<documentid="C82D141159A3B2344343C28855DFDDF5"ID-CLB-Dataset="298405"ID-DOI="10.5194/fr-24-275-2021"ID-GBIF-Dataset="e05b0e97-dfc3-4026-89bb-f4345dda5f41"ID-ISSN="2193-0074"ID-Zenodo-Dep="11359902"IM.bibliography_approvedBy="valdenar"IM.illustrations_approvedBy="valdenar"IM.materialsCitations_approvedBy="felipe"IM.metadata_approvedBy="felipe"IM.tables_approvedBy="valdenar"IM.taxonomicNames_approvedBy="felipe"IM.treatments_approvedBy="valdenar"checkinTime="1716846940112"checkinUser="felipe"docAuthor="Godfrey, Stephen J., Gutstein, Carolina S. & Morgan Iii, Donald J."docDate="2021"docId="03977205FFB86E676436F902CDB2F9D9"docLanguage="en"docName="FossRec.24.2.275-285.pdf"docOrigin="Fossil Record 24 (2)"docSource="http://dx.doi.org/10.5194/fr-24-275-2021"docStyle="DocumentStyle:1B3764FFAC190C6D25C29F616DE4358D.2:FossRec.2014-2021.journal_article"docStyleId="1B3764FFAC190C6D25C29F616DE4358D"docStyleName="FossRec.2014-2021.journal_article"docStyleVersion="2"docTitle="Isoninia Godfrey & Gutstein & Morgan Iii 2021, gen. nov."docType="treatment"docVersion="7"lastPageNumber="279"masterDocId="FFAE0A7DFFB96E63675FFFBCC926FFA1"masterDocTitle="A new odontocete (Inioidea, Odontoceti) from the late Neogene of North Carolina, USA"masterLastPageNumber="285"masterPageNumber="275"pageNumber="276"updateTime="1718200471642"updateUser="ExternalLinkService"zenodo-license-document="CC-BY-4.0">
<mods:namePartid="EC0F7CDF1D09912FB07C8108DFE0AD43">Godfrey, Stephen J.</mods:namePart>
<mods:affiliationid="9CC447147EEED4C55D7088AA8CFCDFB6">Carolina S. Gutstein & Department of Paleontology, Calvert Marine Museum, P. O. Box 97, Solomons, Maryland, 20688, USA & Carolina S. Gutstein & Donald J. Morgan III & Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington,</mods:affiliation>
<mods:affiliationid="489891CD2245B8EC08A295FCC72C4E62">Carolina S. Gutstein & Donald J. Morgan III & Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, & Donald J. Morgan III & Red Paleontológica U. Chile, Laboratorio de Ontogenia y Filogenia, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Ñuaeoa, Santiago, Chile & Donald J. Morgan III & Paleosuchus Ltda, Huelen 161, oficina C, Providencia, Santiago, Chile</mods:affiliation>
<mods:namePartid="E6FA70ADEEC144220A6DDD7A628A9609">Morgan Iii, Donald J.</mods:namePart>
<mods:affiliationid="955CD807A6BCC27E13D4A39E6AF758D4">Carolina S. Gutstein & Department of Paleontology, Calvert Marine Museum, P. O. Box 97, Solomons, Maryland, 20688, USA</mods:affiliation>
<taxonomicNameid="4C3EB890FFB86E6264ECF902CD2CF977"authority="Godfrey & Gutstein & Morgan Iii, 2021"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[947,1034,1726,1750]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="1"pageNumber="276"phylum="Chordata"rank="genus"status="gen. nov.">
<figureCitationid="1305DF96FFB86E626436F951CA97F8A5"box="[873,945,1773,1796]"captionStart="Figure 2"captionStartId="4.[124,191,973,995]"captionTargetBox="[226,1360,177,942]"captionTargetId="figure-15@4.[226,1360,177,942]"captionTargetPageId="4"captionText="Figure 2. Isoninia borealis (gen. nov., sp. nov.). (a) Partial skull CMM-V-4061 in dorsal view lightly coated with sublimed ammonium chloride. (b) Interpretative drawing of (a)."figureDoi="http://doi.org/10.5281/zenodo.11359908"httpUri="https://zenodo.org/record/11359908/files/figure.png"pageId="1"pageNumber="276">Figs. 2</figureCitation>
and
<figureCitationid="1305DF96FFB86E6264BAF951CAD4F8A5"box="[997,1010,1773,1796]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="1"pageNumber="276">3</figureCitation>
<taxonomicNameid="4C3EB890FFB86E62646CF8D5CAC1F820"authority="Godfrey & Gutstein & Morgan Iii, 2021"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[819,999,1897,1921]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="1"pageNumber="276"phylum="Chordata"rank="species"species="borealis"status="sp. nov.">
), also known as the boto or pink river dolphin. The species name
<taxonomicNameid="4C3EB890FFBB6E61664DFE33C852FE07"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[274,372,399,422]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="2"pageNumber="277"phylum="Chordata"rank="species"species="borealis">“borealis</taxonomicName>
<figureCitationid="1305DF96FFBB6E616680FDF3CB0AFDC7"box="[479,556,591,614]"captionStart="Figure 2"captionStartId="4.[124,191,973,995]"captionTargetBox="[226,1360,177,942]"captionTargetId="figure-15@4.[226,1360,177,942]"captionTargetPageId="4"captionText="Figure 2. Isoninia borealis (gen. nov., sp. nov.). (a) Partial skull CMM-V-4061 in dorsal view lightly coated with sublimed ammonium chloride. (b) Interpretative drawing of (a)."figureDoi="http://doi.org/10.5281/zenodo.11359908"httpUri="https://zenodo.org/record/11359908/files/figure.png"pageId="2"pageNumber="277">Figs. 2</figureCitation>
and
<figureCitationid="1305DF96FFBB6E616537FDF3CB51FDC7"box="[616,631,591,614]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="2"pageNumber="277">3</figureCitation>
). It consists of an incomplete skull, preserving the posterior facial region, from the lateral margins of the bony nares to the supraoccipital, including the vertex. Ventrally, part of the vomer/presphenoid complex is also preserved. This specimen was alluded to by
