>
,
<figureCitation id="C879E89352AC3C410EEBB89134B258A4" captionStart="Figure 3" captionStartId="F3" captionText="Figure 3. Three-dimensional renderings of the left trigeminal area of Allaeochelys libyca (BSPG 1991 II 113) and Carettochelys insculpta (NHMUK 1903.7.10.1). A. Left trigeminal area of Allaeochelys libyca in anterolateral view; B. Close-up on the left trigeminal area of Allaeochelys libyca; C. Left trigeminal area of Carettochelys insculpta in anterolateral view; D. Close-up on the left trigeminal area of Carettochelys insculpta; E. Left trigeminal area of Carettochelys insculpta in anterolateral view with the epipterygoid removed; F. Close-up on the left trigeminal area of Carettochelys insculpta with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in Carettochelys insculpta." figureDoi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13">3</figureCitation>
). The anterior margin of the process overhangs the lower temporal fossa and forms a broadly concave surface for the adductor musculature and associated tendons. Within the lower temporal fossa, the prootic forms the posterior margin of the foramen nervi trigemini
<emphasis id="61A6CDA1E662A0AA1F7BCAF883A9C977" italics="true" pageId="0" pageNumber="13">sensu stricto</emphasis>
, i.e., the opening through which the maxillary and mandibular nerve rami of the trigeminal nerve system pass (&quot;external trigeminal foramen&quot; of
<bibRefCitation id="9AAC91DDEA6DAA33749F23346660F4B2" DOI="https://doi.org/10.1093/zoolinnean/zlz063" author="Evers, SW" journalOrPublisher="Zoological Journal of the Linnean Society" pageId="0" pageNumber="13" pagination="800 - 828" refId="B16" refString="Evers, SW, Neenan, JM, Ferreira, GS, Werneburg, I, Barrett, PM, Benson, RB, 2019. Neurovascular anatomy of the protostegid turtle Rhinochelys pulchriceps and comparisons of membranous and endosseous labyrinth shape in an extant turtle. Zoological Journal of the Linnean Society 187 (3): 800 - 828, DOI: https://doi.org/10.1093/zoolinnean/zlz063" title="Neurovascular anatomy of the protostegid turtle Rhinochelys pulchriceps and comparisons of membranous and endosseous labyrinth shape in an extant turtle." url="https://doi.org/10.1093/zoolinnean/zlz063" volume="187" year="2019">Evers et al. 2019</bibRefCitation>
), and the medial margin of the mandibular artery foramen, which was labelled as the
<normalizedToken id="ADA62170E03E3DE23BDBA80DB4B26AE9" originalValue="“posterior”">&quot;posterior&quot;</normalizedToken>
foramen nervi trigemini by
<bibRefCitation id="6CCBFE85D125C6F1A579EC33A99AFB2F" DOI="https://doi.org/10.3374/014.055.0207" author="Havlik, PE" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="201 - 214" refId="B26" refString="Havlik, PE, Joyce, WG, Boehme, M, 2014. Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya. Bulletin of the Peabody Museum of Natural History 55 (2): 201 - 214, DOI: https://doi.org/10.3374/014.055.0207" title="Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya." url="https://doi.org/10.3374/014.055.0207" volume="55" year="2014">Havlik et al. (2014)</bibRefCitation>
(Figs
<figureCitation id="169B0A4D986435FC7C153769B9061F67" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1E</figureCitation>
,
<figureCitation id="CF2366AE65E44A2F3C89A8910F2A5072" captionStart="Figure 3" captionStartId="F3" captionText="Figure 3. Three-dimensional renderings of the left trigeminal area of Allaeochelys libyca (BSPG 1991 II 113) and Carettochelys insculpta (NHMUK 1903.7.10.1). A. Left trigeminal area of Allaeochelys libyca in anterolateral view; B. Close-up on the left trigeminal area of Allaeochelys libyca; C. Left trigeminal area of Carettochelys insculpta in anterolateral view; D. Close-up on the left trigeminal area of Carettochelys insculpta; E. Left trigeminal area of Carettochelys insculpta in anterolateral view with the epipterygoid removed; F. Close-up on the left trigeminal area of Carettochelys insculpta with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in Carettochelys insculpta." figureDoi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13">3</figureCitation>
). These foramina and the associated canalis cavernosus are described in conjunction further below, as the morphology seen in
<taxonomicName id="6FD87A1E4CF7D6780D3824054F0CEF87" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="61277E5F30451C0A5E97708AEA811924" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
is quite unusual. Within the braincase, the prootic anteriorly forms the posterior portion of a deep cavity, which collectively with the parietal encapsulates the cerebral hemisphere, which appears to be notably large, as has also been reported for extant trionychids (
<bibRefCitation id="F86BFCA4CC1D236FC5C41189AD30A218" DOI="https://doi.org/10.1007/978-3-031-13983-3_4" author="Ferreira, GS" editor="Dozo, MT" journalOrPublisher="Springer International Publishing, Cham" pageId="0" pageNumber="13" pagination="79 - 121" refId="B19" refString="Ferreira, GS, Werneburg, I, Lautenschlager, S, Evers, SW, 2023. Contrasting brains and bones: neuroanatomical evolution of turtles (Testudinata). In: Dozo, MT, Paulina-Carabajal, A, Macrini, TE, Walsh, S, Eds., Paleoneurology of amniotes: new directions in the study of fossil endocasts. Springer International Publishing, Cham: 79 - 121, DOI: https://doi.org/10.1007/978-3-031-13983-3_4" title="Contrasting brains and bones: neuroanatomical evolution of turtles (Testudinata)." url="https://doi.org/10.1007/978-3-031-13983-3_4" volumeTitle="Paleoneurology of amniotes: new directions in the study of fossil endocasts." year="2023">Ferreira et al. 2023</bibRefCitation>
). Posterior to the foramen nervi trigemini
<emphasis id="F7F20BE00D999BD1A263A95C3D1495D5" italics="true" pageId="0" pageNumber="13">sensu stricto</emphasis>
of BSPG 1991 II 130, and ventral to the cerebral hemisphere imprints, the course of the trigeminal nerve tissue can be inferred to pass along the anteromedial surface of the prootic, which walls a broad cavum epiptericum. On its medial surface, the prootic forms the fenestra acustico-facialis, but the latter is incompletely preserved as portions of the prootic are missing posteromedially. Within the fenestra acustico-facialis, only the medial foramen of the canalis nervus facialis is fully preserved. The canalis nervus facialis extends laterally through the prootic and joins the medial margin of the cavum acustico-jugulare. The canal is extremely large in BSPG 1991 II 130. The canalis pro ramo nervi vidiani branches off the canalis nervus facialis just medial to the latter contact and extends ventromedially through the prootic and pterygoid to join the canalis caroticus internus (Fig.
<figureCitation id="4B9A87817C6B33F7A3A464EEBFCA35A5" captionStart="Figure 2" captionStartId="F2" captionText="Figure 2. Three-dimensional renderings of the circulatory system of BSPG 1991 II 113. A. Dorsal view; B. Dorsal view with bones rendered transparent. Abbreviations: af-op, articulation facet for the opisthotic; ccb, canalis caroticus basisphenoidalis; cci, canalis caroticus internus; cnf, canalis nervus facialis; cprnv, canalis pro ramo nervi vidiani; faccb, foramen anterius canalis carotici basisphenoidalis; fpcci, foramen posterius canalis carotici interni; fpcna, foramen posterius canalis nervi abducentis; pbs, parabasisphenoid; pt, pterygoid; stag, stapedial artery groove." figureDoi="10.3897/fr.27.115046.figure2" httpUri="https://binary.pensoft.net/fig/961958" pageId="0" pageNumber="13">2</figureCitation>
), which is the common condition in carettochelyids (
<bibRefCitation id="B2669FC83E1F103C9AB540C0BC39551F" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
;
<bibRefCitation id="D74B780218B15E3F530E12757E5EF50E" DOI="https://doi.org/10.7717/peerj.10475" author="Rollot, Y" journalOrPublisher="BMC Evolutionary Biology" pageId="0" pageNumber="13" refId="B41" refString="Rollot, Y, Evers, SW, Joyce, WG, 2021a. A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e10475. https://doi.org/10.7717/peerj.10475" title="A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e 10475." url="https://doi.org/10.7717/peerj.10475" year="2021 a">Rollot et al. 2021a</bibRefCitation>
). In BSPG 1991 II 130, a likely vidian nerve canal splits from the canalis caroticus internus at the level of its contact with the canalis pro ramo nervi vidiani and extends anteroventrally through the pterygoid. The preserved portion of this proposed vidian canal is, however, extremely short because of the damage that affects the anteroventral region of the cranium. The location of this canal within the pterygoid in that area of the cranium is nevertheless highly indicative of a canalis nervus vidianus. The preserved aspects of the facial nerve pattern in
<taxonomicName id="F5F01667A7B8425A422EFECD5D6F8AB5" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="8CAEFB65374EB237590A0E3A0D468673" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
are nevertheless very similar to that of other carettochelyids (
<bibRefCitation id="413F9A24D7CFD3BE02CE7821558961D8" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
;
<bibRefCitation id="61F9D519C152E75358097188EFA6D426" DOI="https://doi.org/10.7717/peerj.10475" author="Rollot, Y" journalOrPublisher="BMC Evolutionary Biology" pageId="0" pageNumber="13" refId="B41" refString="Rollot, Y, Evers, SW, Joyce, WG, 2021a. A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e10475. https://doi.org/10.7717/peerj.10475" title="A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e 10475." url="https://doi.org/10.7717/peerj.10475" year="2021 a">Rollot et al. 2021a</bibRefCitation>
). Canals and foramina for the vestibulocochlear nerves (CN VIII) are mostly lacking and only the ventral margin of one foramen remains preserved within the fenestra acustico-facialis, just anterodorsal to the medial foramen for the facial nerve canal. The prootic otherwise forms the anterior half of the endosseous labyrinth, the anterior half of the anterior semicircular canal, and the anterior half of the fenestra ovalis. The anterior half of the lateral semicircular canal is not fully enclosed by bone, and the prootic only forms the lateral margin of a groove that contained the anterior portion of the lateral semicircular duct. Lateral to the fenestra ovalis, there is no posterior recess in the prootic, as in
<taxonomicName id="B66DE36C9686D2B287819107F1915BE6" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="E6BFEA77E622F8A4C039CAE54F7CA943" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
. The prootic also forms the anteromedial wall of the cavum acustico-jugulare and the medial half of the canalis stapedio-temporalis. The foramen nervi trigemini
<emphasis id="1A23DC27859995C2E6489013100FE032" italics="true" pageId="0" pageNumber="13">sensu stricto</emphasis>
(see above) is not truly preserved in BSPG 1991 II 130. Although there is an anteriorly concave notch in the anterior surface of the prootic, this likely represents parts of the prootic surface that forms the cavum epiptericum. The remainder of the foramen was likely formed by the epipterygoid, and not by the parietal. This can be inferred as the posterior end of the descending process of the parietal is completely preserved on the right side of BSPG 1991 II 130. Here, the epipterygoid articulated with a small anteroventrally protruding bump of the prootic (Fig.
