532 lines
76 KiB
XML
532 lines
76 KiB
XML
<document id="36966EF070F3EA4E90B6FB8E5DCF3D43" ID-CLB-Dataset="3537" ID-DOI="10.1046/j.1096-3642.2002.00015.x" ID-GBIF-Dataset="33418eac-3f41-4da6-94aa-eafa33222a2e" ID-ISSN="0024-4082" ID-Zenodo-Dep="4687167" IM.materialsCitations_approvedBy="felipe" IM.metadata_approvedBy="felipe" IM.taxonomicNames_approvedBy="felipe" checkinTime="1618408764460" checkinUser="carolina" docAuthor="Muizon, Christian de & Domning, Daryl P." docDate="2002" docId="DE7C305BFF8CFA46F99BFD3DB5B4E8A4" docLanguage="en" docName="ZoolJLinnSoc.134.423-452.pdf" docOrigin="Zoological Journal of the Linnean Society 134 (4)" docSource="https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2002.00015.x" docStyle="DocumentStyle:0DD8C314D74634CE09062A86991413F8.2:ZoolJLinnSoc.2002-2009.journal_article" docStyleId="0DD8C314D74634CE09062A86991413F8" docStyleName="ZoolJLinnSoc.2002-2009.journal_article" docStyleVersion="2" docTitle="Odobenocetops PERUVIANUS MUIZON 1993" docType="treatment" docVersion="8" lastPageNumber="444" masterDocId="22454823FF9CFA53F959FFF8B422EA62" masterDocTitle="The anatomy of Odobenocetops (Delphinoidea, Mammalia), the walrus-like dolphin from the Pliocene of Peru and its palaeobiological implications" masterLastPageNumber="452" masterPageNumber="423" pageNumber="439" updateTime="1698936361855" updateUser="ExternalLinkService" zenodo-license-document="CC-BY-4.0" zenodo-license-figures="CC-BY-4.0">
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<mods:title id="849C93D5D2CC8273C11F028583939768">The anatomy of Odobenocetops (Delphinoidea, Mammalia), the walrus-like dolphin from the Pliocene of Peru and its palaeobiological implications</mods:title>
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<mods:namePart id="398D5F11089C0D425EF92791C027AA10">Muizon, Christian de</mods:namePart>
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<mods:namePart id="AB24D31A3C948FF0D5B65B3E27B4F090">Domning, Daryl P.</mods:namePart>
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<mods:title id="532CB3FA60396AAAEE1B296FB2D078D3">Zoological Journal of the Linnean Society</mods:title>
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<mods:date id="AA73F321BAD9673D82F22E74C5B9A5E0">2002</mods:date>
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<treatment id="DE7C305BFF8CFA46F99BFD3DB5B4E8A4" ID-DOI="http://doi.org/10.5281/zenodo.5700705" ID-GBIF-Taxon="190302705" ID-Zenodo-Dep="5700705" LSID="urn:lsid:plazi:treatment:DE7C305BFF8CFA46F99BFD3DB5B4E8A4" httpUri="http://treatment.plazi.org/id/DE7C305BFF8CFA46F99BFD3DB5B4E8A4" lastPageId="21" lastPageNumber="444" pageId="16" pageNumber="439">
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<subSubSection id="1ECFD2C6FF8CFA43F99BFD3DB6E5E8BF" box="[194,711,709,733]" pageId="16" pageNumber="439" type="nomenclature">
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<paragraph id="566A814DFF8CFA43F99BFD3DB6E5E8BF" blockId="16.[194,711,709,765]" box="[194,711,709,733]" pageId="16" pageNumber="439">
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<heading id="0D223621FF8CFA43F99BFD3DB6E5E8BF" box="[194,711,709,733]" centered="true" fontSize="9" level="2" pageId="16" pageNumber="439" reason="5">
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<taxonomicName id="91D5FACEFF8CFA43F99BFD3DB6E5E8BF" authority="PERUVIANUS MUIZON 1993" authorityName="PERUVIANUS MUIZON" authorityYear="1993" box="[194,711,709,733]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="16" pageNumber="439" phylum="Chordata" rank="genus">
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<emphasis id="64A15D5FFF8CFA43F99BFD3DB603E8B9" box="[194,545,709,733]" italics="true" pageId="16" pageNumber="439">ODOBENOCETOPS PERUVIANUS</emphasis>
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MUIZON 1993
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</taxonomicName>
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</heading>
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</paragraph>
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</subSubSection>
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<subSubSection id="1ECFD2C6FF8CFA46F875FD1DB5B4E8A4" lastPageId="21" lastPageNumber="444" pageId="16" pageNumber="439" type="description">
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<paragraph id="566A814DFF8CFA43F875FD1DB67CE89F" blockId="16.[194,711,709,765]" box="[300,606,741,765]" pageId="16" pageNumber="439">
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(
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<figureCitation id="CEEE9DC8FF8CFA43F86DFD1DB5CBE89F" box="[308,489,741,765]" captionStart-0="Figure 13" captionStart-1="Figure 14" captionStart-2="Figure 15" captionStartId-0="17.[159,238,1371,1392]" captionStartId-1="18.[145,224,1854,1875]" captionStartId-2="19.[823,902,1126,1147]" captionTargetBox-0="[349,1251,194,1339]" captionTargetBox-1="[157,1410,1469,1821]" captionTargetBox-2="[828,1436,197,1094]" captionTargetId-0="figure-258@17.[344,1305,172,1349]" captionTargetId-1="figure-669@18.[139,1420,1459,1855]" captionTargetId-2="figure-601@19.[828,1436,197,1094]" captionTargetPageId-0="17" captionTargetPageId-1="18" captionTargetPageId-2="19" captionText-0="Figure 13. Odobenocetops peruvianus, referred specimen (SMNK PAL 2491). Skull of a probable female in dorsal (A), ventral (B), occipital (D), and anteroventral (E) views; posteroventral view of the anterior region of the palate showing the two small tusks (C)." captionText-1="Figure 14. Odobenocetops peruvianus, referred specimen (SMNK PAL 2491). Skull of a probable female in lateral right (A) and lateral left (B) views." captionText-2="Figure 15. Auditory region of Odobenocetops peruvianus, holotype (SMNK PAL 2491). Lateral view (A) and posterolateral view showing the tympanic aperture (B). On B, the outline of the tympanic aperture has been enhanced with a white line.Abbreviations:Ap, anterior process of the periotic; Bo, basioccipital; Eam, external auditory meatus; Fo, foramen ovale; Gf, glenoid fossa; Oc, occipital condyle; Po, paroccipital process of the exoccipital; Ptp, post-tympanic process of the squamosal; Sp, sigmoid process of the tympanic; Tym, tympanic." figureDoi-0="http://doi.org/10.5281/zenodo.4687211" figureDoi-1="http://doi.org/10.5281/zenodo.4687213" figureDoi-2="http://doi.org/10.5281/zenodo.4687217" httpUri-0="https://zenodo.org/record/4687211/files/figure.png" httpUri-1="https://zenodo.org/record/4687213/files/figure.png" httpUri-2="https://zenodo.org/record/4687217/files/figure.png" pageId="16" pageNumber="439">FIGURES 13–15</figureCitation>
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,
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<tableCitation id="1B57B4F6FF8CFA43F8AFFD1DB677E89F" box="[502,597,741,765]" captionStart="Table 3" captionStartId="16.[145,209,1332,1353]" captionText="Table 3. Measurements of the skull of Odobenocetops peruvianus (SMNK PAL 2491) in mm. (e = estimated)." pageId="16" pageNumber="439">TABLE 3</tableCitation>
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)
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</paragraph>
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<paragraph id="566A814DFF8CFA43F9C8FCF5B65EEE34" blockId="16.[145,761,781,1110]" pageId="16" pageNumber="439">
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A second skull of
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<taxonomicName id="91D5FACEFF8CFA43F805FCF5B6A8E941" box="[348,650,781,803]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="16" pageNumber="439" phylum="Chordata" rank="species" species="peruvianus">
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<emphasis id="64A15D5FFF8CFA43F805FCF5B6A8E941" box="[348,650,781,803]" italics="true" pageId="16" pageNumber="439">Odobenocetops peruvianus</emphasis>
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</taxonomicName>
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has been discovered in the earliest Pliocene beds of the Pisco Formation at Sud-Sacaco. This specimen is of special interest because it is more complete than the
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<typeStatus id="896E3FEFFF8CFA43FBC1FC91B6DBE91D" box="[664,761,873,895]" pageId="16" pageNumber="439" type="holotype">holotype</typeStatus>
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and especially because it bears two small tusks similar in size to the small tusk of the
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<typeStatus id="896E3FEFFF8CFA43FB6BFC5EB6B1E9DE" box="[562,659,934,956]" pageId="16" pageNumber="439" type="holotype">holotype</typeStatus>
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(USNM 488252) and has therefore been regarded as a female of
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<taxonomicName id="91D5FACEFF8CFA43F9F6FC1CB657E998" authority="(de Muizon et al., 1999)" baseAuthorityName="de Muizon" baseAuthorityYear="1999" box="[175,629,996,1018]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="16" pageNumber="439" phylum="Chordata" rank="species" species="peruvianus">
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<emphasis id="64A15D5FFF8CFA43F9F6FC1CB570E99B" box="[175,338,996,1017]" italics="true" pageId="16" pageNumber="439">O. peruvianus</emphasis>
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(
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<bibRefCitation id="3244FCBCFF8CFA43F83DFC1CB64FE998" author="de Muizon C & Domning DP & Parrish M" box="[356,621,996,1018]" pageId="16" pageNumber="439" pagination="449 - 455" refId="ref23136" refString="de Muizon C, Domning DP, Parrish M. 1999. Dimorphic tusks and adaptive strategies in a new species of walrus-like dolphin (Odobenocetopsidae) from the Pliocene of Peru. Comptes-rendus de l'Academie des Sciences, Paris, Sciences de la Terre et des Planetes 329: 449 - 455." type="journal article" year="1999">
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de Muizon
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<emphasis id="64A15D5FFF8CFA43F8B1FC1DB639E99B" box="[488,539,996,1018]" italics="true" pageId="16" pageNumber="439">et al</emphasis>
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., 1999
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</bibRefCitation>
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)
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</taxonomicName>
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. In the following discussion, we do not exhaustively describe the new skull, but simply describe the new features
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<taxonomicName id="91D5FACEFF8CFA43FB86FBDAB532EE37" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="16" pageNumber="439" phylum="Chordata" rank="species" species="peruvianus">
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<emphasis id="64A15D5FFF8CFA43FB86FBDAB532EE37" italics="true" pageId="16" pageNumber="439">O. peruvianus</emphasis>
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</taxonomicName>
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provided by the new specimen.