<bibRefCitationid="EFAFBEE2FFBB6E61662EFD52CB63FCA4"author="Geisler, J. H. & Godfrey, S. J. & Lambert, O."box="[369,581,750,773]"pageId="2"pageNumber="277"pagination="198 - 211"refId="ref8182"refString="Geisler, J. H., Godfrey, S. J., and Lambert, O.: A new genus and species of Late Miocene inioid (Cetacea: Odontoceti) from the Meherrin River, North Carolina, U. S. A., J. Vertebr. Paleontol., 32, 198 - 211, 2012."type="journal article"year="2012">Geisler et al. (2012)</bibRefCitation>
prior to it having been assigned a
<collectionCodeid="ED2F5BD6FFBB6E616676FCB2C84CFC84"box="[297,362,782,805]"country="Brazil"httpUri="http://grbio.org/cool/e1dy-v5iv"name="Culture Collection of Phytopathogenic Fungi (Colecao de Culturas de Fungos Fitopatogenicos Prof. Maria Menezes)"pageId="2"pageNumber="277">CMM</collectionCode>
catalogue number: “Other odontocete cranial elements are known from the same locality. However, they cannot be assigned to the present taxon either because they do not overlap with the aforementioned specimens that constitute the hypodigm or because of the presence of at least one other comparably sized but currently undescribed inioid from the same locality” (
<bibRefCitationid="EFAFBEE2FFBB6E6166DBFC71CB74FC45"author="Geisler, J. H. & Godfrey, S. J. & Lambert, O."box="[388,594,973,996]"pageId="2"pageNumber="277"pagination="198 - 211"refId="ref8182"refString="Geisler, J. H., Godfrey, S. J., and Lambert, O.: A new genus and species of Late Miocene inioid (Cetacea: Odontoceti) from the Meherrin River, North Carolina, U. S. A., J. Vertebr. Paleontol., 32, 198 - 211, 2012."type="journal article"year="2012">Geisler et al., 2012</bibRefCitation>
Stratigraphy of the marine late Miocene to Pliocene of North Carolina, USA, showing the Cobham Bay Member of the Eastover Formation, from which CMM-V-4061, the holotype and only known specimen of
<taxonomicNameid="4C3EB890FFBB6E616373FD4ECDE9FCA6"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[1068,1231,754,775]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="2"pageNumber="277"phylum="Chordata"rank="species"species="borealis">
(gen. nov., sp. nov.), is thought to be derived. From
<bibRefCitationid="EFAFBEE2FFBB6E61631CFCACCC22FC84"author="Geisler, J. H. & Godfrey, S. J. & Lambert, O."box="[1091,1284,784,805]"pageId="2"pageNumber="277"pagination="198 - 211"refId="ref8182"refString="Geisler, J. H., Godfrey, S. J., and Lambert, O.: A new genus and species of Late Miocene inioid (Cetacea: Odontoceti) from the Meherrin River, North Carolina, U. S. A., J. Vertebr. Paleontol., 32, 198 - 211, 2012."type="journal article"year="2012">Geisler et al. (2012)</bibRefCitation>
, which they modified from
<bibRefCitationid="EFAFBEE2FFBB6E6164CDFC91CDB4FCE3"author="Ward, L. W. & Andrews, G. W."box="[914,1170,813,834]"pageId="2"pageNumber="277"refId="ref10110"refString="Ward, L. W. and Andrews, G. W.: Stratigraphy of the Calvert, Choptank, and St. Marys Formations (Miocene) in the Chesapeake Bay area, Maryland and Virginia, Virginia Museum of Natural History, Memoir Number 9, 60 pp., 2008."type="book"year="2008">Ward and Andrews (2008)</bibRefCitation>
was recovered by Ronald Ison (from the same location where the type and referred specimens of
<taxonomicNameid="4C3EB890FFBB6E616723FB30C814FB05"authorityName="Geisler, Godfrey, and Lambert"authorityYear="2012"box="[124,306,1164,1188]"class="Mammalia"family="Platanistidae"genus="Meherrinia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="2"pageNumber="277"phylum="Chordata"rank="species"species="isoni">
<bibRefCitationid="EFAFBEE2FFBB6E6166B7FB31CB9DFB05"author="Geisler, J. H. & Godfrey, S. J. & Lambert, O."box="[488,699,1165,1188]"pageId="2"pageNumber="277"pagination="198 - 211"refId="ref8182"refString="Geisler, J. H., Godfrey, S. J., and Lambert, O.: A new genus and species of Late Miocene inioid (Cetacea: Odontoceti) from the Meherrin River, North Carolina, U. S. A., J. Vertebr. Paleontol., 32, 198 - 211, 2012."type="journal article"year="2012">Geisler et al., 2012</bibRefCitation>
) from the bed of the Meherrin River – a tributary of the Chowan River, Murfreesboro, Hertford County,
<collectingRegionid="49FA0DF1FFBB6E616543FB70CB99FB42"box="[540,703,1228,1251]"country="United States of America"name="North Carolina"pageId="2"pageNumber="277">North Carolina</collectingRegion>
,
<collectingCountryid="F3298383FFBB6E616596FB70CBD8FB42"box="[713,766,1228,1251]"name="United States of America"pageId="2"pageNumber="277">USA</collectingCountry>
). More detailed locality information is available from the authors to qualified individuals upon request. Unfortunately, the specimen was not found in situ and was devoid of entombing sediment, as were all specimens of
<taxonomicNameid="4C3EB890FFBB6E616648FAD7CBA1FA22"authority="(Geisler et al., 2012)"baseAuthorityName="Geisler"baseAuthorityYear="2012"box="[279,647,1387,1411]"class="Mammalia"family="Platanistidae"genus="Meherrinia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="2"pageNumber="277"phylum="Chordata"rank="genus">
<bibRefCitationid="EFAFBEE2FFBB6E6166FDFAD0CBA6FA22"author="Geisler, J. H. & Godfrey, S. J. & Lambert, O."box="[418,640,1388,1411]"pageId="2"pageNumber="277"pagination="198 - 211"refId="ref8182"refString="Geisler, J. H., Godfrey, S. J., and Lambert, O.: A new genus and species of Late Miocene inioid (Cetacea: Odontoceti) from the Meherrin River, North Carolina, U. S. A., J. Vertebr. Paleontol., 32, 198 - 211, 2012."type="journal article"year="2012">Geisler et al., 2012</bibRefCitation>
)
</taxonomicName>