<figureCitation id="55595F8A9AFA4E325C8C7F4EBC98F288" captionStart="Figure 3" captionStartId="F3" captionText="Figure 3. Three-dimensional renderings of the left trigeminal area of Allaeochelys libyca (BSPG 1991 II 113) and Carettochelys insculpta (NHMUK 1903.7.10.1). A. Left trigeminal area of Allaeochelys libyca in anterolateral view; B. Close-up on the left trigeminal area of Allaeochelys libyca; C. Left trigeminal area of Carettochelys insculpta in anterolateral view; D. Close-up on the left trigeminal area of Carettochelys insculpta; E. Left trigeminal area of Carettochelys insculpta in anterolateral view with the epipterygoid removed; F. Close-up on the left trigeminal area of Carettochelys insculpta with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in Carettochelys insculpta." figureDoi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13">3A, B</figureCitation>
), which currently prohibits the parietal to enter the trigeminal foramen margin. In the extant
<taxonomicName id="D47F62A11A652D965AA5EBEC7535D662" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="90CBA98A405D7331BEBE5574F321C7AF" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
, an exact same bump-like process serves as an articular process for a posterodorsal process of the epipterygoid, which excludes the parietal from the foramen nervi trigemini
<emphasis id="BBD0DB916A0EE9B59EA94B3364E1CF84" italics="true" pageId="0" pageNumber="13">sensu stricto.</emphasis>
Below, we argue that the trigeminal foramen
<emphasis id="5DB50984CF00A526CB9FE8D5D6071D5E" italics="true" pageId="0" pageNumber="13">sensu stricto</emphasis>
was likely confluent with an opening for the mandibular artery, which is closely associated with the canalis cavernosus. This canal of turtles is a result of their basicranial evolution:
<taxonomicName id="7E5241D9253F8B3753893FFE4FFDDBE9" class="Reptilia" higherTaxonomySource="GBIF" kingdom="Animalia" lsidName="" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="order">Testudines</taxonomicName>
have modified their cranioquadrate space during their early basicranial evolution (e.g.,
<bibRefCitation id="90C3FB447178615D93728D944169BAFE" author="Gaffney, ES" journalOrPublisher="Bulletin of the American Museum of Natural History" pageId="0" pageNumber="13" pagination="1 - 263" refId="B23" refString="Gaffney, ES, 1990. The comparative osteology of the Triassic turtle Proganochelys. Bulletin of the American Museum of Natural History 194: 1 - 263" title="The comparative osteology of the Triassic turtle Proganochelys." volume="194" year="1990">Gaffney 1990</bibRefCitation>
;
<bibRefCitation id="D4918E825055AB2A471CD68798C2A1AD" author="Sterli, J" journalOrPublisher="Acta Palaeontologica Polonica" pageId="0" pageNumber="13" pagination="675 - 694" refId="B46" refString="Sterli, J, Joyce, WG, 2007. The cranial anatomy of the Early Jurassic turtle Kayentachelys aprix. Acta Palaeontologica Polonica 52 (4): 675 - 694" title="The cranial anatomy of the Early Jurassic turtle Kayentachelys aprix." volume="52" year="2007">Sterli and Joyce 2007</bibRefCitation>
;
<bibRefCitation id="7B36C8023BCD46356748498FF43CC403" DOI="https://doi.org/10.1098/rspb.2008.1429" author="Anquetin, J" journalOrPublisher="Proceedings of the Royal Society B: Biological Sciences" pageId="0" pageNumber="13" pagination="879 - 886" refId="B3" refString="Anquetin, J, Barrett, PM, Jones, ME, Moore-Fay, S, Evans, SE, 2009. A new stem turtle from the Middle Jurassic of Scotland: new insights into the evolution and palaeoecology of basal turtles. Proceedings of the Royal Society B: Biological Sciences 276 (1658): 879 - 886, DOI: https://doi.org/10.1098/rspb.2008.1429" title="A new stem turtle from the Middle Jurassic of Scotland: new insights into the evolution and palaeoecology of basal turtles." url="https://doi.org/10.1098/rspb.2008.1429" volume="276" year="2009">Anquetin et al. 2009</bibRefCitation>
;
<bibRefCitation id="E2FDB71BCA1C078DFCDA737A22FBBAD1" DOI="https://doi.org/10.1080/02724631003617597" author="Sterli, J" journalOrPublisher="Journal of Vertebrate Paleontology" pageId="0" pageNumber="13" pagination="351 - 366" refId="B45" refString="Sterli, J, de la Fuente, MS, 2010. Anatomy of Condorchelys antiqua Sterli, 2008, and the origin of the modern jaw closure mechanism in turtles. Journal of Vertebrate Paleontology 30 (2): 351 - 366, DOI: https://doi.org/10.1080/02724631003617597" title="Anatomy of Condorchelys antiqua Sterli, 2008, and the origin of the modern jaw closure mechanism in turtles." url="https://doi.org/10.1080/02724631003617597" volume="30" year="2010">Sterli and de la Fuente 2010</bibRefCitation>
;
<bibRefCitation id="CA87ABA99573272A2C0342443CEA6144" DOI="https://doi.org/10.1186/1471-2148-13-203" author="Rabi, M" journalOrPublisher="BMC Evolutionary Biology" pageId="0" pageNumber="13" pagination="1 - 29" refId="B39" refString="Rabi, M, Zhou, CF, Wings, O, Ge, S, Joyce, WG, 2013. A new xinjiangchelyid turtle from the Middle Jurassic of Xinjiang, China and the evolution of the basipterygoid process in Mesozoic turtles. BMC Evolutionary Biology 13 (1): 1 - 29, DOI: https://doi.org/10.1186/1471-2148-13-203" title="A new xinjiangchelyid turtle from the Middle Jurassic of Xinjiang, China and the evolution of the basipterygoid process in Mesozoic turtles." url="https://doi.org/10.1186/1471-2148-13-203" volume="13" year="2013">Rabi et al. 2013</bibRefCitation>
;
<bibRefCitation id="18E546059BAF11007EEDA6B71B09028A" DOI="https://doi.org/10.1038/s41598-020-62179-5" author="Ferreira, GS" journalOrPublisher="Scientific Reports" pageId="0" pageNumber="13" pagination="1 - 11" refId="B18" refString="Ferreira, GS, Lautenschlager, S, Evers, SW, Pfaff, C, Kriwet, J, Raselli, I, Werneburg, I, 2020. Feeding biomechanics suggests progressive correlation of skull architecture and neck evolution in turtles. Scientific Reports 10 (1): 1 - 11, DOI: https://doi.org/10.1038/s41598-020-62179-5" title="Feeding biomechanics suggests progressive correlation of skull architecture and neck evolution in turtles." url="https://doi.org/10.1038/s41598-020-62179-5" volume="10" year="2020">Ferreira et al. 2020</bibRefCitation>
), thereby trapping the lateral head vein in a canal called the canalis cavernosus (
<bibRefCitation id="E8AB8285A20C6B462413A65689895365" author="Gaffney, ES" journalOrPublisher="Bulletin of the American Museum of Natural History" pageId="0" pageNumber="13" pagination="65 - 376" refId="B22" refString="Gaffney, ES, 1979. Comparative cranial morphology of recent and fossil turtles. Bulletin of the American Museum of Natural History 164: 65 - 376" title="Comparative cranial morphology of recent and fossil turtles." volume="164" year="1979">Gaffney 1979</bibRefCitation>
), which extends from the anterior aspect of the cavum acustico-jugulare between the pterygoid, quadrate and prootic into the secondary braincase of turtles, where the lateral head vein continues medial to the secondary braincase wall that is generally formed by the pterygoid and parietal (
<bibRefCitation id="E9F51153E58CFF453264220BF7AA11CF" author="Gaffney, ES" journalOrPublisher="Bulletin of the American Museum of Natural History" pageId="0" pageNumber="13" pagination="65 - 376" refId="B22" refString="Gaffney, ES, 1979. Comparative cranial morphology of recent and fossil turtles. Bulletin of the American Museum of Natural History 164: 65 - 376" title="Comparative cranial morphology of recent and fossil turtles." volume="164" year="1979">Gaffney 1979</bibRefCitation>
;
<bibRefCitation id="EDA9CCBCE935B56F67A4EB4D35919BDB" DOI="https://doi.org/10.1093/zoolinnean/zlz063" author="Evers, SW" journalOrPublisher="Zoological Journal of the Linnean Society" pageId="0" pageNumber="13" pagination="800 - 828" refId="B16" refString="Evers, SW, Neenan, JM, Ferreira, GS, Werneburg, I, Barrett, PM, Benson, RB, 2019. Neurovascular anatomy of the protostegid turtle Rhinochelys pulchriceps and comparisons of membranous and endosseous labyrinth shape in an extant turtle. Zoological Journal of the Linnean Society 187 (3): 800 - 828, DOI: https://doi.org/10.1093/zoolinnean/zlz063" title="Neurovascular anatomy of the protostegid turtle Rhinochelys pulchriceps and comparisons of membranous and endosseous labyrinth shape in an extant turtle." url="https://doi.org/10.1093/zoolinnean/zlz063" volume="187" year="2019">Evers et al. 2019</bibRefCitation>
;
<bibRefCitation id="B272894A837B809B3F917EB9E482EE70" DOI="https://doi.org/10.7717/peerj.10475" author="Rollot, Y" journalOrPublisher="BMC Evolutionary Biology" pageId="0" pageNumber="13" refId="B41" refString="Rollot, Y, Evers, SW, Joyce, WG, 2021a. A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e10475. https://doi.org/10.7717/peerj.10475" title="A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e 10475." url="https://doi.org/10.7717/peerj.10475" year="2021 a">Rollot et al. 2021a</bibRefCitation>
). BSPG 1991 II 130 has a morphology of the
<normalizedToken id="D614829B682E8C137A2AF3D8830B3E4E" originalValue="“cavernous”">&quot;cavernous&quot;</normalizedToken>
area that differs strongly from this generalized testudine bauplan. Our examination of comparative material shows that the morphology of BSPG 1991 II 130 is, however, also mirrored in
<taxonomicName id="45042E9D2DE1D74F768CA3165C0CF7BE" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="DA33CC4C6454E791B4CCE0589A2C43A4" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
, but the distinctness of this morphology has, to our knowledge, not been noticed or described before. In BSPG 1991 II 130, the most anterior aspect of the cavum acustico-jugulare does not become constricted to a broad canalis cavernosus as is the general condition in turtles. Instead, there is an anteriorly directed, large, circular opening that exits from the cavum acustico-jugulare directly into the vicinity of the mandibular artery foramen.