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</paragraph>
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<paragraph id="566A814DFF8CFA43F9C8FB96B6F8EEC0" blockId="16.[145,761,1134,1186]" pageId="16" pageNumber="439">
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<emphasis id="64A15D5FFF8CFA43F9C8FB96B4D7EEE1" box="[145,245,1134,1155]" italics="true" pageId="16" pageNumber="439">
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<typeStatus id="896E3FEFFF8CFA43F9C8FB96B4D7EEE1" box="[145,245,1134,1155]" pageId="16" pageNumber="439" type="holotype">Holotype</typeStatus>
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</emphasis>
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: USNM 488252, an incomplete skull lacking much of the left side and all of the auditory bones.
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</paragraph>
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<paragraph id="566A814DFF8CFA43F9C8FB42B170EB7A" blockId="16.[145,761,1210,1263]" lastBlockId="16.[809,1425,197,280]" pageId="16" pageNumber="439">
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<emphasis id="64A15D5FFF8CFA43F9C8FB42B550EEB2" box="[145,370,1210,1232]" italics="true" pageId="16" pageNumber="439">Referred specimens</emphasis>
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: SMNK PAL 2491, a relatively complete skull which lacks only the posterodorsal roof of the braincase, and which still retains the ear bones
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<emphasis id="64A15D5FFF8CFA43FA70FF1CB757EA9B" box="[809,885,228,249]" italics="true" pageId="16" pageNumber="439">in situ</emphasis>
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; MNHN SAS 1613, a left periotic and partial tympanic; and MNHN SAS 1614, a left periotic.
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</paragraph>
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<paragraph id="566A814DFF8CFA43FA70FEC8B11CE81B" blockId="16.[809,1425,304,633]" pageId="16" pageNumber="439">
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<emphasis id="64A15D5FFF8CFA43FA70FEC8B024EB27" box="[809,1030,304,325]" italics="true" pageId="16" pageNumber="439">Emended diagnosis</emphasis>
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:
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<taxonomicName id="91D5FACEFF8CFA43FD4DFEC8B163EB24" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" box="[1044,1345,304,326]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="16" pageNumber="439" phylum="Chordata" rank="species" species="peruvianus">
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<emphasis id="64A15D5FFF8CFA43FD4DFEC8B163EB24" box="[1044,1345,304,326]" italics="true" pageId="16" pageNumber="439">Odobenocetops peruvianus</emphasis>
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</taxonomicName>
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differs from
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<taxonomicName id="91D5FACEFF8CFA43FA3FFEA8B7CAEB06" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[870,1000,335,357]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="16" pageNumber="439" phylum="Chordata" rank="species" species="leptodon">
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<emphasis id="64A15D5FFF8CFA43FA3FFEA8B7CAEB06" box="[870,1000,335,357]" italics="true" pageId="16" pageNumber="439">O. leptodon</emphasis>
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</taxonomicName>
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in its snout, which is narrower at its apex and tapers dorsally (although the apex is still rounded); in the presence of large premaxillary foramina, anterior to the nares; in the absence of depressions for premaxillary sacs; in the shorter and shallower palate (especially in the anterior region); in the anterior border of the palate which is more Vshaped whereas it is more U-shaped in
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<taxonomicName id="91D5FACEFF8CFA43FC5CFDDEB1A8E859" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[1285,1418,550,571]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="16" pageNumber="439" phylum="Chordata" rank="species" species="leptodon">
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<emphasis id="64A15D5FFF8CFA43FC5CFDDEB1A8E859" box="[1285,1418,550,571]" italics="true" pageId="16" pageNumber="439">O. leptodon</emphasis>
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</taxonomicName>
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; and in the deeply notched anterodorsal edge of the orbit, which is slightly concave in
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<taxonomicName id="91D5FACEFF8CFA43FDEDFD9BB115E81A" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[1204,1335,611,632]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="16" pageNumber="439" phylum="Chordata" rank="species" species="leptodon">
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<emphasis id="64A15D5FFF8CFA43FDEDFD9BB115E81A" box="[1204,1335,611,632]" italics="true" pageId="16" pageNumber="439">O. leptodon</emphasis>
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</taxonomicName>
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.
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</paragraph>
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<paragraph id="566A814DFF8CFA43FAA2FD4CB09CE8AE" blockId="16.[1019,1214,692,716]" box="[1019,1214,692,716]" pageId="16" pageNumber="439">DESCRIPTION</paragraph>
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<paragraph id="566A814DFF8CFA43FA93FD1BB0CDE898" blockId="16.[970,1263,739,763]" box="[970,1263,739,763]" pageId="16" pageNumber="439">TUSKS AND PREMAXILLAE</paragraph>
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<paragraph id="566A814DFF8CFA43FA70FCF4B7A1EF81" blockId="16.[809,1425,780,1906]" pageId="16" pageNumber="439">
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The major differences between the new specimen and the
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<typeStatus id="896E3FEFFF8CFA43FA0CFCD2B794E922" box="[853,950,810,832]" pageId="16" pageNumber="439" type="holotype">holotype</typeStatus>
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are in the size of the tusks and morphology of the premaxillae. Both tusks are small and the left tusk is slightly smaller in diameter than the right. Neither of the tusks is complete. The left tusk is broken inside the sheath; however, the right tusk is only lacking its apex and, as preserved, is
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<quantity id="912D2CA8FF8CFA43FC4EFC3CB17AE9BB" box="[1303,1368,964,985]" metricMagnitude="-1" metricUnit="m" metricValue="2.3" pageId="16" pageNumber="439" unit="cm" value="23.0">23 cm</quantity>
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long and is probably missing a few cm only. Therefore, the right tusk was very close to the length as well as the diameter of the small left tusk of
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<taxonomicName id="91D5FACEFF8CFA43FDC2FBD8B13EEE57" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[1179,1308,1056,1077]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="16" pageNumber="439" phylum="Chordata" rank="species" species="leptodon">
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<emphasis id="64A15D5FFF8CFA43FDC2FBD8B13EEE57" box="[1179,1308,1056,1077]" italics="true" pageId="16" pageNumber="439">O. leptodon</emphasis>
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</taxonomicName>
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. Although the tusk is not complete, given the length of the tusk (as preserved) and the sheath, it is certain that it was erupted. The premaxillary sheaths are small, and, in agreement with the sizes of the tusks, the left one is smaller than the right. Because of this slight asymmetry and although the apices of the left sheath and tusk are not preserved, it is likely that the left tusk was also erupted. Furthermore, the walls of the left sheath at its apex are very thin, which suggests that very little of the bone is missing. The apex of the right sheath is not completely preserved either, but given the thickness of the bone at the broken extremity, it is probable that no more than a few centimeters are lacking.