. Nevertheless, it is considered to have been locally derived from the Cobham Bay Member of the Eastover Formation (upper Miocene, Messinian) (Lauck W. Ward, personal communication,
<dateid="FF80E5D3FFBB6E616794FA57C8BCF9A3"box="[203,410,1515,1538]"pageId="2"pageNumber="277"value="2009-11-30">30 November 2009</date>
) (
<figureCitationid="1305DF96FFBB6E6166EFFA57C8C9F9A3"box="[432,495,1515,1538]"captionStart="Figure 1"captionStartId="2.[819,886,666,688]"captionTargetBox="[914,1368,177,635]"captionTargetId="figure-472@2.[914,1368,177,635]"captionTargetPageId="2"captionText="Figure 1. Stratigraphy of the marine late Miocene to Pliocene of North Carolina, USA, showing the Cobham Bay Member of the Eastover Formation, from which CMM-V-4061, the holotype and only known specimen of Isoninia borealis (gen. nov., sp. nov.), is thought to be derived. From Geisler et al. (2012), which they modified from Ward and Andrews (2008)."figureDoi="http://doi.org/10.5281/zenodo.11359906"httpUri="https://zenodo.org/record/11359906/files/figure.png"pageId="2"pageNumber="277">Fig. 1</figureCitation>
). Because it was not collected in situ, it is possible that it could have come from the Pliocene Yorktown Formation, but according to Ward (personal communication,
<dateid="FF80E5D3FFBB6E616630F9F7CB19F9C3"box="[367,575,1611,1634]"pageId="2"pageNumber="277"value="2009-11-30">30 November 2009</date>
) this derivation is less likely because of where along the river bed the specimen was recovered. Conservatively, the specimen can be considered to have come from a time interval encompassing the upper Tortonian (Miocene, i.e., the Claremont Manor Member of the Eastover Formation) to the lower Piacenzian (Pliocene). As in
<bibRefCitationid="EFAFBEE2FFBB6E616663F8B6CB3FF880"author="Geisler, J. H. & Godfrey, S. J. & Lambert, O."box="[316,537,1802,1825]"pageId="2"pageNumber="277"pagination="198 - 211"refId="ref8182"refString="Geisler, J. H., Godfrey, S. J., and Lambert, O.: A new genus and species of Late Miocene inioid (Cetacea: Odontoceti) from the Meherrin River, North Carolina, U. S. A., J. Vertebr. Paleontol., 32, 198 - 211, 2012."type="journal article"year="2012">Geisler et al. (2012)</bibRefCitation>
, another argument in favor of the derivation of
<taxonomicNameid="4C3EB890FFBB6E6166D2F896C8C2F8E3"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[397,484,1834,1858]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="2"pageNumber="277"phylum="Chordata"rank="genus">
from the Eastover Formation is the observation that specimens of neither
<taxonomicNameid="4C3EB890FFBB6E616522F8F6C99EF820"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="2"pageNumber="277"phylum="Chordata"rank="species"species="borealis">
<taxonomicNameid="4C3EB890FFBB6E6167B8F8D5C8BDF820"authorityName="Geisler, Godfrey, and Lambert"authorityYear="2012"box="[231,411,1897,1921]"class="Mammalia"family="Platanistidae"genus="Meherrinia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="2"pageNumber="277"phylum="Chordata"rank="species"species="isoni">
have been found in the Yorktown Formation despite extensive collection and study of the fauna of the Yorktown Formation at the Nutrien Aurora Phosphate Mine (formerly known as the Lee Creek Mine, Aurora,
<collectingRegionid="49FA0DF1FFBB6E616227FC7FCAB6FC5B"country="United States of America"name="North Carolina"pageId="2"pageNumber="277">North Carolina</collectingRegion>
) for more than 40 years (
<bibRefCitationid="EFAFBEE2FFBB6E6163C8FC5FCA4BFBBB"author="Whitmore Jr., F. C. & Kaltenbach, J. A."pageId="2"pageNumber="277"pagination="181 - 269"refId="ref10165"refString="Whitmore Jr., F. C. and Kaltenbach, J. A.: Neogene Cetacea of the Lee Creek Phosphate Mine, North Carolina, Virginia Museum of Natural History Special Publication, 14, 181 - 269, 2008."type="journal article"year="2008">Whitmore and Kaltenbach, 2008</bibRefCitation>
<taxonomicNameid="4C3EB890FFBB6E61646CFBCBCAACFB2E"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[819,906,1143,1167]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="2"pageNumber="277"phylum="Chordata"rank="genus">
is diagnosed on the basis of the following unique combination of features, most of which are not apomorphic: anteriorly retracted premaxillae and maxillae (i.e., no contact between premaxillae and nasals and maxillae retracted anteriorly from the sides of the frontals below the vertex); large posterior-most dorsal infraorbital foramen at approximately the same level with posterior margin of external bony nares; robust nasals, anteroposteriorly longer than transversely wide in dorsal view with
<emphasisid="B94A1F01FFBB6E616352FACACD07FA6F"italics="true"pageId="2"pageNumber="277">ventrolateral margins turned ventromedially to form ridges deeply imbedded within corresponding troughs in frontals</emphasis>
(italicized text represents an apomorphy); nasals large; nasals with transversely convex dorsal surface; dorsal surface of nasals not inflated; elevated, bilaterally compressed nearly symmetrical vertex, narrower than external bony nares; frontals form apex of the vertex; presence of os suturarum (or extra folds of the frontals or a projection of the interparietal) at the vertex; in ventral view, pronounced fossa on ventrolateral face of frontal below and behind postorbital process of frontal for the postorbital lobe of the pterygoid sinus (the postorbital recess).