<bibRefCitation id="031EDC2195BA084CEA032450F777905F" DOI="https://doi.org/10.3374/014.055.0207" author="Havlik, PE" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="201 - 214" refId="B26" refString="Havlik, PE, Joyce, WG, Boehme, M, 2014. Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya. Bulletin of the Peabody Museum of Natural History 55 (2): 201 - 214, DOI: https://doi.org/10.3374/014.055.0207" title="Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya." url="https://doi.org/10.3374/014.055.0207" volume="55" year="2014">Havlik et al. (2014)</bibRefCitation>
identified this opening as the
<normalizedToken id="66435DC472BE24E35A70C840C0CFA4D9" originalValue="“posterior”">&quot;posterior&quot;</normalizedToken>
trigeminal nerve foramen. However, the opening cannot be directly associated with the trigeminal nerve, because it is connected to the cavum acustico-jugulare, and not the cavum cranii, which houses the brain from where the cranial nerves stem. Instead, the opening is likely associated with the mandibular artery, which in many turtle groups passes from the cavum acustico-jugulare into the canalis cavernosus, from where it has different courses it can take to reach the mandible. In many turtles, the mandibular artery passes laterally through the trigeminal foramen (
<bibRefCitation id="D4D3B5282DF97B7FD6CA216381E8082E" DOI="https://doi.org/10.1002/jmor.1051490203" author="Albrecht, PW" journalOrPublisher="Journal of Morphology" pageId="0" pageNumber="13" pagination="159 - 182" refId="B2" refString="Albrecht, PW, 1976. The cranial arteries of turtles and their evolutionary significance. Journal of Morphology 149 (2): 159 - 182, DOI: https://doi.org/10.1002/jmor.1051490203" title="The cranial arteries of turtles and their evolutionary significance." url="https://doi.org/10.1002/jmor.1051490203" volume="149" year="1976">Albrecht 1976</bibRefCitation>
), but it can also pass through the interorbital foramen as in
<taxonomicName id="858278E8AE1B3FD9D8EC94168AD7D16B" authorityName="Gray" authorityYear="1847" class="Reptilia" family="Dermatemydidae" genus="Dermatemys" higherTaxonomySource="GBIF" kingdom="Animalia" lsidName="Dermatemys mawii" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="mawii">
<emphasis id="3699D2D8F3CB43D2EFC627396CAF580A" italics="true" pageId="0" pageNumber="13">Dermatemys mawii</emphasis>
</taxonomicName>
(
<bibRefCitation id="AB6243DAC3DA637449536FC9B27BEA4A" DOI="https://doi.org/10.1038/s41467-022-33091-5" author="Evers, SW" journalOrPublisher="Zoological Journal of the Linnean Society" pageId="0" pageNumber="13" refId="B17" refString="Evers, SW, Joyce, WG, Choiniere, JN, Ferreira, GS, Foth, C, Hermanson, G, Yi, H, Johnson, CM, Werneburg, I, Benson, RBJ, 2022. Independent origin of large labyrinth size in turtles. Nature Communications 13: 5807. https://doi.org/10.1038/s41467-022-33091-5" title="Independent origin of large labyrinth size in turtles. Nature Communications 13: 5807." url="https://doi.org/10.1038/s41467-022-33091-5" year="2022">Evers et al. 2022</bibRefCitation>
), or it can pass through a separate foramen opening from the canalis cavernosus into the temporal fossa, as in some testudinids like gopher tortoises, but also as in
<taxonomicName id="BC5EF28F8DD01DD25A646E644D246532" baseAuthorityName="Linnaeus" baseAuthorityYear="1758" class="Reptilia" family="Cheloniidae" genus="Chelonia" higherTaxonomySource="GBIF" kingdom="Animalia" lsidName="Chelonia mydas" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="mydas">
<emphasis id="CC140656868073CBD0EDF158204E64F0" italics="true" pageId="0" pageNumber="13">Chelonia mydas</emphasis>
</taxonomicName>
(e.g.,
<bibRefCitation id="1481DBE9669F217647177FAB0C9004F5" author="McDowell, SB" journalOrPublisher="Bulletin of the Museum of Comparative Zoology" pageId="0" pageNumber="13" pagination="23 - 39" refId="B35" refString="McDowell, SB, 1961. On the major arterial canals in the ear region of testudinoid turtles and the classification of the Testudinoidea. Bulletin of the Museum of Comparative Zoology 125: 23 - 39" title="On the major arterial canals in the ear region of testudinoid turtles and the classification of the Testudinoidea." volume="125" year="1961">McDowell 1961</bibRefCitation>
;
<bibRefCitation id="216188BEBEBD3D24614952BFF1D7E012" DOI="https://doi.org/10.2307/1563715" author="Crumly, CR" journalOrPublisher="Journal of Herpetology" pageId="0" pageNumber="13" pagination="215 - 234" refId="B9" refString="Crumly, CR, 1982. A cladistic analysis of Geochelone using cranial osteology. Journal of Herpetology 16 (3): 215 - 234, DOI: https://doi.org/10.2307/1563715" title="A cladistic analysis of Geochelone using cranial osteology." url="https://doi.org/10.2307/1563715" volume="16" year="1982">Crumly 1982</bibRefCitation>
,
<bibRefCitation id="B3916B9C328FDD42E646C4A9A8AA27B1" author="Crumly, CR" journalOrPublisher="Fish and Wildlife Research" pageId="0" pageNumber="13" pagination="7 - 32" refId="B10" refString="Crumly, CR, 1994. Phylogenetic systematics of North American tortoises (genus Gopherus): Evidence for their classification. Fish and Wildlife Research 13: 7 - 32" title="Phylogenetic systematics of North American tortoises (genus Gopherus): Evidence for their classification." volume="13" year="1994">1994</bibRefCitation>
;
<bibRefCitation id="F976B9FE2E98A3646F344D582E040345" DOI="https://doi.org/10.1111/pala.12384" author="Evers, SW" journalOrPublisher="Palaeontology" pageId="0" pageNumber="13" pagination="93 - 134" refId="B15" refString="Evers, SW, Benson, RBJ, 2019. A new phylogenetic hypothesis of turtles with implications for the timing and number of evolutionary transitions to marine lifestyles in the group. Palaeontology 62 (1): 93 - 134, DOI: https://doi.org/10.1111/pala.12384" title="A new phylogenetic hypothesis of turtles with implications for the timing and number of evolutionary transitions to marine lifestyles in the group." url="https://doi.org/10.1111/pala.12384" volume="62" year="2019">Evers and Benson 2019</bibRefCitation>
;
<bibRefCitation id="9BA17015D2087932B282F5FC5BBD7929" DOI="https://doi.org/10.7717/peerj.10475" author="Rollot, Y" journalOrPublisher="BMC Evolutionary Biology" pageId="0" pageNumber="13" refId="B41" refString="Rollot, Y, Evers, SW, Joyce, WG, 2021a. A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e10475. https://doi.org/10.7717/peerj.10475" title="A review of the carotid artery and facial nerve canal systems in extant turtles. PeerJ 8: e 10475." url="https://doi.org/10.7717/peerj.10475" year="2021 a">Rollot et al. 2021a</bibRefCitation>
). In
<taxonomicName id="281899F0DFAFA6B0C156F84328A03A85" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="1826FADAF5E68DCBE1672B8304BBFE15" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
, there is no separate mandibular artery foramen, but the trigeminal foramen is posteroventrally elongated (Fig.
<figureCitation id="D51885CBD26094928DB83412BB7ED9A1" captionStart="Figure 3" captionStartId="F3" captionText="Figure 3. Three-dimensional renderings of the left trigeminal area of Allaeochelys libyca (BSPG 1991 II 113) and Carettochelys insculpta (NHMUK 1903.7.10.1). A. Left trigeminal area of Allaeochelys libyca in anterolateral view; B. Close-up on the left trigeminal area of Allaeochelys libyca; C. Left trigeminal area of Carettochelys insculpta in anterolateral view; D. Close-up on the left trigeminal area of Carettochelys insculpta; E. Left trigeminal area of Carettochelys insculpta in anterolateral view with the epipterygoid removed; F. Close-up on the left trigeminal area of Carettochelys insculpta with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in Carettochelys insculpta." figureDoi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13">3C, D</figureCitation>
). Instead of being a nearly circular or slightly oval foramen, the trigeminal opening is stretched and slightly curved. Hereby, the posteroventral aspect of the foramen essentially opens into the canalis cavernosus. This morphology suggests that the elongated trigeminal foramen of
<taxonomicName id="B5C9D406AC4797041B99B890C7C39390" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="80863B3E530D16C1B8C8143B203AEF3E" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
essentially incorporates a mandibular foramen. Herein, we call this morphology the &quot;trigeminal foramen
<emphasis id="CAACA8872617957993591FBA6EEA047A" italics="true" pageId="0" pageNumber="13">sensu lato</emphasis>
&quot;. The opening from the cavum acustico-jugulare of BSPG 1991 II 130 likely represents the posteroventral part of an incompletely preserved trigeminal foramen
<emphasis id="DCB0CE4099DA45BA537E5571D83A01AD" italics="true" pageId="0" pageNumber="13">sensu lato.</emphasis>
In BSPG 1991 II 130 and
<taxonomicName id="D9662E8EBDB18EE5305369620BD02B54" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="1FA1C4FB35466ECA560CE86FD302FA8B" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
, the trigeminal foramen
<emphasis id="113FB9FC33F1DD1F3A0AEF4B0D406947" italics="true" pageId="0" pageNumber="13">sensu lato</emphasis>
is formed largely by the quadrate and protic, with a ventral contribution of the pterygoid. Whereas in the incompletely preserved BSPG 1991 II 130 it looks like a canalis cavernosus is entirely reduced, the morphology of
<taxonomicName id="21EFBECD56AE93E3B76CCD53718B4E81" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="D0DB4E7E5847F47AB17AD2A1FA0D95CE" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
shows otherwise: in the extant form, the epipterygoid forms a bony bridge from the pterygoid region of the trigeminal foramen
<emphasis id="B9B094311C4B8E156BCF44964867898B" italics="true" pageId="0" pageNumber="13">sensu lato</emphasis>
to the descending process of the parietal (Fig.