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</paragraph>
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<caption id="02AAD1C5FF8CFA43F9C8FACCB6F3EF04" pageId="16" pageNumber="439" startId="16.[145,209,1332,1353]">
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<paragraph id="566A814DFF8CFA43F9C8FACCB6F3EF04" blockId="16.[145,761,1332,1383]" pageId="16" pageNumber="439">
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<emphasis id="64A15D5FFF8CFA43F9C8FACCB4D1EF2B" bold="true" box="[145,243,1332,1353]" pageId="16" pageNumber="439">Table 3.</emphasis>
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Measurements of the skull of
|
||
<taxonomicName id="91D5FACEFF8CFA43FB39FACCB5F0EF04" authority="(SMNK PAL 2491)" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="16" pageNumber="439" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8CFA43FB39FACCB524EF04" italics="true" pageId="16" pageNumber="439">Odobenocetops peruvianus</emphasis>
|
||
(SMNK PAL 2491)
|
||
</taxonomicName>
|
||
in mm. (e = estimated).
|
||
</paragraph>
|
||
</caption>
|
||
<paragraph id="566A814DFF8CFA43F9C8FA74B5BAEFC3" blockId="16.[145,741,1420,1881]" box="[145,408,1420,1441]" pageId="16" pageNumber="439">Basicondylar length: 412</paragraph>
|
||
<paragraph id="566A814DFF8CFA43F9C8FA51B5DCEFDC" blockId="16.[145,741,1420,1881]" box="[145,510,1448,1471]" pageId="16" pageNumber="439">Bizygomatic width: 158 ¥ 2 = 316e</paragraph>
|
||
<paragraph id="566A814DFF8CFA43F9C8FA3EB51FEF9B" blockId="16.[145,741,1420,1881]" pageId="16" pageNumber="439">Minimum width of the skull posterior to the postorbital processes: 116</paragraph>
|
||
<paragraph id="566A814DFF8CFA42FA18FA14B5C9ED56" blockId="16.[809,1425,780,1906]" lastBlockId="17.[159,775,1516,1906]" lastPageId="17" lastPageNumber="440" pageId="16" pageNumber="439">
|
||
The dorsal aspect of the premaxillae is very similar to that of the
|
||
<typeStatus id="896E3FEFFF8CFA43FA8FF9F2B015EC42" box="[982,1079,1546,1568]" pageId="16" pageNumber="439" type="holotype">holotype</typeStatus>
|
||
although slightly more symmetrical. The posterior extension of the right prem axilla behind the nares is only slightly greater than that of the left, contrary to the condition of the
|
||
<typeStatus id="896E3FEFFF8CFA43FC00F99EB77FECF9" pageId="16" pageNumber="439" type="holotype">holotype</typeStatus>
|
||
, in which the posterolateral process of the left premaxilla reaches the middle of the lateral edge of the left naris, whereas the right process almost reaches the posterior edge of the right naris. Since the premaxillae of SMNK PAL 2491 project posteriorly slightly behind the bony naris, this feature shows some variation within the species. The asymmetry of the tusks and alveolar processes may thus be reflected in the asymmetry of the posterior processes of the premaxillae. However, this inference must be made cautiously since most odontocetes (including monodontids) present an asymmetry of the dorsal bones of the skull, the right premaxilla and maxilla extending farther posteriorly than the left and slightly displacing the vertex on the left side of the skull. Nevertheless, the asymmetry of the male narwhal does not reflect the tusk asymmetry since the right maxilla is slightly more expanded posteriorly than the left, which carries the large tusk.
|
||
</paragraph>
|
||
<paragraph id="566A814DFF8CFA43F9C8F9F9B4EFEC51" blockId="16.[145,741,1420,1881]" pageId="16" pageNumber="439">Minimum width between the dorsal edges of the orbits: 123</paragraph>
|
||
<paragraph id="566A814DFF8CFA43F9C8F9C4B6FDEC33" blockId="16.[145,741,1420,1881]" box="[145,735,1596,1617]" pageId="16" pageNumber="439">Maximum width between the postorbital processes: 226</paragraph>
|
||
<paragraph id="566A814DFF8CFA43F9C8F9A1B6EFEC0C" blockId="16.[145,741,1420,1881]" box="[145,717,1625,1646]" pageId="16" pageNumber="439">Width of the snout between the antorbital notches: 87</paragraph>
|
||
<paragraph id="566A814DFF8CFA43F9C8F98EB5D8ECE9" blockId="16.[145,741,1420,1881]" box="[145,506,1654,1675]" pageId="16" pageNumber="439">Maximum width of both nares: 60</paragraph>
|
||
<paragraph id="566A814DFF8CFA43F9C8F96CB61CECCB" blockId="16.[145,741,1420,1881]" box="[145,574,1684,1705]" pageId="16" pageNumber="439">Maximum length of the right naris: 51.5</paragraph>
|
||
<paragraph id="566A814DFF8CFA43F9C8F949B5BBECA4" blockId="16.[145,741,1420,1881]" box="[145,409,1713,1734]" pageId="16" pageNumber="439">Width of the choanae: 96</paragraph>
|
||
<paragraph id="566A814DFF8CFA43F9C8F936B577ED63" blockId="16.[145,741,1420,1881]" pageId="16" pageNumber="439">Maximum width of the skull at the level of the exoccipitals: 250</paragraph>
|
||
<paragraph id="566A814DFF8CFA43F9C8F8F1B558ED7C" blockId="16.[145,741,1420,1881]" box="[145,378,1801,1822]" pageId="16" pageNumber="439">Bicondylar width: 143</paragraph>
|
||
<paragraph id="566A814DFF8CFA43F9C8F8DEB6C7ED59" blockId="16.[145,741,1420,1881]" box="[145,741,1830,1851]" pageId="16" pageNumber="439">Width between the apices of the hamular processes: 128</paragraph>
|
||
<paragraph id="566A814DFF8CFA43F9C8F8BCB693ED3B" blockId="16.[145,741,1420,1881]" box="[145,689,1860,1881]" pageId="16" pageNumber="439">Length of the lateral lobe of the left tympanic: 48.5</paragraph>
|
||
<caption id="02AAD1C5FF8DFA42F9C6FAA3B556EFC9" ID-DOI="http://doi.org/10.5281/zenodo.4687211" ID-Zenodo-Dep="4687211" httpUri="https://zenodo.org/record/4687211/files/figure.png" pageId="17" pageNumber="440" startId="17.[159,238,1371,1392]" targetBox="[349,1251,194,1339]" targetPageId="17">
|
||
<paragraph id="566A814DFF8DFA42F9C6FAA3B556EFC9" blockId="17.[159,1439,1371,1451]" pageId="17" pageNumber="440">
|
||
<emphasis id="64A15D5FFF8DFA42F9C6FAA3B535EF12" bold="true" box="[159,279,1371,1392]" pageId="17" pageNumber="440">Figure 13.</emphasis>
|
||
<taxonomicName id="91D5FACEFF8DFA42F87AFAA3B618EF12" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" box="[291,570,1371,1392]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="17" pageNumber="440" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8DFA42F87AFAA3B618EF12" box="[291,570,1371,1392]" italics="true" pageId="17" pageNumber="440">Odobenocetops peruvianus</emphasis>
|
||
</taxonomicName>
|
||
, referred specimen (SMNK PAL 2491). Skull of a probable female in dorsal (A), ventral (B), occipital (D), and anteroventral (E) views; posteroventral view of the anterior region of the palate showing the two small tusks (C).