. These thickened bones along with the degree to which the ventral surfaces of the maxillae and nasals deeply suture to the frontals (
<figureCitationid="1305DF96FFBA6E6066A4FD52CB60FCA4"box="[507,582,750,773]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">Fig. 3c</figureCitation>
<taxonomicNameid="4C3EB890FFBA6E6067A0FCB2C892FC87"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[255,436,782,806]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="3"pageNumber="278"phylum="Chordata"rank="species"species="borealis">
<taxonomicNameid="4C3EB890FFBA6E606574FC91C8C5FCC4"authority=", Godfrey and Barnes, 2008"authorityName=", Godfrey and Barnes"authorityYear="2008"class="Mammalia"family="Iniidae"genus="Stenasodelphis"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="3"pageNumber="278"phylum="Chordata"rank="species"species="russellae">
<bibRefCitationid="EFAFBEE2FFBA6E606798FCF2C8C5FCC4"author="Godfrey, S. J. & Barnes, L. G."box="[199,483,846,869]"pageId="3"pageNumber="278"pagination="520 - 528"refId="ref8429"refString="Godfrey, S. J. and Barnes, L. G.: A new genus and species of Late Miocene pontoporiid dolphin (Cetacea: Odontoceti) from the St. Marys Formation in Maryland, J. Vertebr. Paleontol., 28, 520 - 528, 2008."type="journal article"year="2008">Godfrey and Barnes, 2008</bibRefCitation>
<taxonomicNameid="4C3EB890FFBA6E6067ECFCD1CBAFFC24"authority=", Lambert et al., 2018"authorityName="Lambert"authorityYear="2018"box="[179,649,877,901]"class="Mammalia"genus="Kwanzacetus"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="3"pageNumber="278"phylum="Chordata"rank="species"species="khoisani">
<bibRefCitationid="EFAFBEE2FFBA6E6066F1FCD2CBAFFC24"author="Lambert, O. & Auclair, C. & Cauxeiro, C. & Lopez, M. & Adnet, S."box="[430,649,878,901]"pageId="3"pageNumber="278"pagination="5556"refId="ref9118"refString="Lambert, O., Auclair, C., Cauxeiro, C., Lopez, M., and Adnet, S.: A close relative of the Amazon river dolphin in marine deposits: a new Iniidae from the late Miocene of Angola, 6, e 5556, https: // doi. org / 10.7717 / peerj. 5556, 2018."type="book chapter"year="2018">Lambert et al., 2018</bibRefCitation>
<tdid="76DFA82DFFBA919C67F5FEA2CBA0FE92"box="[170,646,286,307]"gridcol="0"gridrow="1"pageId="3"pageNumber="278">Maximum anteroposterior length of right nasal</td>
<tdid="76DFA82DFFBA919C67F5FEF7CBA0FEC1"box="[170,646,331,352]"gridcol="0"gridrow="2"pageId="3"pageNumber="278">Maximum width of nasals (combined)</td>
<tdid="76DFA82DFFBA919C67F5FE1ACBA0FE79"box="[170,646,422,472]"gridcol="0"gridrow="4"pageId="3"pageNumber="278">Minimum distance between maxillae across the vertex</td>
<tdid="76DFA82DFFBA919C67F5FD87CBA0FDCC"box="[170,646,571,621]"gridcol="0"gridrow="6"pageId="3"pageNumber="278">Dorsoventral thickness of vertex through cerebral midline of supraoccipital up through frontal</td>
Vomer: the anterior-most preserved part of the skull is the prenarial process of the vomer (
<figureCitationid="1305DF96FFBA6E606693FC11CB33FC65"box="[460,533,941,964]"captionStart="Figure 2"captionStartId="4.[124,191,973,995]"captionTargetBox="[226,1360,177,942]"captionTargetId="figure-15@4.[226,1360,177,942]"captionTargetPageId="4"captionText="Figure 2. Isoninia borealis (gen. nov., sp. nov.). (a) Partial skull CMM-V-4061 in dorsal view lightly coated with sublimed ammonium chloride. (b) Interpretative drawing of (a)."figureDoi="http://doi.org/10.5281/zenodo.11359908"httpUri="https://zenodo.org/record/11359908/files/figure.png"pageId="3"pageNumber="278">Figs. 2</figureCitation>
and
<figureCitationid="1305DF96FFBA6E606516FC11CB71FC65"box="[585,599,941,964]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">3</figureCitation>
), which widens conspicuously to the mesorostral canal. Posterior to it is the nasal septum.