<figureCitation id="180123D30015CA8F362F1656172617F3" captionStart="Figure 3" captionStartId="F3" captionText="Figure 3. Three-dimensional renderings of the left trigeminal area of Allaeochelys libyca (BSPG 1991 II 113) and Carettochelys insculpta (NHMUK 1903.7.10.1). A. Left trigeminal area of Allaeochelys libyca in anterolateral view; B. Close-up on the left trigeminal area of Allaeochelys libyca; C. Left trigeminal area of Carettochelys insculpta in anterolateral view; D. Close-up on the left trigeminal area of Carettochelys insculpta; E. Left trigeminal area of Carettochelys insculpta in anterolateral view with the epipterygoid removed; F. Close-up on the left trigeminal area of Carettochelys insculpta with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in Carettochelys insculpta." figureDoi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13">3C, D</figureCitation>
). Hereby, the epipterygoid forms the anterolateral wall of a tightly constricted space between the epipterygoid, pterygoid and prootic, which clearly corresponds to a strongly size-reduced canalis cavernosus. In BSPG 1991 II 130, the epipterygoid is not preserved, so that the impression of a complete absence of the canalis cavernosus is given. However, a small process of the prootic in the dorsal margin of the partly preserved trigeminal foramen
<emphasis id="4D62446E5E2E467448A656666990B365" italics="true" pageId="0" pageNumber="13">sensu lato</emphasis>
of BSPG 1991 II 30 (Fig.
<figureCitation id="3E142ADB6BA920EF9FEFBB9AD0099CB6" captionStart="Figure 3" captionStartId="F3" captionText="Figure 3. Three-dimensional renderings of the left trigeminal area of Allaeochelys libyca (BSPG 1991 II 113) and Carettochelys insculpta (NHMUK 1903.7.10.1). A. Left trigeminal area of Allaeochelys libyca in anterolateral view; B. Close-up on the left trigeminal area of Allaeochelys libyca; C. Left trigeminal area of Carettochelys insculpta in anterolateral view; D. Close-up on the left trigeminal area of Carettochelys insculpta; E. Left trigeminal area of Carettochelys insculpta in anterolateral view with the epipterygoid removed; F. Close-up on the left trigeminal area of Carettochelys insculpta with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in Carettochelys insculpta." figureDoi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13">3A, B</figureCitation>
) suggests that an epipterygoid with similar contacts and shape as in
<taxonomicName id="8B3A621EE000B8295059D123849176CA" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="709CDEF93C5316701D02E0374E8A89B2" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
(Fig.
<figureCitation id="A73D486593B708E4D8EA8F6CA79076E3" captionStart="Figure 3" captionStartId="F3" captionText="Figure 3. Three-dimensional renderings of the left trigeminal area of Allaeochelys libyca (BSPG 1991 II 113) and Carettochelys insculpta (NHMUK 1903.7.10.1). A. Left trigeminal area of Allaeochelys libyca in anterolateral view; B. Close-up on the left trigeminal area of Allaeochelys libyca; C. Left trigeminal area of Carettochelys insculpta in anterolateral view; D. Close-up on the left trigeminal area of Carettochelys insculpta; E. Left trigeminal area of Carettochelys insculpta in anterolateral view with the epipterygoid removed; F. Close-up on the left trigeminal area of Carettochelys insculpta with the epipterygoid removed. Abbreviations: aqf, anterior quadrate foramen; epi, epipterygoid; fam, foramen arteriomandibulare; fc, foramen cavernosum; fnt, foramen nervi trigemini; pal, palatine; pbs, parabasisphenoid; pro, prootic; pt, pterygoid; pto, processus trochlearis oticum; qu, quadrate. Black arrowheads indicate the anteroventral bump on the prootic that is interpreted as serving for the contact with the epipterygoid, and the white arrowhead indicates the lateral margin of the sulcus cavernosus formed by the pterygoid in Carettochelys insculpta." figureDoi="10.3897/fr.27.115046.figure3" httpUri="https://binary.pensoft.net/fig/961959" pageId="0" pageNumber="13">3C-F</figureCitation>
) was once present. Thus, the large, circular foramen of BSPG 1991 II 130 likely corresponds to the part of the trigeminal foramen
<emphasis id="834D9C5266465AA15DBC3AD7742F63CD" italics="true" pageId="0" pageNumber="13">sensu lato</emphasis>
through which the mandibular artery would pass into the temporal cavity, and the likely confluence with the trigeminal foramen is not evident due to the missing epipterygoid, which would have encased a size-reduced canalis cavernosus. An alternative interpretation of the region in BSPG 1991 II 130 would be that the sulcus cavernosus indeed is entirely reduced, and that the mandibular artery and lateral head vein both exit into the temporal fossa. If the morphology of
<taxonomicName id="10184611046BD31C7BED08C0E76657F3" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="804BBFA40A25E038040C098B1DC3B520" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
is informative about the plesiomorphic state of carettochelyid evolution, this scenario would require a complete loss of the canalis cavernosus in
<taxonomicName id="D1ED70F7B0A38F57C11A2AD9D14B0DED" authorityName="Noulet" authorityYear="1867" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys" order="Testudines" pageId="0" pageNumber="13" rank="genus">
<emphasis id="5B947B7435AC880FCD3F387E7B70B8FA" italics="true" pageId="0" pageNumber="13">Allaeochelys</emphasis>
</taxonomicName>
and then the re-evolution of a size-reduced canalis cavernosus in
<taxonomicName id="91361EE7AD09041503F029E804F4550C" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="E3C8BB4DB9CCFF7A7DA832011E9B5334" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
, which we think is less likely.
</paragraph>
<paragraph id="7C5EE2F02D7B2C48C031347308D445CB" pageId="0" pageNumber="13">
<emphasis id="8D65894405236028BB32826F9CF3B9D7" bold="true" pageId="0" pageNumber="13">Opisthotic.</emphasis>
The two opisthotics are damaged and lack their most anteromedial portion, which contributes to the hiatus acusticus, and most of the processus interfenestralis. The opisthotic contacts the prootic anteriorly, the supraoccipital medially, the quadrate laterally, the exoccipital posteroventromedially, and the pterygoid posteroventrolaterally (Fig.
<figureCitation id="C25726D5D78B8C73FE453CC20372B49D" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A, F</figureCitation>
). A small contact between the basioccipital and processus interfenestralis of the opisthotic might have been present, but is obscured by damage. The opisthotic forms the posterior half of the endosseous labyrinth, the lateral semicircular canal, and the posterior half of the posterior semicircular canal. The most lateral aspect of the left processus interfenestralis is preserved, which allows assessing that the opisthotic forms the posterior half of the fenestra ovalis and that the processus interfenestralis ventrally contacts the pterygoid. The amount of damage that affects the processus interfenestralis, however, prevents us to observe any other structure to which the process usually contributes in carettochelyids. We are therefore unable to provide any anatomical details about the fenestra perilymphatica or the foramina associated with the glossopharyngeal nerve course. The processus interfenestralis forms the anterior wall of the recessus scalae tympani, which is notably large in BSPG 1991 II 130. Posteriorly, the opisthotic forms the posterior wall to the recessus scalae tympani that ventrally contacts the pterygoid and forms the medial margin of the fenestra postotica (Fig.
<figureCitation id="8E43697E125823E472AFADD98FD0F82E" captionStart="Figure 5" captionStartId="F5" captionText="Figure 5. Three-dimensional renderings of the left posterior portion of BSPG 1991 II 113. A. Posterolateral view; B. Posteroventrolateral view; C. Anterodorsolateral view. Abbreviations: bo, basioccipital; ex, exoccipital; fenh, foramen externum nervi hypoglossi; finh, foramen internum nervi hypoglossi; fjp, foramen jugulare posterius; fpcci, foramen posterius canalis carotici interni; fpo, fenestra postotica; op, opisthotic; pt, pterygoid; qf, quadrate fossa; qu, quadrate; rst, recessus scalae tympani; so, supraoccipital. Black arrowhead indicates the position of the foramen oropharyngeale." figureDoi="10.3897/fr.27.115046.figure5" httpUri="https://binary.pensoft.net/fig/961961" pageId="0" pageNumber="13">5A</figureCitation>
). At the level of the suture with the pterygoid, the opisthotic forms alongside the latter bone a small canal that extends posterolaterally and joins the back of the cranium by means of a foramen formed by these two bones (Fig.
<figureCitation id="0DA97367BD883F1E9DB5763BEB787484" captionStart="Figure 5" captionStartId="F5" captionText="Figure 5. Three-dimensional renderings of the left posterior portion of BSPG 1991 II 113. A. Posterolateral view; B. Posteroventrolateral view; C. Anterodorsolateral view. Abbreviations: bo, basioccipital; ex, exoccipital; fenh, foramen externum nervi hypoglossi; finh, foramen internum nervi hypoglossi; fjp, foramen jugulare posterius; fpcci, foramen posterius canalis carotici interni; fpo, fenestra postotica; op, opisthotic; pt, pterygoid; qf, quadrate fossa; qu, quadrate; rst, recessus scalae tympani; so, supraoccipital. Black arrowhead indicates the position of the foramen oropharyngeale." figureDoi="10.3897/fr.27.115046.figure5" httpUri="https://binary.pensoft.net/fig/961961" pageId="0" pageNumber="13">5A</figureCitation>
). The canal and foramen may have served as a passage for the glossopharyngeal nerve, as the latter is known to extend posterolaterally within the recessus scalae tympani and through the fenestra postotica in turtles (
<bibRefCitation id="3A9E4BC211B894079333CDB0AF9FF765" author="Soliman, MA" journalOrPublisher="Zeitschrift fuer Wissenschaftliche Zoologie" pageId="0" pageNumber="13" pagination="216 - 312" refId="B44" refString="Soliman, MA, 1964. Die Kopfnerven der Schildkroeten. Zeitschrift fuer Wissenschaftliche Zoologie 169: 216 - 312" title="Die Kopfnerven der Schildkroeten." volume="169" year="1964">Soliman 1964</bibRefCitation>
;
<bibRefCitation id="4BA011BF31D43F01B290F0C6924BA94D" author="Gaffney, ES" journalOrPublisher="Bulletin of the American Museum of Natural History" pageId="0" pageNumber="13" pagination="65 - 376" refId="B22" refString="Gaffney, ES, 1979. Comparative cranial morphology of recent and fossil turtles. Bulletin of the American Museum of Natural History 164: 65 - 376" title="Comparative cranial morphology of recent and fossil turtles." volume="164" year="1979">Gaffney 1979</bibRefCitation>
).