|
||
</paragraph>
|
||
</caption>
|
||
<paragraph id="566A814DFF8DFA41F9E1F8C6B646E8EA" blockId="17.[159,775,1516,1906]" lastBlockId="18.[145,761,197,955]" lastPageId="18" lastPageNumber="441" pageId="17" pageNumber="440">
|
||
In SMNK PAL 2491 the snout is very complete and the structure of the bone is perfectly preserved. Therefore, muscle scars and foramina are clearly observable and provide important data. Anterior to the large premaxillary foramina is a rough, triangular surface, distinct on each bone, which reaches the apex of the snout. This area corresponds to the attachment scar for the nasal plug muscle in the other odontocetes. These muscle scars are so well marked that it is unlikely that there was no nasal plug muscle in
|
||
<taxonomicName id="91D5FACEFF8DFA42FCDCF93BB794EC95" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="17" pageNumber="440" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8DFA42FCDCF93BB794EC95" italics="true" pageId="17" pageNumber="440">O. peruvianus</emphasis>
|
||
</taxonomicName>
|
||
. It is therefore very probable that
|
||
<taxonomicName id="91D5FACEFF8DFA42FC1BF919B7A1ED77" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="17" pageNumber="440" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8DFA42FC1BF919B7A1ED77" italics="true" pageId="17" pageNumber="440">O. peruvianus</emphasis>
|
||
</taxonomicName>
|
||
had nasal plugs, which is to be expected in an odontocete, but was not clear on the
|
||
<typeStatus id="896E3FEFFF8DFA42FC54F8E6B14CED56" box="[1293,1390,1822,1844]" pageId="17" pageNumber="440" type="holotype">holotype</typeStatus>
|
||
(
|
||
<bibRefCitation id="3244FCBCFF8DFA42FCDDF8E6B005ED31" author="de Muizon C & Domning DP & Ketten DR" pageId="17" pageNumber="440" refId="ref23097" refString="de Muizon C, Domning DP, Ketten DR. 2002. Odobenocetops peruvianus, the walrus-convergent delphinoid (Cetacea, Mammalia) from the lower Pliocene of Peru. Smithsonian Contribution to Paleobiology 93: in press." type="book" year="2002">
|
||
de Muizon
|
||
<emphasis id="64A15D5FFF8DFA42FAC3F8C6B7F3ED30" box="[922,977,1853,1875]" italics="true" pageId="17" pageNumber="440">et al</emphasis>
|
||
., 2002
|
||
</bibRefCitation>
|
||
). Posterior to the premaxillary foramina are two short saddle-shaped grooves, which form the anterior edges of the bony nares. The morphology of the new specimen confirms the conclusions of
|
||
<bibRefCitation id="3244FCBCFF8EFA41F9E9FEFAB5E1EB7B" author="de Muizon C & Domning DP & Ketten DR" box="[176,451,258,281]" pageId="18" pageNumber="441" refId="ref23097" refString="de Muizon C, Domning DP, Ketten DR. 2002. Odobenocetops peruvianus, the walrus-convergent delphinoid (Cetacea, Mammalia) from the lower Pliocene of Peru. Smithsonian Contribution to Paleobiology 93: in press." type="book" year="2002">
|
||
de Muizon
|
||
<emphasis id="64A15D5FFF8EFA41F86FFEFBB548EB75" box="[310,362,258,280]" italics="true" pageId="18" pageNumber="441">et al</emphasis>
|
||
. (2002)
|
||
</bibRefCitation>
|
||
that, if premaxillary sacs (which are located between the premaxillary foramina and the anterior edge of the nares) were present in
|
||
<taxonomicName id="91D5FACEFF8EFA41F9C8FEA6B5E1EB16" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" box="[145,451,350,372]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="18" pageNumber="441" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8EFA41F9C8FEA6B5E1EB16" box="[145,451,350,372]" italics="true" pageId="18" pageNumber="441">Odobenocetops peruvianus</emphasis>
|
||
</taxonomicName>
|
||
, they were very reduced, probably vestigial. Therefore, and considering the reduced space on the dorsal face of the rostrum, it is highly probable that
|
||
<taxonomicName id="91D5FACEFF8EFA41F8DFFE43B60AEBB2" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" box="[390,552,443,464]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="18" pageNumber="441" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8EFA41F8DFFE43B60AEBB2" box="[390,552,443,464]" italics="true" pageId="18" pageNumber="441">O. peruvianus</emphasis>
|
||
</taxonomicName>
|
||
had no (or only a vestigial) melon. Although the nasal plugs, premaxillary sacs and melon are tightly related organs, the well-developed muscle scars for the insertion of the nasal plug muscle force us to conclude that
|
||
<taxonomicName id="91D5FACEFF8EFA41FBC0FDCEB4FFE80B" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="18" pageNumber="441" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8EFA41FBC0FDCEB4FFE80B" italics="true" pageId="18" pageNumber="441">O. peruvianus</emphasis>
|
||
</taxonomicName>
|
||
exhibited a strong reduction of the two latter organs but little reduction of the former.
|
||
</paragraph>
|
||
<paragraph id="566A814DFF8EFA41F9F0FD69B4CBE9D9" blockId="18.[145,761,197,955]" pageId="18" pageNumber="441">
|
||
On the anterior face of the snout the premaxillae bear several large foramina indicative of an extensive vascularization of the snout related to the inferred presence of a large and strong upper lip. The irregular surface of the bone in this region corresponds to the attachment of a very robust musculature of the lip. The morphology of the much better preserved female specimen of
|
||
<taxonomicName id="91D5FACEFF8EFA41F82FFC90B6DBE91C" authority="(SMNK PAL 2491)" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" box="[374,761,872,894]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="18" pageNumber="441" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8EFA41F82FFC90B63AE91F" box="[374,536,872,893]" italics="true" pageId="18" pageNumber="441">O. peruvianus</emphasis>
|
||
(SMNK PAL 2491)
|
||
</taxonomicName>
|
||
confirms the hypotheses based on the
|
||
<typeStatus id="896E3FEFFF8EFA41FB14FC7EB68CE9FE" box="[589,686,902,924]" pageId="18" pageNumber="441" type="holotype">holotype</typeStatus>
|
||
of the species.
|
||
</paragraph>
|
||
<paragraph id="566A814DFF8EFA41F86BFC0FB67AEE6C" blockId="18.[306,600,1015,1039]" box="[306,600,1015,1039]" pageId="18" pageNumber="441">MAXILLAE AND FRONTALS</paragraph>
|
||
<paragraph id="566A814DFF8EFA41F9C8FBD8B0DDE84E" blockId="18.[145,762,1056,1384]" lastBlockId="18.[809,1425,197,986]" pageId="18" pageNumber="441">
|
||
Posterior to the nares, between the mesethmoid and the maxillae, are two small triangular medial portions of the frontals, which have the same condition as the maxillae in relation to the premaxillae at the anterior region of the nares. In other words, the maxillae, which lay on the frontals, have withdrawn posterior to the nares, uncovering the frontals. Posteriorly, the medial portions of the frontals become thin and progressively disappear after the maxillae become joined. Further posteriorly, the medial edges of the maxillae separate again and uncover a thin strip of the frontals which widens posteriorly. On the
|
||
<typeStatus id="896E3FEFFF8EFA41FDF2FF3DB12EEAB9" box="[1195,1292,197,219]" pageId="18" pageNumber="441" type="holotype">holotype</typeStatus>
|
||
it is probable that the lower portion of the mesethmoid posterior to (and overhung by) the Y-shaped portion which separates the nares (see
|
||
<bibRefCitation id="3244FCBCFF8EFA41FD00FED9B148EB55" author="de Muizon C & Domning DP & Ketten DR" box="[1113,1386,289,311]" pageId="18" pageNumber="441" refId="ref23097" refString="de Muizon C, Domning DP, Ketten DR. 2002. Odobenocetops peruvianus, the walrus-convergent delphinoid (Cetacea, Mammalia) from the lower Pliocene of Peru. Smithsonian Contribution to Paleobiology 93: in press." type="book" year="2002">
|
||
de Muizon
|
||
<emphasis id="64A15D5FFF8EFA41FDBBFEDAB13AEB54" box="[1250,1304,289,311]" italics="true" pageId="18" pageNumber="441">et al</emphasis>
|
||
., 2002
|
||
</bibRefCitation>
|
||
) is in fact the medial portion of the frontal observed on the female skull fused to the mesethmoid. A medial portion of the frontal is clearly present in
|
||
<taxonomicName id="91D5FACEFF8EFA41FC57FE86B1B3EBF0" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[1294,1425,381,403]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="18" pageNumber="441" phylum="Chordata" rank="species" species="leptodon">
|
||
<emphasis id="64A15D5FFF8EFA41FC57FE86B1B3EBF0" box="[1294,1425,381,403]" italics="true" pageId="18" pageNumber="441">O. leptodon</emphasis>
|
||
</taxonomicName>
|
||
(MNHN SAO 202). The extensions of the maxillae posterior to the nares narrow posteriorly but are, like the premaxillae and tusks, relatively symmetrical, whereas in the male the right maxilla is wider and extends further posteriorly than the left.