Maxilla: only parts of the maxillae adjacent to the nares and nasals are preserved. Here, at least their lateral margins are incomplete. However, with the preserved portion it can be clearly observed that the maxillae are retracted anteriorly such that they do not overlap the frontals immediately adjacent to the vertex (
<figureCitationid="1305DF96FFBA6E60663EFB11C88BFB65"box="[353,429,1197,1220]"captionStart="Figure 2"captionStartId="4.[124,191,973,995]"captionTargetBox="[226,1360,177,942]"captionTargetId="figure-15@4.[226,1360,177,942]"captionTargetPageId="4"captionText="Figure 2. Isoninia borealis (gen. nov., sp. nov.). (a) Partial skull CMM-V-4061 in dorsal view lightly coated with sublimed ammonium chloride. (b) Interpretative drawing of (a)."figureDoi="http://doi.org/10.5281/zenodo.11359908"httpUri="https://zenodo.org/record/11359908/files/figure.png"pageId="3"pageNumber="278">Figs. 2</figureCitation>
and
<figureCitationid="1305DF96FFBA6E6066B8FB11C8D0FB65"box="[487,502,1197,1220]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">3</figureCitation>
). Consequently, there is wide exposure of the frontal lateral to the vertex. Deep interdigitating sutures bind the maxillae and frontals (
<figureCitationid="1305DF96FFBA6E6065FBFB50CBD4FAA2"box="[676,754,1260,1283]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">Fig. 3c</figureCitation>
). A shallow trough on the anterior extremity of the preserved segment of the right maxilla is interpreted as the area that held the posterior extremity of the now-missing premaxilla (
<figureCitationid="1305DF96FFBA6E6067DBFAD0C9EEFA22"box="[132,200,1388,1411]"captionStart="Figure 2"captionStartId="4.[124,191,973,995]"captionTargetBox="[226,1360,177,942]"captionTargetId="figure-15@4.[226,1360,177,942]"captionTargetPageId="4"captionText="Figure 2. Isoninia borealis (gen. nov., sp. nov.). (a) Partial skull CMM-V-4061 in dorsal view lightly coated with sublimed ammonium chloride. (b) Interpretative drawing of (a)."figureDoi="http://doi.org/10.5281/zenodo.11359908"httpUri="https://zenodo.org/record/11359908/files/figure.png"pageId="3"pageNumber="278">Fig. 2</figureCitation>
). This suture indicates that the premaxillae were retracted rostrally such that the posterior-most reach of the premaxillae was approximately level with the mid-point in the length of the external bony nares. The maxillae form the posterolateral margin of the external nares. The thickened posteromedial margin of the maxilla broadly contacts and underlies the lateral margin of the nasal (
<figureCitationid="1305DF96FFBA6E6066ADF997CB58F9E3"box="[498,638,1579,1602]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">Fig. 3a and c</figureCitation>
<taxonomicNameid="4C3EB890FFBA6E60651AF9F6CBDEF9C3"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[581,760,1610,1634]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="3"pageNumber="278"phylum="Chordata"rank="species"species="borealis">
. They are robust elements, each sub-rectangular in outline in both dorsal and lateral views. In dorsal view, their conjoined anterior margin forms the essentially straight posterior margin of the external bony nares. From this position, their combined widest point, they slightly narrow gradually along their lateral borders before turning abruptly medially towards the apex of the vertex. The dorsal surface of the nasals slopes conspicuously towards the bony nares (
<figureCitationid="1305DF96FFBA6E60656BF8F6CBA0F8C0"box="[564,646,1866,1889]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">Fig. 3e</figureCitation>
). The pronounced undercut below the anterior margin of the nasals (
<figureCitationid="1305DF96FFBA6E606464FF0CCAADFF66"box="[827,907,176,199]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">Fig. 3c</figureCitation>
) may have held the now-missing part of the presphenoid that formed the posterodorsal margin of the nasal septum. The lateral margin of each nasal is deeply imbedded ventromedially into the frontal (
<figureCitationid="1305DF96FFBA6E6063EFFEACCDDBFE86"box="[1200,1277,272,295]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">Fig. 3c</figureCitation>
). The frontals are wedged between the posteromedial ends of the nasals.
Frontal: the frontals are the largest bones preserved in
<taxonomicNameid="4C3EB890FFBA6E60646CFED3CACDFE26"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[819,1003,367,391]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="3"pageNumber="278"phylum="Chordata"rank="species"species="borealis">
, occupying most of the dorsal area from the temporo-orbital plate to the back of the vertex (
<figureCitationid="1305DF96FFBA6E606235FE2CCC90FE06"box="[1386,1462,400,423]"captionStart="Figure 2"captionStartId="4.[124,191,973,995]"captionTargetBox="[226,1360,177,942]"captionTargetId="figure-15@4.[226,1360,177,942]"captionTargetPageId="4"captionText="Figure 2. Isoninia borealis (gen. nov., sp. nov.). (a) Partial skull CMM-V-4061 in dorsal view lightly coated with sublimed ammonium chloride. (b) Interpretative drawing of (a)."figureDoi="http://doi.org/10.5281/zenodo.11359908"httpUri="https://zenodo.org/record/11359908/files/figure.png"pageId="3"pageNumber="278">Figs. 2</figureCitation>
and
<figureCitationid="1305DF96FFBA6E60643CFE13CA54FE67"box="[867,882,431,454]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">3</figureCitation>
). The posterodorsal margin of the apex of the vertex may have been slightly eroded postmortem but is otherwise complete. Immediately medial to the preserved lateral margin of the frontal is a conspicuous trough until the margin of the preserved portion of the specimen, interpreted here as homologous to the trough for the posterior-most dorsal infraorbital foramen (the actual foramen is not preserved due to the loss of the lateral portion of the maxilla).