</paragraph>
<caption id="FAB242841BF5F974C5AE229681BB3F88" doi="10.3897/fr.27.115046.figure5" httpUri="https://binary.pensoft.net/fig/961961" pageId="0" pageNumber="13" start="Figure 5" startId="F5">
<paragraph id="3CFB234B82C6BA1227EA2BEC78410C1A" pageId="0" pageNumber="13">
<emphasis id="9F2F85E693AA68356CE2863A342D06CB" bold="true" pageId="0" pageNumber="13">Figure 5.</emphasis>
Three-dimensional renderings of the left posterior portion of BSPG 1991 II 113.
<emphasis id="C13B88A5FAA96ACEE4E06E02377769CE" bold="true" pageId="0" pageNumber="13">A.</emphasis>
Posterolateral view;
<emphasis id="DA0CE1B6329120D3B54BE584B948D3D9" bold="true" pageId="0" pageNumber="13">B.</emphasis>
Posteroventrolateral view;
<emphasis id="62566170EAD25A3F4F7615F56D8F40BE" bold="true" pageId="0" pageNumber="13">C.</emphasis>
Anterodorsolateral view. Abbreviations: bo, basioccipital; ex, exoccipital; fenh, foramen externum nervi hypoglossi; finh, foramen internum nervi hypoglossi; fjp, foramen jugulare posterius; fpcci, foramen posterius canalis carotici interni; fpo, fenestra postotica; op, opisthotic; pt, pterygoid; qf, quadrate fossa; qu, quadrate; rst, recessus scalae tympani; so, supraoccipital. Black arrowhead indicates the position of the foramen oropharyngeale.
</paragraph>
</caption>
<paragraph id="63B2F6D8785317E99690A2874F4560BA" pageId="0" pageNumber="13">
<emphasis id="E1DB66F66C157A1DA0366DF5B8EC9AAF" bold="true" pageId="0" pageNumber="13">Supraoccipital.</emphasis>
The supraoccipital is incomplete, lacking its most anterior and anterodorsal parts and the crista supraoccipitalis almost completely. The supraoccipital contacts the parietal anteriorly, the prootic anterolaterally, the opisthotic posterolaterally, and the exoccipital posteroventrolaterally (Fig.
<figureCitation id="AD7A31CC455DB37E595F048028847B6A" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A, F</figureCitation>
). The supraoccipital forms the posterior half of the braincase roof, the posterior half of the anterior semicircular canal, the anterior half of the posterior semicircular canal, the dorsal margin of the hiatus acusticus, and the dorsal margin of the foramen magnum. Although the crista supraoccipitalis is broken off, a small portion of the mediolaterally expanded plate usually seen in carettochelyids is preserved (Fig.
<figureCitation id="E88919C7DC4A719F95AC52B706DA7014" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A</figureCitation>
). The expanded plate starts posterior to the level of the prootic-opisthotic contact, just medial to the contact between the supraoccipital and opisthotic. In dorsal view, it is apparent that the lateral margins of the preserved portion of the expanded plate are slightly concave, and seem to slightly broaden again towards the posterior (Fig.
<figureCitation id="C294C3C129D92FF5F18F26F21678A104" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1A</figureCitation>
), suggesting that the expanded plate of the crista supraoccipitalis was broader posteriorly, as in
<taxonomicName id="F83B95A8F2224D5CFDEA137B6291F096" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="B94ACEFFE2A91514D9E6384DC28B6191" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
(
<bibRefCitation id="47317685D71090DD827BDF1AA6D15CE9" DOI="https://doi.org/10.3374/014.055.0102" author="Joyce, WG" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="3 - 33" refId="B28" refString="Joyce, WG, 2014. A review of the fossil record of turtles of the clade Pan-Carettochelys. Bulletin of the Peabody Museum of Natural History 55 (1): 3 - 33, DOI: https://doi.org/10.3374/014.055.0102" title="A review of the fossil record of turtles of the clade Pan-Carettochelys." url="https://doi.org/10.3374/014.055.0102" volume="55" year="2014">Joyce 2014</bibRefCitation>
), but not
<taxonomicName id="308518ED97C09B642572EEE5114EE3C3" baseAuthorityName="Clark" baseAuthorityYear="1932" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira pulchra" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="pulchra">
<emphasis id="F1390A4B5CFFB40EC303C7522FFF49F6" italics="true" pageId="0" pageNumber="13">Anosteira pulchra</emphasis>
</taxonomicName>
(
<bibRefCitation id="6B558275C2077EFCC33E0D924B3E7B01" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
).
</paragraph>
<paragraph id="E5081912654B2ACE0900B14016BB2ABE" pageId="0" pageNumber="13">
<emphasis id="72A5D13DF38E27AAE742A6890E1DC39C" bold="true" pageId="0" pageNumber="13">Basioccipital.</emphasis>
The basioccipital is almost complete, only lacking a small portion around the occipital condyle. The basioccipital can generally be differentiated in the CT scans from the exoccipitals, although the suture between the basioccipital and right exoccipital fades away slightly within the right tuberculum basioccipitale. The basioccipital contacts the parabasisphenoid anteriorly, the pterygoid laterally, and the exoccipital posterodorsolaterally and posterodorsally (Figs
<figureCitation id="6FD9DB0E58E806B95ED56AB15583D0C7" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B, F</figureCitation>
,
<figureCitation id="A46AD6847117FBBA90C6DFFB0797D510" captionStart="Figure 5" captionStartId="F5" captionText="Figure 5. Three-dimensional renderings of the left posterior portion of BSPG 1991 II 113. A. Posterolateral view; B. Posteroventrolateral view; C. Anterodorsolateral view. Abbreviations: bo, basioccipital; ex, exoccipital; fenh, foramen externum nervi hypoglossi; finh, foramen internum nervi hypoglossi; fjp, foramen jugulare posterius; fpcci, foramen posterius canalis carotici interni; fpo, fenestra postotica; op, opisthotic; pt, pterygoid; qf, quadrate fossa; qu, quadrate; rst, recessus scalae tympani; so, supraoccipital. Black arrowhead indicates the position of the foramen oropharyngeale." figureDoi="10.3897/fr.27.115046.figure5" httpUri="https://binary.pensoft.net/fig/961961" pageId="0" pageNumber="13">5</figureCitation>
). The contact of the basioccipital with the parabasisphenoid is mediolaterally elongate in ventral view, but is actually restricted to the most central aspect of the two bones more dorsally. This creates a depression lateral to the basioccipital-parabasisphenoid contact that expands the endosseous labyrinth ventrally. A crista basis tubercula basalis is likely absent, although this may be the result of the light damage that affects the anterodorsal surface of the basioccipital (Fig.
<figureCitation id="2F16B27D33B35D2D82BA2F52978EE8B2" captionStart="Figure 5" captionStartId="F5" captionText="Figure 5. Three-dimensional renderings of the left posterior portion of BSPG 1991 II 113. A. Posterolateral view; B. Posteroventrolateral view; C. Anterodorsolateral view. Abbreviations: bo, basioccipital; ex, exoccipital; fenh, foramen externum nervi hypoglossi; finh, foramen internum nervi hypoglossi; fjp, foramen jugulare posterius; fpcci, foramen posterius canalis carotici interni; fpo, fenestra postotica; op, opisthotic; pt, pterygoid; qf, quadrate fossa; qu, quadrate; rst, recessus scalae tympani; so, supraoccipital. Black arrowhead indicates the position of the foramen oropharyngeale." figureDoi="10.3897/fr.27.115046.figure5" httpUri="https://binary.pensoft.net/fig/961961" pageId="0" pageNumber="13">5C</figureCitation>
). In ventral view, the central part of the basioccipital forms a shallow depression that laterally reaches the tubercula basioccipitale, and posteriorly extends up to the occipital condyle (Fig.