|
||
</paragraph>
|
||
<paragraph id="566A814DFF8EFA41FA18FDCDB102E9B8" blockId="18.[809,1425,197,986]" pageId="18" pageNumber="441">
|
||
The preorbital process of the frontal of the female skull is anteriorly elongated and blade-like, as in the
|
||
<typeStatus id="896E3FEFFF8EFA41FA70FD8AB7AFE8EA" box="[809,909,626,648]" pageId="18" pageNumber="441" type="holotype">holotype</typeStatus>
|
||
. However, in this specimen it is clear that both the maxilla medially and the frontal laterally are components of the process. Therefore, although highly modified, the preorbital process of
|
||
<taxonomicName id="91D5FACEFF8EFA41FDBFFD37B1B2E886" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" box="[1254,1424,719,740]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="18" pageNumber="441" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8EFA41FDBFFD37B1B2E886" box="[1254,1424,719,740]" italics="true" pageId="18" pageNumber="441">O. peruvianus</emphasis>
|
||
</taxonomicName>
|
||
resembles that of the other odontocetes in the combined participation of the maxilla and frontal. The postorbital process is similar in shape to that of the
|
||
<typeStatus id="896E3FEFFF8EFA41FA70FCB1B7A8E93D" box="[809,906,841,863]" pageId="18" pageNumber="441" type="holotype">holotype</typeStatus>
|
||
but is larger and longer, indicating some individual variation of this character. A clear asymmetry of the frontal is present, as is observed in the other odontocetes, in which the right supraorbital process of the frontal is distinctly larger than the left.
|
||
</paragraph>
|
||
<paragraph id="566A814DFF8EFA41FAC0FBEEB103EE4F" blockId="18.[921,1313,1046,1070]" box="[921,1313,1046,1070]" pageId="18" pageNumber="441">PALATINE, PTERYGOID AND VOMER</paragraph>
|
||
<paragraph id="566A814DFF8EFA40FA70FBC6B5CFE9B8" blockId="18.[809,1426,1086,1384]" lastBlockId="19.[159,776,197,986]" lastPageId="19" lastPageNumber="442" pageId="18" pageNumber="441">
|
||
The vomer is very wide, the maxillae do not participate in the construction of the palate, and the premaxillae and the palatines have a large V-shaped suture on both sides as is observed in the
|
||
<typeStatus id="896E3FEFFF8EFA41FC70FB62B1AFEED2" box="[1321,1421,1178,1200]" pageId="18" pageNumber="441" type="holotype">holotype</typeStatus>
|
||
. The posterior region of the palate is perfectly preserved and adds to the knowledge of the species. In the posterior region of the palate, the medial edges of the palatines are in contact, hiding the vomer for a few centimetres of its length. Further posteriorly the palatines separate again, uncovering the vomer ventrally. The median ridge of the vomer projects about
|
||
<quantity id="912D2CA8FF8FFA40F9C6FF1CB4F0EA9B" box="[159,210,228,249]" metricMagnitude="-2" metricUnit="m" metricValue="7.0" pageId="19" pageNumber="442" unit="cm" value="7.0">7 cm</quantity>
|
||
posterior to the posterior edges of the palatines. The sutures with the pterygoids are widely separated. The apices of the pterygoid hamuli are sharply pointed and extend toward the anterior angle of the basioccipital crests formed by the medial laminae of the pterygoids. They are almost in contact on the right side and the anterior end of the left medial lamina is apparently broken. Because of this projection and the long nonpalatal ridge of the vomer, the palate of
|
||
<taxonomicName id="91D5FACEFF8FFA40FBB4FE22B53CE86F" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="19" pageNumber="442" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8FFA40FBB4FE22B53CE86F" italics="true" pageId="19" pageNumber="442">O. peruvianus</emphasis>
|
||
</taxonomicName>
|
||
is clearly shorter than in
|
||
<taxonomicName id="91D5FACEFF8FFA40FB09FE00B6F6E86F" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[592,724,504,525]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="19" pageNumber="442" phylum="Chordata" rank="species" species="leptodon">
|
||
<emphasis id="64A15D5FFF8FFA40FB09FE00B6F6E86F" box="[592,724,504,525]" italics="true" pageId="19" pageNumber="442">O. leptodon</emphasis>
|
||
</taxonomicName>
|
||
and its posterior border is strongly concave. The pterygoid hamulus is transversely compressed and the lateral lamina of the pterygoid almost contacts the medial lamina. Therefore, the fossa for the pterygoid sinus is extremely reduced (as observed by
|
||
<bibRefCitation id="3244FCBCFF8FFA40FB19FD69B4F4E8A7" author="de Muizon C & Domning DP & Ketten DR" pageId="19" pageNumber="442" refId="ref23097" refString="de Muizon C, Domning DP, Ketten DR. 2002. Odobenocetops peruvianus, the walrus-convergent delphinoid (Cetacea, Mammalia) from the lower Pliocene of Peru. Smithsonian Contribution to Paleobiology 93: in press." type="book" year="2002">
|
||
de Muizon
|
||
<emphasis id="64A15D5FFF8FFA40FB9CFD6AB6DBE8C4" box="[709,761,657,679]" italics="true" pageId="19" pageNumber="442">et al</emphasis>
|
||
., 2002
|
||
</bibRefCitation>
|
||
on the
|
||
<typeStatus id="896E3FEFFF8FFA40F868FD48B5B1E8A4" box="[305,403,688,710]" pageId="19" pageNumber="442" type="holotype">holotype</typeStatus>
|
||
) and hardly present in
|
||
<taxonomicName id="91D5FACEFF8FFA40FBF0FD48B4C9E886" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="19" pageNumber="442" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8FFA40FBF0FD48B4C9E886" italics="true" pageId="19" pageNumber="442">O. peruvianus</emphasis>
|
||
</taxonomicName>
|
||
. It is clearly more reduced than in
|
||
<taxonomicName id="91D5FACEFF8FFA40FB27FD37B722E881" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[638,768,718,740]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="19" pageNumber="442" phylum="Chordata" rank="species" species="leptodon">
|
||
<emphasis id="64A15D5FFF8FFA40FB27FD37B722E881" box="[638,768,718,740]" italics="true" pageId="19" pageNumber="442">O. leptodon</emphasis>
|
||
</taxonomicName>
|
||
, in which the fossa is very small but conspicuous. As in
|
||
<taxonomicName id="91D5FACEFF8FFA40F9E7FCF4B563E943" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[190,321,780,801]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="19" pageNumber="442" phylum="Chordata" rank="species" species="leptodon">
|
||
<emphasis id="64A15D5FFF8FFA40F9E7FCF4B563E943" box="[190,321,780,801]" italics="true" pageId="19" pageNumber="442">O. leptodon</emphasis>
|
||
</taxonomicName>
|
||
, there is a short but continuous lateral lamina of the pterygoid, which contacts the alisphenoid, contrary to the condition in Recent delphinoids. However, in Recent monodontids, a continuous lateral lamina of the pterygoid, although almost absent from the pterygoid hamulus, is sometimes present and contacts the squamosal dorsally.
|
||
</paragraph>
|
||
<caption id="02AAD1C5FF8EFA41F9C8F8C6B5E5ED13" ID-DOI="http://doi.org/10.5281/zenodo.4687213" ID-Zenodo-Dep="4687213" httpUri="https://zenodo.org/record/4687213/files/figure.png" pageId="18" pageNumber="441" startId="18.[145,224,1854,1875]" targetBox="[157,1410,1469,1821]" targetPageId="18">
|
||
<paragraph id="566A814DFF8EFA41F9C8F8C6B5E5ED13" blockId="18.[145,1425,1854,1905]" pageId="18" pageNumber="441">
|
||
<emphasis id="64A15D5FFF8EFA41F9C8F8C6B52AED31" bold="true" box="[145,264,1854,1875]" pageId="18" pageNumber="441">Figure 14.</emphasis>
|
||
<taxonomicName id="91D5FACEFF8EFA41F84AF8C6B60BED31" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" box="[275,553,1854,1875]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="18" pageNumber="441" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8EFA41F84AF8C6B60BED31" box="[275,553,1854,1875]" italics="true" pageId="18" pageNumber="441">Odobenocetops peruvianus</emphasis>
|
||
</taxonomicName>
|
||
, referred specimen (SMNK PAL 2491). Skull of a probable female in lateral right (A) and lateral left (B) views.