<figureCitationid="1305DF96FFBA6E6063AEFD12CC11FD64"box="[1265,1335,686,709]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">Fig. 3f</figureCitation>
) larger than in any other comparably sized odontocete, so the opening for the posterior-most dorsal infraorbital foramen was also thought to be correspondingly large, most similar to that seen in
<bibRefCitationid="EFAFBEE2FFBA6E6064B3FC92CDE0FCE4"author="Pyenson, N. D. & Velez-Juarbe, J. & Gutstein, C. S. & Little, H. & Vigil, D."box="[1004,1222,814,837]"pageId="3"pageNumber="278"pagination="1227"refId="ref9837"refString="Pyenson, N. D., Velez-Juarbe, J., Gutstein, C. S., Little, H., Vigil, D., and O'dea, A.: Isthminia panamensis, a new fossil inioid (Mammalia, Cetacea) from the Chagres Formation of Panama and the evolution of " river dolphins " in the Americas, PeerJ, 3, e 1227, https: // doi. org / 10.7717 / peerj. 1227, 2015."type="journal article"year="2015">Pyenson et al., 2015</bibRefCitation>
; fig. 3B). Immediately below this trough, ventrolaterally, a fossa for the postorbital lobe of the pterygoid sinus occupies the area on the ventrolateral face of the frontal below and behind the postorbital process of the frontal, (i.e., the postorbital recess in
<figureCitationid="1305DF96FFBA6E606204FC11CC82FC65"box="[1371,1444,941,964]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">Fig. 3f</figureCitation>
Behind the thickened maxilla, the frontal gains wide dorsolateral exposure as it ascends the lateral face of the elevated vertex. The frontals form the narrow and pointed vertex posteromedially. Although the suture between contralateral frontals is located along the sagittal plane, below the vertex they are not symmetrical. A CT-scan image through the vertex transversely (
<figureCitationid="1305DF96FFBA6E6064AFFB31CD66FB05"box="[1008,1088,1165,1188]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">Fig. 3d</figureCitation>
) confirms that the right frontal is thicker than the left and its lateral face is not as concave as is that of its left antimere. A supernumerary ossification is present on the vertex, being similar to structures described in the delphinid
<bibRefCitationid="EFAFBEE2FFBA6E6063EBFAB0CCB4FA82"author="Simies-Lopes, P. C."box="[1204,1426,1292,1315]"pageId="3"pageNumber="278"pagination="652 - 660"refId="ref10066"refString="Simies-Lopes, P. C.: Morfologia do sincranio do boto-cinza, Sotalia guianensis (P. J. van BOnOden) (Cetacea, Delphinidae), Rev. Bras. Zool., 23, 652 - 660, 2006."type="journal article"year="2006">Simıes-Lopes, 2006</bibRefCitation>
)
</taxonomicName>
as os suturarum. It is visible both in photos of the partial skull and in CT scans (
<figureCitationid="1305DF96FFBA6E6064ADFAF0CD19FAC2"box="[1010,1087,1356,1379]"captionStart="Figure 2"captionStartId="4.[124,191,973,995]"captionTargetBox="[226,1360,177,942]"captionTargetId="figure-15@4.[226,1360,177,942]"captionTargetPageId="4"captionText="Figure 2. Isoninia borealis (gen. nov., sp. nov.). (a) Partial skull CMM-V-4061 in dorsal view lightly coated with sublimed ammonium chloride. (b) Interpretative drawing of (a)."figureDoi="http://doi.org/10.5281/zenodo.11359908"httpUri="https://zenodo.org/record/11359908/files/figure.png"pageId="3"pageNumber="278">Figs. 2</figureCitation>
,
<figureCitationid="1305DF96FFBA6E606313FAF0CD8DFAC2"box="[1100,1195,1356,1379]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">3a and d</figureCitation>
). The CT images appear to indicate that it is a separate ossification distinct from the frontals, but lack of clarity engenders caution; it may simply be a fold in the left frontal. This separate ossification could represent an interparietal also present in
<taxonomicNameid="4C3EB890FFBA6E6063A6FA77CCA3FA42"authorityName="Lambert, Auclair, Cauxeiro, Lopez & Adnet"authorityYear="2018"box="[1273,1413,1483,1507]"class="Mammalia"genus="Kwanzacetus"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="3"pageNumber="278"phylum="Chordata"rank="genus">
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<bibRefCitationid="EFAFBEE2FFBA6E606431FA57CD76F9A3"author="Lambert, O. & Auclair, C. & Cauxeiro, C. & Lopez, M. & Adnet, S."box="[878,1104,1515,1538]"pageId="3"pageNumber="278"pagination="5556"refId="ref9118"refString="Lambert, O., Auclair, C., Cauxeiro, C., Lopez, M., and Adnet, S.: A close relative of the Amazon river dolphin in marine deposits: a new Iniidae from the late Miocene of Angola, 6, e 5556, https: // doi. org / 10.7717 / peerj. 5556, 2018."type="book chapter"year="2018">Lambert et al., 2018</bibRefCitation>
)
</taxonomicName>
, as well as
<taxonomicNameid="4C3EB890FFBA6E606388FA57CAC0F983"authority="(Lambert et al., 2020)"baseAuthorityName="Lambert"baseAuthorityYear="2020"class="Mammalia"family="Pontoporiidae"genus="Samaydelphis"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="3"pageNumber="278"phylum="Chordata"rank="genus">
<bibRefCitationid="EFAFBEE2FFBA6E606224FA57CAF8F983"author="Lambert, O. & Collareta, A. & Benites-Palomino, A. & Di Celma, C. & De Muizon, C. & Urbina, M. & Bianucci, G."pageId="3"pageNumber="278"pagination="1043 - 1064"refId="ref9186"refString="Lambert, O., Collareta, A., Benites-Palomino, A., Di Celma, C., De Muizon, C., Urbina, M., and Bianucci, G.: A new small, mesorostrine inioid (Cetacea, Odontoceti, Delphinida) from four upper Miocene localities in the Pisco Basin, Peru, Papers in Paleontology, 7, 1043 - 1064, https: // doi. org / 10.1002 / spp 2.1332, 2020."type="journal article"year="2020">Lambert et al., 2020</bibRefCitation>
Below the vertex beyond the reach of the maxillae is a cluster of foramina that pass posteriorly and sub-horizontally through the frontal into the body of the supraoccipital (
<figureCitationid="1305DF96FFBA6E606464F937CA58F903"box="[827,894,1675,1698]"captionStart="Figure 2"captionStartId="4.[124,191,973,995]"captionTargetBox="[226,1360,177,942]"captionTargetId="figure-15@4.[226,1360,177,942]"captionTargetPageId="4"captionText="Figure 2. Isoninia borealis (gen. nov., sp. nov.). (a) Partial skull CMM-V-4061 in dorsal view lightly coated with sublimed ammonium chloride. (b) Interpretative drawing of (a)."figureDoi="http://doi.org/10.5281/zenodo.11359908"httpUri="https://zenodo.org/record/11359908/files/figure.png"pageId="3"pageNumber="278">Fig. 2</figureCitation>
). The course of at least one larger foramen on either side of the vertex can be followed through the supraoccipital where it turns medially towards the midline of the latter.