<figureCitation id="9E672FE270EF9370EE401A2C1FE4A624" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B</figureCitation>
). The tubercula basioccipitale are posteriorly elongate (Figs
<figureCitation id="28073C5ED84A0AC651AF8BA25A3C0E89" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B</figureCitation>
,
<figureCitation id="BD4BA9481AA98F78EB845CF85916D572" captionStart="Figure 5" captionStartId="F5" captionText="Figure 5. Three-dimensional renderings of the left posterior portion of BSPG 1991 II 113. A. Posterolateral view; B. Posteroventrolateral view; C. Anterodorsolateral view. Abbreviations: bo, basioccipital; ex, exoccipital; fenh, foramen externum nervi hypoglossi; finh, foramen internum nervi hypoglossi; fjp, foramen jugulare posterius; fpcci, foramen posterius canalis carotici interni; fpo, fenestra postotica; op, opisthotic; pt, pterygoid; qf, quadrate fossa; qu, quadrate; rst, recessus scalae tympani; so, supraoccipital. Black arrowhead indicates the position of the foramen oropharyngeale." figureDoi="10.3897/fr.27.115046.figure5" httpUri="https://binary.pensoft.net/fig/961961" pageId="0" pageNumber="13">5</figureCitation>
), as in
<taxonomicName id="88B33A91BEEF17C465902F5B25A6730F" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="11FFFC85D9C57665C34BCF09C050F30D" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
(
<bibRefCitation id="CABAEE8DC3D8A27C2FEF219A63AD4804" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
;
<bibRefCitation id="748857D48329CC512EE64F521AB1DB52" DOI="https://doi.org/10.3374/014.055.0102" author="Joyce, WG" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="3 - 33" refId="B28" refString="Joyce, WG, 2014. A review of the fossil record of turtles of the clade Pan-Carettochelys. Bulletin of the Peabody Museum of Natural History 55 (1): 3 - 33, DOI: https://doi.org/10.3374/014.055.0102" title="A review of the fossil record of turtles of the clade Pan-Carettochelys." url="https://doi.org/10.3374/014.055.0102" volume="55" year="2014">Joyce 2014</bibRefCitation>
) and
<taxonomicName id="EFB05A940623BA2100C3FD7B86548942" baseAuthorityName="Harrassowitz" baseAuthorityYear="1922" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys crassesculpta" order="Testudines" pageId="0" pageNumber="13" rank="species" species="crassesculpta">
<emphasis id="D52E0EFB324E1DFDB1B4DAA1EB98ED16" italics="true" pageId="0" pageNumber="13">Allaeochelys crassesculpta</emphasis>
</taxonomicName>
(
<bibRefCitation id="EA32BEA436DAF7BF8E0E7E53F9F9D378" author="Harrassowitz, H" journalOrPublisher="Abhandlungen der Hessischen Geologischen Landesanstalt" pageId="0" pageNumber="13" pagination="132 - 239" refId="B25" refString="Harrassowitz, H, 1922. Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung. Abhandlungen der Hessischen Geologischen Landesanstalt 6: 132 - 239" title="Die Schildkroetengattung Anosteira von Messel bei Darmstadt und ihre stammesgeschichtliche Bedeutung." volume="6" year="1922">Harrassowitz 1922</bibRefCitation>
), but different from the short processes seen in
<taxonomicName id="CC3E7E043C7EC123C06FAFF9A99DBF24" baseAuthorityName="Clark" baseAuthorityYear="1932" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira pulchra" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="pulchra">
<emphasis id="2FD1E4AEAD66D420A4F7B77003958752" italics="true" pageId="0" pageNumber="13">Anosteira pulchra</emphasis>
</taxonomicName>
(
<bibRefCitation id="2BFEC155EA823916A50C5CC70FE6780A" DOI="https://doi.org/10.5194/fr-21-301-2018" author="Joyce, WG" journalOrPublisher="Fossil Record" pageId="0" pageNumber="13" pagination="301 - 310" refId="B29" refString="Joyce, WG, Volpato, VS, Rollot, Y, 2018. The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles. Fossil Record 21 (2): 301 - 310, DOI: https://doi.org/10.5194/fr-21-301-2018" title="The skull of the carettochelyid turtle Anosteira pulchra from the Eocene (Uintan) of Wyoming and the carotid canal system of carettochelyid turtles." url="https://doi.org/10.5194/fr-21-301-2018" volume="21" year="2018">Joyce et al. 2018</bibRefCitation>
). The occipital condyle is greatly damaged and only the base of the exoccipital lobes is preserved (Figs
<figureCitation id="A67D6465341139788FFE55343CDA6426" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1F</figureCitation>
,
<figureCitation id="20DD3462D59EA88AE387D115378DEAB1" captionStart="Figure 5" captionStartId="F5" captionText="Figure 5. Three-dimensional renderings of the left posterior portion of BSPG 1991 II 113. A. Posterolateral view; B. Posteroventrolateral view; C. Anterodorsolateral view. Abbreviations: bo, basioccipital; ex, exoccipital; fenh, foramen externum nervi hypoglossi; finh, foramen internum nervi hypoglossi; fjp, foramen jugulare posterius; fpcci, foramen posterius canalis carotici interni; fpo, fenestra postotica; op, opisthotic; pt, pterygoid; qf, quadrate fossa; qu, quadrate; rst, recessus scalae tympani; so, supraoccipital. Black arrowhead indicates the position of the foramen oropharyngeale." figureDoi="10.3897/fr.27.115046.figure5" httpUri="https://binary.pensoft.net/fig/961961" pageId="0" pageNumber="13">5A, B</figureCitation>
). The preserved portion neither allows to determine with confidence to which extent each bone contributed to the condyle, nor how many lobes were actually forming the condyle. Although the basioccipital is exposed ventromedially between the exoccipitals, a slight reduction in width of the basioccipital towards the posterior is apparent in the
<normalizedToken id="98A4CC06D9DA0318274CFDB55252B556" originalValue="µCT">µCT</normalizedToken>
image stack, but our observations are not sufficient to determine with confidence the morphology of the occipital condyle in BSPG 1991 II 130.
</paragraph>
<paragraph id="CB47ADBC832053ADC306CC42D40FE278" pageId="0" pageNumber="13">
<emphasis id="970C6F67E44390631C99A1627D694DFA" bold="true" pageId="0" pageNumber="13">Exoccipital.</emphasis>
The exoccipitals are almost complete, only the portion around the occipital condyle is damaged. The exoccipital contacts the supraoccipital dorsally, the opisthotic laterally, the pterygoid ventrolaterally, and the basioccipital ventrally (Figs
<figureCitation id="76FE0DDC64CA1E89B4CAE895DD69B905" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1F</figureCitation>
,
<figureCitation id="F6E333BB5A365878C95A96CBD0D6C33F" captionStart="Figure 5" captionStartId="F5" captionText="Figure 5. Three-dimensional renderings of the left posterior portion of BSPG 1991 II 113. A. Posterolateral view; B. Posteroventrolateral view; C. Anterodorsolateral view. Abbreviations: bo, basioccipital; ex, exoccipital; fenh, foramen externum nervi hypoglossi; finh, foramen internum nervi hypoglossi; fjp, foramen jugulare posterius; fpcci, foramen posterius canalis carotici interni; fpo, fenestra postotica; op, opisthotic; pt, pterygoid; qf, quadrate fossa; qu, quadrate; rst, recessus scalae tympani; so, supraoccipital. Black arrowhead indicates the position of the foramen oropharyngeale." figureDoi="10.3897/fr.27.115046.figure5" httpUri="https://binary.pensoft.net/fig/961961" pageId="0" pageNumber="13">5</figureCitation>
). The exoccipital forms the posterolateral wall of the braincase and the lateral margin of the foramen magnum. Within the braincase, the exoccipital forms two internal foramina for the hypoglossal nerve (Fig.
<figureCitation id="10A301691E003305D7D3CAB6AA7A4E3B" captionStart="Figure 5" captionStartId="F5" captionText="Figure 5. Three-dimensional renderings of the left posterior portion of BSPG 1991 II 113. A. Posterolateral view; B. Posteroventrolateral view; C. Anterodorsolateral view. Abbreviations: bo, basioccipital; ex, exoccipital; fenh, foramen externum nervi hypoglossi; finh, foramen internum nervi hypoglossi; fjp, foramen jugulare posterius; fpcci, foramen posterius canalis carotici interni; fpo, fenestra postotica; op, opisthotic; pt, pterygoid; qf, quadrate fossa; qu, quadrate; rst, recessus scalae tympani; so, supraoccipital. Black arrowhead indicates the position of the foramen oropharyngeale." figureDoi="10.3897/fr.27.115046.figure5" httpUri="https://binary.pensoft.net/fig/961961" pageId="0" pageNumber="13">5C</figureCitation>
). The more anterior foramen is smaller and located just above the suture between the exoccipital and basioccipital. The other foramen is larger and located more posteriorly, at the level of the foramen magnum. Both foramina lead into separate canalis nervi hypoglossi that extend posterolaterally through the exoccipital. The exterior foramina nervi hypoglossi are separate but close to one another, located in a shallow cavity that lies lateral to the occipital condyle and just dorsal to the exoccipital-basioccipital suture (Fig.
<figureCitation id="B3D7AE5293FF227D46BB99A5E3B14CE1" captionStart="Figure 5" captionStartId="F5" captionText="Figure 5. Three-dimensional renderings of the left posterior portion of BSPG 1991 II 113. A. Posterolateral view; B. Posteroventrolateral view; C. Anterodorsolateral view. Abbreviations: bo, basioccipital; ex, exoccipital; fenh, foramen externum nervi hypoglossi; finh, foramen internum nervi hypoglossi; fjp, foramen jugulare posterius; fpcci, foramen posterius canalis carotici interni; fpo, fenestra postotica; op, opisthotic; pt, pterygoid; qf, quadrate fossa; qu, quadrate; rst, recessus scalae tympani; so, supraoccipital. Black arrowhead indicates the position of the foramen oropharyngeale." figureDoi="10.3897/fr.27.115046.figure5" httpUri="https://binary.pensoft.net/fig/961961" pageId="0" pageNumber="13">5A, B</figureCitation>
). Our interpretation differs from that of
<bibRefCitation id="8ACB679434BFB510EA967BAEBD776124" DOI="https://doi.org/10.3374/014.055.0207" author="Havlik, PE" journalOrPublisher="Bulletin of the Peabody Museum of Natural History" pageId="0" pageNumber="13" pagination="201 - 214" refId="B26" refString="Havlik, PE, Joyce, WG, Boehme, M, 2014. Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya. Bulletin of the Peabody Museum of Natural History 55 (2): 201 - 214, DOI: https://doi.org/10.3374/014.055.0207" title="Allaeochelys libyca, a new carettochelyine turtle from the Middle Miocene (Langhian) of Libya." url="https://doi.org/10.3374/014.055.0207" volume="55" year="2014">Havlik et al. (2014)</bibRefCitation>
, who identified three external foramina for the hypoglossal nerve. Cross-examination of the
<normalizedToken id="C37003C13B4C1CD47E7DD4FB40B6EABD" originalValue="µCT">µCT</normalizedToken>
scans available to us reveals that the most ventral of the three foramina identified by the latter authors actually corresponds to some porosity that is externally exposed, and that only two sets of internal and external foramina are present in
<taxonomicName id="DEF71867CB18BABF8EC4EEEB0418B5F7" family="Carettochelyidae" genus="Allaeochelys" kingdom="Animalia" lsidName="Allaeochelys libyca" order="Testudines" pageId="0" pageNumber="13" rank="species" species="libyca">
<emphasis id="262D493B1BED9654A206ABF3011C4C63" italics="true" pageId="0" pageNumber="13">Allaeochelys libyca</emphasis>
</taxonomicName>
, as in
<taxonomicName id="3C603459CDC2BE346BFD5A4028089176" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="8495AD74835CE9873667D1D12173979F" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
(
<bibRefCitation id="7660E886150FABFACE978841A3A4469B" DOI="https://doi.org/10.5962/bhl.title.11842" author="Walther, WG" journalOrPublisher="Nova Guinea" pageId="0" pageNumber="13" pagination="607 - 704" refId="B53" refString="Walther, WG, 1922. Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay. Nova Guinea 13: 607 - 704, DOI: https://doi.org/10.5962/bhl.title.11842" title="Die Neu-Guinea-Schildkroete Carettochelys insculpta Ramsay." url="https://doi.org/10.5962/bhl.title.11842" volume="13" year="1922">Walther 1922</bibRefCitation>
) and
<taxonomicName id="43CDBAD181802E08D7A8303CE98A5F24" baseAuthorityName="Clark" baseAuthorityYear="1932" class="Testudines" family="Carettochelyidae" genus="Anosteira" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Anosteira pulchra" order="Cryptodira" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="pulchra">
<emphasis id="B1F1A790264D49BF576C1134DA5C24D6" italics="true" pageId="0" pageNumber="13">Anosteira pulchra</emphasis>
</taxonomicName>
(FMNH PR966). The anteromedial surface of the exoccipital is concave and smooth and forms parts of the posterior wall of the recessus scalae tympani. Within the recessus scalae tympani, the exoccipital forms a moderately large but short canal that extends posterolaterally and joins the posterior surface of the exoccipital by means of the foramen jugulare posterius, which is located just dorsolateral to the foramina externum nervi hypoglossi (Fig.