|
||
</paragraph>
|
||
</caption>
|
||
<paragraph id="566A814DFF8FFA40F8DFFBEEB602EE4C" blockId="19.[390,544,1046,1070]" box="[390,544,1046,1070]" pageId="19" pageNumber="442">ALISPHENOID</paragraph>
|
||
<paragraph id="566A814DFF8FFA40F9C6FBC6B55DEC60" blockId="19.[159,775,1086,1538]" pageId="19" pageNumber="442">
|
||
The alisphenoid is similar to that of
|
||
<taxonomicName id="91D5FACEFF8FFA40FB1FFBC7B6EBEE31" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[582,713,1086,1108]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="19" pageNumber="442" phylum="Chordata" rank="species" species="leptodon">
|
||
<emphasis id="64A15D5FFF8FFA40FB1FFBC7B6EBEE31" box="[582,713,1086,1108]" italics="true" pageId="19" pageNumber="442">O. leptodon</emphasis>
|
||
</taxonomicName>
|
||
. It is very thick and bears an enormous foramen ovale not confluent with the cranial hiatus.
|
||
<bibRefCitation id="3244FCBCFF8FFA40FB19FB84B4C4EED3" author="de Muizon C & Domning DP & Ketten DR" pageId="19" pageNumber="442" refId="ref23097" refString="de Muizon C, Domning DP, Ketten DR. 2002. Odobenocetops peruvianus, the walrus-convergent delphinoid (Cetacea, Mammalia) from the lower Pliocene of Peru. Smithsonian Contribution to Paleobiology 93: in press." type="book" year="2002">
|
||
de Muizon
|
||
<emphasis id="64A15D5FFF8FFA40FB90FB85B722EEF3" box="[713,768,1148,1170]" italics="true" pageId="19" pageNumber="442">et al</emphasis>
|
||
. (2002)
|
||
</bibRefCitation>
|
||
stated that in the
|
||
<typeStatus id="896E3FEFFF8FFA40F8E0FB62B638EED2" box="[441,538,1178,1200]" pageId="19" pageNumber="442" type="holotype">holotype</typeStatus>
|
||
of
|
||
<taxonomicName id="91D5FACEFF8FFA40FB65FB63B6F9EED2" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" box="[572,731,1179,1200]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="19" pageNumber="442" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8FFA40FB65FB63B6F9EED2" box="[572,731,1179,1200]" italics="true" pageId="19" pageNumber="442">O. peruvianus</emphasis>
|
||
</taxonomicName>
|
||
the foramen ovale was confluent with the cranial hiatus. Because this is not the case in the three other skulls referred to
|
||
<taxonomicName id="91D5FACEFF8FFA40F87BFB0EB5EBEF69" authorityName="PERUVIANUS MUIZON" authorityYear="1993" box="[290,457,1270,1291]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="19" pageNumber="442" phylum="Chordata" rank="genus">
|
||
<emphasis id="64A15D5FFF8FFA40F87BFB0EB5EBEF69" box="[290,457,1270,1291]" italics="true" pageId="19" pageNumber="442">Odobenocetops</emphasis>
|
||
</taxonomicName>
|
||
, it is possible that the condition observed in the
|
||
<typeStatus id="896E3FEFFF8FFA40F8C5FAEDB5DFEF49" box="[412,509,1301,1323]" pageId="19" pageNumber="442" type="holotype">holotype</typeStatus>
|
||
is due to a postmortem breakage of the alisphenoid. As in
|
||
<taxonomicName id="91D5FACEFF8FFA40FB14FACCB6F7EF2B" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[589,725,1332,1353]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="19" pageNumber="442" phylum="Chordata" rank="species" species="leptodon">
|
||
<emphasis id="64A15D5FFF8FFA40FB14FACCB6F7EF2B" box="[589,725,1332,1353]" italics="true" pageId="19" pageNumber="442">O. leptodon</emphasis>
|
||
</taxonomicName>
|
||
the external opening of the foramen ovale is formed anteriorly by the pterygoid and posteriorly by the alisphenoid. Internally, the foramen ovale is fully enclosed in the alisphenoid. It is noteworthy, however, that this condition is not easy to observe because of the partial fusion of the bones.
|
||
</paragraph>
|
||
<caption id="02AAD1C5FF8FFA40FA6EFB9EB000EFE1" ID-DOI="http://doi.org/10.5281/zenodo.4687217" ID-Zenodo-Dep="4687217" httpUri="https://zenodo.org/record/4687217/files/figure.png" pageId="19" pageNumber="442" startId="19.[823,902,1126,1147]" targetBox="[828,1436,197,1094]" targetPageId="19">
|
||
<paragraph id="566A814DFF8FFA40FA6EFB9EB000EFE1" blockId="19.[823,1439,1126,1411]" pageId="19" pageNumber="442">
|
||
<emphasis id="64A15D5FFF8FFA40FA6EFB9EB78CEE19" bold="true" box="[823,942,1126,1147]" pageId="19" pageNumber="442">Figure 15.</emphasis>
|
||
Auditory region of
|
||
<taxonomicName id="91D5FACEFF8FFA40FDDAFB9EB1BBEE19" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" box="[1155,1433,1126,1147]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="19" pageNumber="442" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF8FFA40FDDAFB9EB1BBEE19" box="[1155,1433,1126,1147]" italics="true" pageId="19" pageNumber="442">Odobenocetops peruvianus</emphasis>
|
||
</taxonomicName>
|
||
, holotype (SMNK PAL 2491). Lateral view (A) and posterolateral view showing the tympanic aperture (B). On B, the outline of the tympanic aperture has been enhanced with a white line. Abbreviations: Ap, anterior process of the periotic; Bo, basioccipital; Eam, external auditory meatus; Fo, foramen ovale; Gf, glenoid fossa; Oc, occipital condyle; Po, paroccipital process of the exoccipital; Ptp, post-tympanic process of the squamosal; Sp, sigmoid process of the tympanic; Tym, tympanic.