The ventral sides of the frontals preserve some of the endocranial cavity (
<figureCitationid="1305DF96FFBA6E6064B3F8B6CD11F880"box="[1004,1079,1802,1825]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">Fig. 3f</figureCitation>
). The ethmoid foramen passes from the anterior face of the cranial cavity anterolaterally towards the orbit. The dorsal rim of the optic canal is preserved posteroventral to the ethmoid foramen (
<figureCitationid="1305DF96FFBA6E6063EBF8D6CC18F820"box="[1204,1342,1898,1921]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="3"pageNumber="278">Fig. 3e and f</figureCitation>
<taxonomicNameid="4C3EB890FFBD6E6767BDFC71C8A0FC43"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[226,390,973,994]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="4"pageNumber="279"phylum="Chordata"rank="species"species="borealis">
Presphenoid and cribriform plate: most of the presphenoid (
<bibRefCitationid="EFAFBEE2FFBD6E6767DCFBDFC812FBDB"author="Ichishima, H."box="[131,308,1123,1146]"pageId="4"pageNumber="279"pagination="1661 - 1674"refId="ref8922"refString="Ichishima, H.: The ethmoid and presphenoid of cetaceans, J. Morphol., 277, 1661 - 1674, https: // doi. org / 10.1002 / jmor. 20615, 2016."type="journal article"year="2016">Ichishima, 2016</bibRefCitation>
) is preserved in
<taxonomicNameid="4C3EB890FFBD6E6766B3FBDFCB84FBDA"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[492,674,1123,1147]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="4"pageNumber="279"phylum="Chordata"rank="species"species="borealis">
<figureCitationid="1305DF96FFBD6E6765ECFBDFCBD8FBDB"box="[691,766,1123,1146]"captionStart="Figure 2"captionStartId="4.[124,191,973,995]"captionTargetBox="[226,1360,177,942]"captionTargetId="figure-15@4.[226,1360,177,942]"captionTargetPageId="4"captionText="Figure 2. Isoninia borealis (gen. nov., sp. nov.). (a) Partial skull CMM-V-4061 in dorsal view lightly coated with sublimed ammonium chloride. (b) Interpretative drawing of (a)."figureDoi="http://doi.org/10.5281/zenodo.11359908"httpUri="https://zenodo.org/record/11359908/files/figure.png"pageId="4"pageNumber="279">Figs. 2</figureCitation>
and
<figureCitationid="1305DF96FFBD6E6767F6FB3FC99EFB3B"box="[169,184,1155,1178]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="4"pageNumber="279">3</figureCitation>
). On the posterior cerebral face of the cribriform plate dorsomedial to the ethmoid foramina are two small ovoid depressions, the long axis of which has an anteroventral– posterodorsal orientation. They may have held small olfactory bulbs (or their vestigial remnants) in life; in any case, these cavities are less well developed as compared to the tiny olfactory bulb cavities preserved in the platanistoid
<taxonomicNameid="4C3EB890FFBD6E676723FADECB68FAD8"authority="(Godfrey et al., 2017)"baseAuthorityName="Godfrey"baseAuthorityYear="2017"box="[124,590,1378,1402]"class="Mammalia"family="Platanistidae"genus="Araeodelphis"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="4"pageNumber="279"phylum="Chordata"rank="species"species="natator">
<bibRefCitationid="EFAFBEE2FFBD6E676634FADECB60FAD8"author="Godfrey, S. J. & Barnes, L. G. & Lambert, O."box="[363,582,1378,1401]"pageId="4"pageNumber="279"pagination="1278607"refId="ref8482"refString="Godfrey, S. J., Barnes, L. G., and Lambert, O.: The identity of the Early Miocene dolphin Araeodelphis natator Kellogg, 1957 (Cetacea; Platanistidae), from the Calvert Formation, J. Vertebr. Paleontol., 37, e 1278607, https: // doi. org / 10.1080 / 02724634.2017.1278607, 2017."type="journal article"year="2017">Godfrey et al., 2017</bibRefCitation>
)
</taxonomicName>
. Extending from each of these depressions is a trough that merges into a single one dorsomedially. Minute foramina pass from these depressions and conjoining troughs through the cribriform plate to the nasal cavity (
<figureCitationid="1305DF96FFBD6E676603FA5EC8D3FA58"box="[348,501,1506,1529]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="4"pageNumber="279">Fig. 3b and f</figureCitation>
). Nevertheless, it is not known whether these tiny foramina through the cribriform plate actually conducted olfactory axons to olfactory receptor tissue within the nasal cavity (see
<bibRefCitationid="EFAFBEE2FFBD6E676552F9FDCB9AF9F9"author="Ichishima, H."box="[525,700,1601,1624]"pageId="4"pageNumber="279"pagination="1661 - 1674"refId="ref8922"refString="Ichishima, H.: The ethmoid and presphenoid of cetaceans, J. Morphol., 277, 1661 - 1674, https: // doi. org / 10.1002 / jmor. 20615, 2016."type="journal article"year="2016">Ichishima, 2016</bibRefCitation>
, p. 6). Unlike
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VP 3338 (an unnamed platanistoid odontocete from the latest Oligocene of