<figureCitation id="E77272A708864AE4F2B1989B69CE414B" captionStart="Figure 5" captionStartId="F5" captionText="Figure 5. Three-dimensional renderings of the left posterior portion of BSPG 1991 II 113. A. Posterolateral view; B. Posteroventrolateral view; C. Anterodorsolateral view. Abbreviations: bo, basioccipital; ex, exoccipital; fenh, foramen externum nervi hypoglossi; finh, foramen internum nervi hypoglossi; fjp, foramen jugulare posterius; fpcci, foramen posterius canalis carotici interni; fpo, fenestra postotica; op, opisthotic; pt, pterygoid; qf, quadrate fossa; qu, quadrate; rst, recessus scalae tympani; so, supraoccipital. Black arrowhead indicates the position of the foramen oropharyngeale." figureDoi="10.3897/fr.27.115046.figure5" httpUri="https://binary.pensoft.net/fig/961961" pageId="0" pageNumber="13">5</figureCitation>
). Medially, the exoccipital forms the posterior margin of the foramen jugulare anterius, i.e., the internal opening between the recessus scalae tympani and the braincase. The exoccipital also forms the dorsal part of the elongate tubercula basioccipitale with an elongated posterolateral process (Figs
<figureCitation id="86ED1E8763B5C8FB32ABD845EBC5AC16" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1F</figureCitation>
,
<figureCitation id="B70CDB86BB964EA9A723F28E334EFE2B" captionStart="Figure 5" captionStartId="F5" captionText="Figure 5. Three-dimensional renderings of the left posterior portion of BSPG 1991 II 113. A. Posterolateral view; B. Posteroventrolateral view; C. Anterodorsolateral view. Abbreviations: bo, basioccipital; ex, exoccipital; fenh, foramen externum nervi hypoglossi; finh, foramen internum nervi hypoglossi; fjp, foramen jugulare posterius; fpcci, foramen posterius canalis carotici interni; fpo, fenestra postotica; op, opisthotic; pt, pterygoid; qf, quadrate fossa; qu, quadrate; rst, recessus scalae tympani; so, supraoccipital. Black arrowhead indicates the position of the foramen oropharyngeale." figureDoi="10.3897/fr.27.115046.figure5" httpUri="https://binary.pensoft.net/fig/961961" pageId="0" pageNumber="13">5</figureCitation>
).
</paragraph>
<paragraph id="6757D0B05C26FD30B5C6F40A19CACD62" pageId="0" pageNumber="13">
<emphasis id="4821B71F0352957C8800B7DB7E6F32EE" bold="true" pageId="0" pageNumber="13">Parabasisphenoid.</emphasis>
The parabasisphenoid is broken at the anterior limit of the sella turcica. The anterior parts of the otherwise broad and flat rostrum basisphenoidale are therefore missing. The area around the clinoid process and retractor bulbi pits is damaged as well and we are not able to describe these structures. The parabasisphenoid contacts the palatine anteriorly, the pterygoid laterally, the prootic anterodorsolaterally, and the basioccipital posteriorly (Fig.
<figureCitation id="FABE5A83C92902B6FF86927C1C7F19A1" captionStart="Figure 1" captionStartId="F1" captionText="Figure 1. Three-dimensional renderings of the segmented cranium of BSPG 1991 II 113. A. Dorsal view; B. Ventral view; C. Left lateral view; D. Right lateral view; E. Anterior view; F. Posterior view. Abbreviations: aqf, anterior quadrate foramen; bo, basioccipital; ex, exoccipital; fr, frontal; op, opisthotic; pa, parietal; pbs, parabasisphenoid; pf, prefrontal; po, postorbital; pro, prootic; pt, pterygoid; ptf, pterygoid fossa; qu, quadrate; so, supraoccipital. Black arrowhead indicates the small, preserved portion of the right palatine. Dashed lines indicate the foramen stapedio-temporale in A, the passage between the orbit and nasal cavity in B, and the mandibular artery foramen in E." figureDoi="10.3897/fr.27.115046.figure1" httpUri="https://binary.pensoft.net/fig/961957" pageId="0" pageNumber="13">1B, E</figureCitation>
). The dorsal surface of the parabasisphenoid is concave and floors the braincase. The parabasisphenoid posteriorly forms a short, thin sheet of bone that underlies the basioccipital and gives the impression of a broad contact between the two bones, but the contact is dorsally limited to the most central portion of both the parabasisphenoid and basioccipital. The parabasisphenoid forms the dorsum sellae, which anteriorly projects to cover the sella turcica. The foramina anterius canalis carotici basisphenoidalis are located within the lateral corners of the sella turcica and lead into the canalis caroticus basisphenoidalis, which in BSPG 1991 II 130 are the anterior continuation of the canalis caroticus internus (Fig.
<figureCitation id="BBC51AA6FCF81D11E5D00FE5E95D41CE" captionStart="Figure 2" captionStartId="F2" captionText="Figure 2. Three-dimensional renderings of the circulatory system of BSPG 1991 II 113. A. Dorsal view; B. Dorsal view with bones rendered transparent. Abbreviations: af-op, articulation facet for the opisthotic; ccb, canalis caroticus basisphenoidalis; cci, canalis caroticus internus; cnf, canalis nervus facialis; cprnv, canalis pro ramo nervi vidiani; faccb, foramen anterius canalis carotici basisphenoidalis; fpcci, foramen posterius canalis carotici interni; fpcna, foramen posterius canalis nervi abducentis; pbs, parabasisphenoid; pt, pterygoid; stag, stapedial artery groove." figureDoi="10.3897/fr.27.115046.figure2" httpUri="https://binary.pensoft.net/fig/961958" pageId="0" pageNumber="13">2B</figureCitation>
). The foramina posterius canalis nervi abducentis are located along the dorsal surface of the parabasisphenoid, posterolateral to the dorsum sellae (Fig.
<figureCitation id="9DB8340CAC49E9714EDE92D6AEC0A00D" captionStart="Figure 2" captionStartId="F2" captionText="Figure 2. Three-dimensional renderings of the circulatory system of BSPG 1991 II 113. A. Dorsal view; B. Dorsal view with bones rendered transparent. Abbreviations: af-op, articulation facet for the opisthotic; ccb, canalis caroticus basisphenoidalis; cci, canalis caroticus internus; cnf, canalis nervus facialis; cprnv, canalis pro ramo nervi vidiani; faccb, foramen anterius canalis carotici basisphenoidalis; fpcci, foramen posterius canalis carotici interni; fpcna, foramen posterius canalis nervi abducentis; pbs, parabasisphenoid; pt, pterygoid; stag, stapedial artery groove." figureDoi="10.3897/fr.27.115046.figure2" httpUri="https://binary.pensoft.net/fig/961958" pageId="0" pageNumber="13">2A</figureCitation>
). The foramen posterius canalis nervi abducentis leads into the canalis nervus abducentis, which extends anteriorly through the parabasisphenoid. The anterior path of the canal and bony contributions to the foramen anterius canalis nervi abducentis remain unknown as this area is damaged in BSPG 1991 II 130.
</paragraph>
<paragraph id="307A7EF65939C5DC11FEE026295D5B84" pageId="0" pageNumber="13">
<emphasis id="C06B2579FD9645DB2D56466BD0D9F75E" bold="true" pageId="0" pageNumber="13">Endosseous labyrinth.</emphasis>
The semicircular canals are thick, with the anterior semicircular canal being the longest of the three and that anteriorly joins the vestibule at the level of the anterior ampulla (Fig.
<figureCitation id="2E1C8A72D8ACFD38E3771F6C91DA2295" captionStart="Figure 6" captionStartId="F6" captionText="Figure 6. Three-dimensional renderings of the left endosseous labyrinth of BSPG 1991 II 113. A. Lateral view; B. Posterior view; C. Dorsal view. Abbreviations: asc, anterior semicircular canal; cc, common crus; fov, fenestra ovalis; lam, lateral ampulla; lsc, lateral semicircular canal; psc, posterior semicircular canal; scc, secondary common crus." figureDoi="10.3897/fr.27.115046.figure6" httpUri="https://binary.pensoft.net/fig/961962" pageId="0" pageNumber="13">6</figureCitation>
). The posterior semicircular canal is shorter than the anterior canal and its posterior third is ventrally confluent with the posterior portion of the lateral semicircular canal, forming a large secondary common crus (Fig.
<figureCitation id="BDE93C7FADD41AC4643ADE092F74404E" captionStart="Figure 6" captionStartId="F6" captionText="Figure 6. Three-dimensional renderings of the left endosseous labyrinth of BSPG 1991 II 113. A. Lateral view; B. Posterior view; C. Dorsal view. Abbreviations: asc, anterior semicircular canal; cc, common crus; fov, fenestra ovalis; lam, lateral ampulla; lsc, lateral semicircular canal; psc, posterior semicircular canal; scc, secondary common crus." figureDoi="10.3897/fr.27.115046.figure6" httpUri="https://binary.pensoft.net/fig/961962" pageId="0" pageNumber="13">6B</figureCitation>
). The common crus is low and dorsally forms an embayment between the anterior and posterior semicircular canals, as in many other turtles (Fig.