|
||
</paragraph>
|
||
</caption>
|
||
<paragraph id="566A814DFF8FFA40F876F9C6B654EC37" blockId="19.[303,630,1598,1622]" box="[303,630,1598,1622]" pageId="19" pageNumber="442">SQUAMOSAL AND EAR BONES</paragraph>
|
||
<paragraph id="566A814DFF8FFA47F9C6F99EB543EA98" blockId="19.[159,776,1638,1906]" lastBlockId="20.[145,761,197,1906]" lastPageId="20" lastPageNumber="443" pageId="19" pageNumber="442">
|
||
The squamosal of SMNK PAL 2491 is basically similar to that of the
|
||
<typeStatus id="896E3FEFFF8FFA40F864F97DB583ECF9" box="[317,417,1669,1691]" pageId="19" pageNumber="442" type="holotype">holotype</typeStatus>
|
||
. The tympanic and the periotic are preserved
|
||
<emphasis id="64A15D5FFF8FFA40F813F95CB5BAECDB" box="[330,408,1700,1721]" italics="true" pageId="19" pageNumber="442">in situ</emphasis>
|
||
on both sides of the specimen (
|
||
<figureCitation id="CEEE9DC8FF8FFA40F9FEF93AB4D8ECBA" box="[167,250,1730,1752]" captionStart="Figure 15" captionStartId="19.[823,902,1126,1147]" captionTargetBox="[828,1436,197,1094]" captionTargetId="figure-601@19.[828,1436,197,1094]" captionTargetPageId="19" captionText="Figure 15. Auditory region of Odobenocetops peruvianus, holotype (SMNK PAL 2491). Lateral view (A) and posterolateral view showing the tympanic aperture (B). On B, the outline of the tympanic aperture has been enhanced with a white line.Abbreviations:Ap, anterior process of the periotic; Bo, basioccipital; Eam, external auditory meatus; Fo, foramen ovale; Gf, glenoid fossa; Oc, occipital condyle; Po, paroccipital process of the exoccipital; Ptp, post-tympanic process of the squamosal; Sp, sigmoid process of the tympanic; Tym, tympanic." figureDoi="http://doi.org/10.5281/zenodo.4687217" httpUri="https://zenodo.org/record/4687217/files/figure.png" pageId="19" pageNumber="442">Fig. 15</figureCitation>
|
||
). Since the bones could not be removed from the skull it is not possible to describe them thoroughly. However, it is clear that they are extremely similar to those referred to the species by
|
||
<bibRefCitation id="3244FCBCFF8FFA40FB58F8E6B726ED57" author="de Muizon C & Domning DP & Ketten DR" box="[513,772,1822,1845]" pageId="19" pageNumber="442" refId="ref23097" refString="de Muizon C, Domning DP, Ketten DR. 2002. Odobenocetops peruvianus, the walrus-convergent delphinoid (Cetacea, Mammalia) from the lower Pliocene of Peru. Smithsonian Contribution to Paleobiology 93: in press." type="book" year="2002">
|
||
de Muizon
|
||
<emphasis id="64A15D5FFF8FFA40FB25F8E7B68EED51" box="[636,684,1822,1844]" italics="true" pageId="19" pageNumber="442">et al</emphasis>
|
||
. (2002)
|
||
</bibRefCitation>
|
||
. The lateral face of the tympanic bears a large sigmoid process which is grossly perpendicular to the anteroposterior axis of the bone and not shifted posteriorly as in the classical (i.e. non-odobenocetopsid) delphinoids. The apex of the process is straight, rounded, and not strongly recurved anteriorly as is observed in the classical delphinoids. Posterior to it is a low conical process and a relatively large anterior border of the posterior process. These three elements surround the external auditory meatus and, as a consequence of their morphology, the meatus is much larger than in the classical delphinoids. It is slightly smaller than in
|
||
<taxonomicName id="91D5FACEFF8FFA40FA6EF8E7B082ED56" authority="(SMNK PAL 2492)" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[823,1184,1822,1844]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="19" pageNumber="442" phylum="Chordata" rank="species" species="leptodon">
|
||
<emphasis id="64A15D5FFF8FFA40FA6EF8E7B799ED51" box="[823,955,1822,1844]" italics="true" pageId="19" pageNumber="442">O. leptodon</emphasis>
|
||
(SMNK PAL 2492)
|
||
</taxonomicName>
|
||
. This condition would indicate a more efficient (effective) tympanic membrane in the
|
||
<taxonomicName id="91D5FACEFF8FFA40FA9CF8A4B0BDED10" authorityName="MUIZON" authorityYear="1993" box="[965,1183,1884,1906]" class="Mammalia" family="Odobenocetopsidae" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="19" pageNumber="442" phylum="Chordata" rank="family">Odobenocetopsidae</taxonomicName>
|
||
and therefore possibly better sound perception via the middle ear than in the other odontocetes.
|
||
</paragraph>
|
||
<paragraph id="566A814DFF88FA47F9F0FEFAB58FE829" blockId="20.[145,761,197,1906]" pageId="20" pageNumber="443">
|
||
The lateral wall of the tympanic is high, as is observed in
|
||
<taxonomicName id="91D5FACEFF88FA47F845FEDAB5BDEB54" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[284,415,289,311]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="species" species="leptodon">
|
||
<emphasis id="64A15D5FFF88FA47F845FEDAB5BDEB54" box="[284,415,289,311]" italics="true" pageId="20" pageNumber="443">O. leptodon</emphasis>
|
||
</taxonomicName>
|
||
. This condition indicates that the middle ear cavity was larger than in the classical delphinoids. It resembles the condition of most early diverging odontocetes (
|
||
<taxonomicName id="91D5FACEFF88FA47F8EAFE85B64AEBF1" authorityName="Brandt" authorityYear="1873" box="[435,616,381,403]" class="Mammalia" family="Squalodontidae" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="family">Squalodontidae</taxonomicName>
|
||
,
|
||
<taxonomicName id="91D5FACEFF88FA47FBD9FE85B4DAEBD0" baseAuthorityName="Dal Piaz" baseAuthorityYear="1917" class="Mammalia" family="Squalodelphinidae" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="family">Squalodelphinidae</taxonomicName>
|
||
,
|
||
<taxonomicName id="91D5FACEFF88FA47F848FE64B58FEBD0" authorityName="J.E.Gray" authorityYear="1846" box="[273,429,412,434]" class="Mammalia" family="Platanistidae" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="family">Platanistidae</taxonomicName>
|
||
,
|
||
<taxonomicName id="91D5FACEFF88FA47F89FFE64B68CEBD0" baseAuthorityName="Abel" baseAuthorityYear="1901" box="[454,686,412,434]" class="Mammalia" family="Eurhinodelphinidae" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="family">Eurhinodelphinidae</taxonomicName>
|
||
), and could represent a plesiomorphic condition or, more likely, a reversal corresponding to a need for enlargement of the middle ear cavity. The anterior extremity of the tympanic is blunt and rounded, as is observed in the other delphinoids.
|
||
</paragraph>
|
||
<paragraph id="566A814DFF88FA47F9F0FDACB6A1E99A" blockId="20.[145,761,197,1906]" pageId="20" pageNumber="443">
|
||
The ventral lobes are well separated by a deep median groove which is well-marked on the posterior two-thirds of the bone. Their posterior extremities are rounded and wide and the medial lobe is slightly posterior to the lateral. This condition is similar to that of
|
||
<taxonomicName id="91D5FACEFF88FA47F9BCFD15B54AE960" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[229,360,749,770]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="species" species="leptodon">
|
||
<emphasis id="64A15D5FFF88FA47F9BCFD15B54AE960" box="[229,360,749,770]" italics="true" pageId="20" pageNumber="443">O. leptodon</emphasis>
|
||
</taxonomicName>
|
||
but clearly differs from that of the Recent monodontids, in which the posterior extremity of the medial lobe is narrower and more anterior than that of the lateral lobe. This feature is especially obvious in
|
||
<taxonomicName id="91D5FACEFF88FA47F840FC90B5A0E91F" baseAuthorityName="Howell" baseAuthorityYear="1930" box="[281,386,872,893]" class="Mammalia" family="Monodontidae" genus="Monodon" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="genus">
|
||
<emphasis id="64A15D5FFF88FA47F840FC90B5A0E91F" box="[281,386,872,893]" italics="true" pageId="20" pageNumber="443">Monodon</emphasis>
|
||
</taxonomicName>
|
||
. It is also present to a lesser extent in the delphinids and phocoenids. Again, the odobenocetopsid condition is found in the early diverging odontocetes mentioned above, but is regarded here as a reversal (rather than a plesiomorphy).