<bibRefCitationid="EFAFBEE2FFBD6E676512F93DCBEDF939"author="Hoch, E."box="[589,715,1665,1688]"pageId="4"pageNumber="279"pagination="67 - 89"refId="ref8805"refString="Hoch, E.: Olfaction in whales: evidence from a young odontocete of the late Oligocene north sea, Hist. Biol., 14, 67 - 89, 2000."type="journal article"year="2000">Hoch, 2000</bibRefCitation>
<bibRefCitationid="EFAFBEE2FFBD6E67667AF91DC8E0F919"author="Godfrey, S. J."box="[293,454,1697,1720]"pageId="4"pageNumber="279"pagination="519 - 530"refId="ref8392"refString="Godfrey, S. J.: On the olfactory apparatus in the Miocene odontocete Squalodon sp. (Squalodontidae), C. R. Palevol., 12, 519 - 530, 2013."type="journal article"year="2013">Godfrey, 2013</bibRefCitation>
), there is no development of crescentic foramina or ethmoturbinals on the anterior side of the ectethmoid in
<taxonomicNameid="4C3EB890FFBD6E676639F95CC89BF959"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[358,445,1760,1784]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="4"pageNumber="279"phylum="Chordata"rank="genus">
<taxonomicNameid="4C3EB890FFBD6E676518F95CCBD8F959"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[583,766,1760,1784]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="4"pageNumber="279"phylum="Chordata"rank="species"species="borealis">
seems to be more derived in the complete loss of these structures over the two aforementioned osmatic odontocetes. Although the derived condition in
<taxonomicNameid="4C3EB890FFBD6E676680F8FCCB10F8F9"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[479,566,1856,1880]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="4"pageNumber="279"phylum="Chordata"rank="genus">
Supraoccipital: a robust supraoccipital is wedged deeply between and behind the frontals (
<figureCitationid="1305DF96FFBD6E6763EFFB1FCDD0FB1B"box="[1200,1270,1187,1210]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="4"pageNumber="279">Fig. 3</figureCitation>
). In dorsal view, the supraoccipital gains wide exposure behind the vertex (
<figureCitationid="1305DF96FFBD6E676464FB5FCAADFB5B"box="[827,907,1251,1274]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="4"pageNumber="279">Fig. 3a</figureCitation>
). Posterodorsally, the top of the supraoccipital is a step down from the top of the vertex formed by the frontals (
<figureCitationid="1305DF96FFBD6E676464FA9FCAAAFA9B"box="[827,908,1315,1338]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="4"pageNumber="279">Fig. 3e</figureCitation>
). In a posterior view of
<taxonomicNameid="4C3EB890FFBD6E6763C2FA9ECDD2FA9B"authorityName="Godfrey & Gutstein & Morgan Iii"authorityYear="2021"box="[1181,1268,1314,1338]"class="Mammalia"family="Iniidae"genus="Isoninia"higherTaxonomySource="GBIF"kingdom="Animalia"order="Cetacea"pageId="4"pageNumber="279"phylum="Chordata"rank="genus">
, the broken bone suggests the presence of an external occipital crest just below the top of the supraoccipital. A transverse CT scan image through the vertex (
<figureCitationid="1305DF96FFBD6E676368FA3ECDA0FA38"box="[1079,1158,1410,1433]"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="4"pageNumber="279">Fig. 3d</figureCitation>
) shows that the supraoccipital was wedged dorsally between the thickened frontals. In ventral view, the supraoccipital abuts the frontals along their posteromedial margins. Posteriorly, within the brain cavity, the medial part of the supraoccipital becomes increasingly ridge-like (i.e., the internal occipital protuberance;
<figureCitationid="1305DF96FFBD6E676238F99ECA4DF9F9"captionStart="Figure 3"captionStartId="5.[124,191,1650,1672]"captionTargetBox="[188,1397,275,1618]"captionTargetId="figure-15@5.[188,1397,275,1618]"captionTargetPageId="5"captionText="Figure 3. Isoninia borealis (gen. nov., sp. nov.). (a) CMM-V-4061 in dorsal view; anterior to top of figure. (b) Single CT-scan image through CMM-V-4061 in posterior view as indicated by the transverse white line in (a) to which the corresponding arrow is pointing. (c) Single CT-scan image in posterior view through the anterior part of the nasals as indicated by the white line in (a). (d) Single CT-scan image in posterior view through the vertex showing the os suturarum or a fold in the frontals as indicated by the white line in (a). (e) CMM-V-4061 in left lateral view. (f) CMM-V-4061 in ventral view; anterior to top of figure. Specimen lightly coated with sublimed ammonium chloride. CT-scan images (b–d) are adjusted to the scale bar to the left below (a). The scale bar for (e) and (f) is to the left below (f)."figureDoi="http://doi.org/10.5281/zenodo.11359912"httpUri="https://zenodo.org/record/11359912/files/figure.png"pageId="4"pageNumber="279">Fig. 3d and f</figureCitation>
) and in life is presumed to have partially separated the cerebral hemispheres posteriorly.