<figureCitation id="24F159420A008004DCA8B8B1B572FA4D" captionStart="Figure 6" captionStartId="F6" captionText="Figure 6. Three-dimensional renderings of the left endosseous labyrinth of BSPG 1991 II 113. A. Lateral view; B. Posterior view; C. Dorsal view. Abbreviations: asc, anterior semicircular canal; cc, common crus; fov, fenestra ovalis; lam, lateral ampulla; lsc, lateral semicircular canal; psc, posterior semicircular canal; scc, secondary common crus." figureDoi="10.3897/fr.27.115046.figure6" httpUri="https://binary.pensoft.net/fig/961962" pageId="0" pageNumber="13">6A</figureCitation>
; see
<bibRefCitation id="873536A3DEF9F608DBAE457B61081655" DOI="https://doi.org/10.1093/zoolinnean/zlz063" author="Evers, SW" journalOrPublisher="Zoological Journal of the Linnean Society" pageId="0" pageNumber="13" pagination="800 - 828" refId="B16" refString="Evers, SW, Neenan, JM, Ferreira, GS, Werneburg, I, Barrett, PM, Benson, RB, 2019. Neurovascular anatomy of the protostegid turtle Rhinochelys pulchriceps and comparisons of membranous and endosseous labyrinth shape in an extant turtle. Zoological Journal of the Linnean Society 187 (3): 800 - 828, DOI: https://doi.org/10.1093/zoolinnean/zlz063" title="Neurovascular anatomy of the protostegid turtle Rhinochelys pulchriceps and comparisons of membranous and endosseous labyrinth shape in an extant turtle." url="https://doi.org/10.1093/zoolinnean/zlz063" volume="187" year="2019">Evers et al. 2019</bibRefCitation>
;
<bibRefCitation id="10DE80D542FB3AB113E50A80AA0D5677" DOI="https://doi.org/10.3390/d13070298" author="Martin-Jimenez, M" journalOrPublisher="Diversity" pageId="0" pageNumber="13" pagination=": 298" refId="B31" refString="Martin-Jimenez, M, Perez-Garcia, A, 2021. Neuroanatomical study and three-dimensional reconstruction of the skull of a bothremydid turtle (Pleurodira) based on the European Eocene Tartaruscola teodorii. Diversity 13 (7): 298, DOI: https://doi.org/10.3390/d13070298" title="Neuroanatomical study and three-dimensional reconstruction of the skull of a bothremydid turtle (Pleurodira) based on the European Eocene Tartaruscola teodorii." url="https://doi.org/10.3390/d13070298" volume="13" year="2021">
<normalizedToken id="D7E74FB7939B2CBEB625F7C619CAA268" originalValue="Martín-Jiménez">Martin-Jimenez</normalizedToken>
and
<normalizedToken id="2288AC7D186AD75773B67BD9F0197844" originalValue="Pérez-García">Perez-Garcia</normalizedToken>
2021
</bibRefCitation>
,
<bibRefCitation id="52E73D476BE5E539A4A51A17A2CE6399" DOI="https://doi.org/10.1002/ar.25072" author="Martin-Jimenez, M" journalOrPublisher="The Anatomical Record" pageId="0" pageNumber="13" pagination="1377 - 1395" refId="B32" refString="Martin-Jimenez, M, Perez-Garcia, A, 2022. The neuroanatomy of the bothremydid pleurodiran turtle Galianemys, from the Late Cretaceous (Cenomanian) of Morocco. The Anatomical Record 306 (6): 1377 - 1395, DOI: https://doi.org/10.1002/ar.25072" title="The neuroanatomy of the bothremydid pleurodiran turtle Galianemys, from the Late Cretaceous (Cenomanian) of Morocco." url="https://doi.org/10.1002/ar.25072" volume="306" year="2022">2022</bibRefCitation>
,
<bibRefCitation id="91BB4BCA0D348BC53F324FF3B8F5A0C6" DOI="https://doi.org/10.3390/d15030374" author="Martin-Jimenez, M" journalOrPublisher="Diversity" pageId="0" pageNumber="13" pagination=": 374" refId="B33" refString="Martin-Jimenez, M, Perez-Garcia, A, 2023a. Neuroanatomical study and three-dimensional cranial reconstruction of the Brazilian Albian pleurodiran turtle Euraxemys essweini. Diversity 15 (3): 374, DOI: https://doi.org/10.3390/d15030374" title="Neuroanatomical study and three-dimensional cranial reconstruction of the Brazilian Albian pleurodiran turtle Euraxemys essweini." url="https://doi.org/10.3390/d15030374" volume="15" year="2023 a">2023a</bibRefCitation>
,
<bibRefCitation id="C275109B1866273EAEBBA968FE3F4D0B" DOI="https://doi.org/10.1002/ar.25217" author="Martin-Jimenez, M" journalOrPublisher="Diversity" pageId="0" pageNumber="13" refId="B34" refString="Martin-Jimenez, M, Perez-Garcia, A, 2023b. Neuroanatomical study of the podocnemidid turtle Neochelys arenarum (Pleurodira), from the early Eocene of France. The Anatomical Record: 1-13. https://doi.org/10.1002/ar.25217" title="Neuroanatomical study of the podocnemidid turtle Neochelys arenarum (Pleurodira), from the early Eocene of France. The Anatomical Record: 1 - 13." url="https://doi.org/10.1002/ar.25217" year="2023 b">2023b</bibRefCitation>
;
<bibRefCitation id="09D5EB1A7F9B6DD5846F803F83EB88EF" DOI="https://doi.org/10.1186/s13358-021-00234-y" author="Rollot, Y" journalOrPublisher="Swiss Journal of Palaeontology" pageId="0" pageNumber="13" pagination="1 - 30" refId="B42" refString="Rollot, Y, Evers, SW, Joyce, WG, 2021b. A redescription of the Late Jurassic (Tithonian) turtle Uluops uluops and a new phylogenetic hypothesis of Paracryptodira. Swiss Journal of Palaeontology 140 (1): 1 - 30, DOI: https://doi.org/10.1186/s13358-021-00234-y" title="A redescription of the Late Jurassic (Tithonian) turtle Uluops uluops and a new phylogenetic hypothesis of Paracryptodira." url="https://doi.org/10.1186/s13358-021-00234-y" volume="140" year="2021 b">Rollot et al. 2021b</bibRefCitation>
;
<bibRefCitation id="2E24FE52027BBFDFEAF424E5000FABC5" DOI="https://doi.org/10.1002/ar.25185" author="Smith, HF" journalOrPublisher="The Anatomical Record" pageId="0" pageNumber="13" pagination="1431 - 1451" refId="B43" refString="Smith, HF, Berg, M, Adrian, B, 2023. A well-preserved cranium from the Judith River Formation (Montana, USA) reveals the inner ear and neuroanatomy of a Campanian baenid turtle. The Anatomical Record 306 (6): 1431 - 1451, DOI: https://doi.org/10.1002/ar.25185" title="A well-preserved cranium from the Judith River Formation (Montana, USA) reveals the inner ear and neuroanatomy of a Campanian baenid turtle." url="https://doi.org/10.1002/ar.25185" volume="306" year="2023">Smith et al. 2023</bibRefCitation>
). The lateral semicircular canal is the shortest of the three, only forming a proper canal along the posterior half of the labyrinth that is barely detached from the vestibule, which results in a narrow, dorsoventral opening between the lateral canal and the vestibule (Fig.
<figureCitation id="938B99A43DBD4DEDEEEB71DCE850D47A" captionStart="Figure 6" captionStartId="F6" captionText="Figure 6. Three-dimensional renderings of the left endosseous labyrinth of BSPG 1991 II 113. A. Lateral view; B. Posterior view; C. Dorsal view. Abbreviations: asc, anterior semicircular canal; cc, common crus; fov, fenestra ovalis; lam, lateral ampulla; lsc, lateral semicircular canal; psc, posterior semicircular canal; scc, secondary common crus." figureDoi="10.3897/fr.27.115046.figure6" httpUri="https://binary.pensoft.net/fig/961962" pageId="0" pageNumber="13">6C</figureCitation>
). Anteriorly, the lateral canal merges with a large lateral ampulla. The morphology of the endosseous labyrinth of BSPG 1991 II 130 is extremely similar to that of NHMUK 1903.7.10.1 (
<taxonomicName id="DF0FEF0615CC9370AB574E3A29400348" authorityName="Ramsay" authorityYear="1886" class="Reptilia" family="Carettochelyidae" genus="Carettochelys" higherTaxonomySource="CoL" kingdom="Animalia" lsidName="Carettochelys insculpta" order="Testudines" pageId="0" pageNumber="13" phylum="Chordata" rank="species" species="insculpta">
<emphasis id="089941382DDC524FDC6277BF69ACC88C" italics="true" pageId="0" pageNumber="13">Carettochelys insculpta</emphasis>
</taxonomicName>
). We are only able to identify two very subtle differences between the two endosseous labyrinths, namely a slightly thicker anterior semicircular canal in BSPG 1991 II 130 and a slightly more excavated dorsal embayment of the common crus appears BSPG 1991 II 130.
</paragraph>
<caption id="BD1A20EE35654167902A9E32BFE341EA" doi="10.3897/fr.27.115046.figure6" httpUri="https://binary.pensoft.net/fig/961962" pageId="0" pageNumber="13" start="Figure 6" startId="F6">
<paragraph id="1B2D9663D912864572680A560C5FAA71" pageId="0" pageNumber="13">
<emphasis id="1B8CDB63E87EBF48E3906670B4C94A3D" bold="true" pageId="0" pageNumber="13">Figure 6.</emphasis>
Three-dimensional renderings of the left endosseous labyrinth of BSPG 1991 II 113.
<emphasis id="2F1400B55FB1FB8C01F741186A03C3B3" bold="true" pageId="0" pageNumber="13">A.</emphasis>
Lateral view;
<emphasis id="17D5C7F4374F96CB558E3CC8F04673F1" bold="true" pageId="0" pageNumber="13">B.</emphasis>
Posterior view;
<emphasis id="C649CED70CE47867CD2498D4EEEBF69F" bold="true" pageId="0" pageNumber="13">C.</emphasis>
Dorsal view. Abbreviations: asc, anterior semicircular canal; cc, common crus; fov, fenestra ovalis; lam, lateral ampulla; lsc, lateral semicircular canal; psc, posterior semicircular canal; scc, secondary common crus.
</paragraph>
</caption>
</subSubSection>
</treatment>
</document>
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