|
||
</paragraph>
|
||
<paragraph id="566A814DFF88FA47F9F0FBFAB033EB34" blockId="20.[145,761,197,1906]" lastBlockId="20.[809,1425,197,832]" pageId="20" pageNumber="443">
|
||
Not much can be said about the periotic, which is preserved
|
||
<emphasis id="64A15D5FFF88FA47F849FBD8B540EE57" box="[272,354,1056,1077]" italics="true" pageId="20" pageNumber="443">in situ</emphasis>
|
||
, except that it has the massive morphology observed on the referred specimens described by
|
||
<bibRefCitation id="3244FCBCFF88FA47F87CFBA5B609EE11" author="de Muizon C & Domning DP & Ketten DR" box="[293,555,1117,1139]" pageId="20" pageNumber="443" refId="ref23097" refString="de Muizon C, Domning DP, Ketten DR. 2002. Odobenocetops peruvianus, the walrus-convergent delphinoid (Cetacea, Mammalia) from the lower Pliocene of Peru. Smithsonian Contribution to Paleobiology 93: in press." type="book" year="2002">
|
||
de Muizon
|
||
<emphasis id="64A15D5FFF88FA47F8FBFBA6B5F0EE10" box="[418,466,1117,1139]" italics="true" pageId="20" pageNumber="443">et al</emphasis>
|
||
. (2002)
|
||
</bibRefCitation>
|
||
. Contrary to what is observed in the classical delphinoids, the lateral portion of the bone is closely appressed against the squamosal, in this respect resembling the condition observed in the platanistoids (
|
||
<emphasis id="64A15D5FFF88FA47F8B7FB20B60FEE8F" box="[494,557,1240,1261]" italics="true" pageId="20" pageNumber="443">sensu</emphasis>
|
||
<bibRefCitation id="3244FCBCFF88FA47FB6DFB20B6D6EE8F" author="de Muizon C" box="[564,756,1240,1262]" pageId="20" pageNumber="443" pagination="1 - 27" refId="ref22726" refString="de Muizon C. 1987. The affinities of Notocetus vanbenedeni, an early Miocene platanistoid (Cetacea, Mammalia) from Patagonia, southern Argentina. American Museum Novitates 2904: 1 - 27." type="journal article" year="1987">de Muizon, 1987</bibRefCitation>
|
||
;
|
||
<bibRefCitation id="3244FCBCFF88FA47F9C8FB0FB4E8EF6E" author="de Muizon C" box="[145,202,1271,1292]" pageId="20" pageNumber="443" pagination="279 - 326" refId="ref22826" refString="de Muizon C. 1991. A new ziphiid (Odontoceti, Mammalia) from the Early Miocene of Washington state (USA) and a phylogenetical analysis of the major groups of odontocetes. Bulletin du Museum national d'Histoire naturelle, 4 e ser., Sect. C 12: 279 - 326." type="journal article" year="1991">1991</bibRefCitation>
|
||
;
|
||
<bibRefCitation id="3244FCBCFF88FA47F980FB0FB530EF6E" author="de Muizon C" box="[217,274,1271,1292]" pageId="20" pageNumber="443" pagination="135 - 146" refId="ref22938" refString="de Muizon C. 1994. Are the squalodonts related to the platanistoids? In: Berta A, Demere TA, eds. Contributions in Marine Mammalogy Honoring Frank C. Whitmore Jr. Proceedings of the San Diego Society of Natural History 29: 135 - 146." type="journal article" year="1994">1994</bibRefCitation>
|
||
; Fordyce & Barnes, 1994; Fordyce
|
||
<emphasis id="64A15D5FFF88FA47FBEFFB0FB6C9EF69" box="[694,747,1270,1292]" italics="true" pageId="20" pageNumber="443">et al</emphasis>
|
||
., 1994; Fordyce, 1994; not sensu
|
||
<bibRefCitation id="3244FCBCFF88FA47FB7AFAEEB4E9EF28" author="McKenna MC & Bell SK" pageId="20" pageNumber="443" refId="ref22556" refString="McKenna MC, Bell SK. 1997. Classification of Mammals Above the Species Level. New York: Columbia University Press." type="book" year="1997">McKenna & Bell, 1997</bibRefCitation>
|
||
). Furthermore, the posterior process of the periotic is deeply wedged between the squamosal and the exoccipital, which is in agreement with the long posterior process observed on MNHN SAS 1614 (an isolated periotic from the same horizon as the
|
||
<typeStatus id="896E3FEFFF88FA47FBC1FA56B6DBEFA6" box="[664,761,1454,1476]" pageId="20" pageNumber="443" type="holotype">holotype</typeStatus>
|
||
of
|
||
<taxonomicName id="91D5FACEFF88FA47F9E3FA35B54AEF81" baseAuthorityName="SMNK PAL" baseAuthorityYear="2491" box="[186,360,1485,1507]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF88FA47F9E3FA35B54AEF81" box="[186,360,1485,1507]" italics="true" pageId="20" pageNumber="443">O. peruvianus</emphasis>
|
||
</taxonomicName>
|
||
and referred to this species). A similar condition is present in
|
||
<taxonomicName id="91D5FACEFF88FA47FB10FA14B519EC43" authority="(Kasuya, 1973)" baseAuthorityName="Kasuya" baseAuthorityYear="1973" class="Mammalia" family="Monodontidae" genus="Delphinapterus" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="genus">
|
||
<emphasis id="64A15D5FFF88FA47FB10FA14B6DBEC63" box="[585,761,1516,1537]" italics="true" pageId="20" pageNumber="443">Delphinapterus</emphasis>
|
||
(
|
||
<bibRefCitation id="3244FCBCFF88FA47F9C0F9F3B511EC43" author="Kasuya T" box="[153,307,1547,1569]" pageId="20" pageNumber="443" pagination="1 - 103" refId="ref22390" refString="Kasuya T. 1973. Systematic consideration of Recent toothed whales based on the morphology of the tympano-periotic bone. Scientific Reports of the Whales Research Institute 25: 1 - 103." type="journal article" year="1973">Kasuya, 1973</bibRefCitation>
|
||
)
|
||
</taxonomicName>
|
||
and
|
||
<taxonomicName id="91D5FACEFF88FA47F828F9F2B5F8EC7D" baseAuthorityName="Howell" baseAuthorityYear="1930" box="[369,474,1546,1567]" class="Mammalia" family="Monodontidae" genus="Monodon" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="genus">
|
||
<emphasis id="64A15D5FFF88FA47F828F9F2B5F8EC7D" box="[369,474,1546,1567]" italics="true" pageId="20" pageNumber="443">Monodon</emphasis>
|
||
</taxonomicName>
|
||
. The delphinids and phocoenids are characterized by a petrotympanic completely isolated from the skull and maintained
|
||
<emphasis id="64A15D5FFF88FA47FBF6F9B0B6DBEC3F" box="[687,761,1608,1629]" italics="true" pageId="20" pageNumber="443">in situ</emphasis>
|
||
by ligaments only (
|
||
<bibRefCitation id="3244FCBCFF88FA47F8D8F99FB6BDEC1E" author="Fraser FC & Purves PE" box="[385,671,1638,1660]" pageId="20" pageNumber="443" pagination="1 - 140" refId="ref22111" refString="Fraser FC, Purves PE. 1960. Hearing in cetaceans: evolution of the accessory air sacs and the structure and function of the outer and middle ear in recent cetaceans. Bulletin of the British Museum of Natural History (Zoology) 7: 1 - 140." type="journal article" year="1960">Fraser & Purves, 1960</bibRefCitation>
|
||
). Early derived odontocetes such as platanistoids have a tympanic and a periotic still articulated with the squamosal, which is regarded as a plesiomophic character state (
|
||
<bibRefCitation id="3244FCBCFF88FA47F844F919B5FDEC94" author="de Muizon C" box="[285,479,1761,1783]" pageId="20" pageNumber="443" pagination="1 - 27" refId="ref22726" refString="de Muizon C. 1987. The affinities of Notocetus vanbenedeni, an early Miocene platanistoid (Cetacea, Mammalia) from Patagonia, southern Argentina. American Museum Novitates 2904: 1 - 27." type="journal article" year="1987">de Muizon, 1987</bibRefCitation>
|
||
;
|
||
<bibRefCitation id="3244FCBCFF88FA47F8B4F919B604EC94" author="de Muizon C" box="[493,550,1761,1782]" pageId="20" pageNumber="443" pagination="279 - 326" refId="ref22826" refString="de Muizon C. 1991. A new ziphiid (Odontoceti, Mammalia) from the Early Miocene of Washington state (USA) and a phylogenetical analysis of the major groups of odontocetes. Bulletin du Museum national d'Histoire naturelle, 4 e ser., Sect. C 12: 279 - 326." type="journal article" year="1991">1991</bibRefCitation>
|
||
;
|
||
<bibRefCitation id="3244FCBCFF88FA47FB6DF919B64CEC95" author="de Muizon C" box="[564,622,1761,1783]" pageId="20" pageNumber="443" pagination="135 - 146" refId="ref22938" refString="de Muizon C. 1994. Are the squalodonts related to the platanistoids? In: Berta A, Demere TA, eds. Contributions in Marine Mammalogy Honoring Frank C. Whitmore Jr. Proceedings of the San Diego Society of Natural History 29: 135 - 146." type="journal article" year="1994">1994</bibRefCitation>
|
||
). Therefore, the condition of
|
||
<taxonomicName id="91D5FACEFF88FA47F813F8F8B5D3ED77" authorityName="PERUVIANUS MUIZON" authorityYear="1993" box="[330,497,1792,1813]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="genus">
|
||
<emphasis id="64A15D5FFF88FA47F813F8F8B5D3ED77" box="[330,497,1792,1813]" italics="true" pageId="20" pageNumber="443">Odobenocetops</emphasis>
|
||
</taxonomicName>
|
||
and the
|
||
<taxonomicName id="91D5FACEFF88FA47FB0EF8F8B6DBED74" baseAuthorityName="de Muizon" baseAuthorityYear="1988" box="[599,761,1792,1814]" class="Mammalia" family="Monodontidae" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="family">Monodontidae</taxonomicName>
|
||
could be regarded as plesiomorphic. However, because they have synapomorphies of the
|
||
<taxonomicName id="91D5FACEFF88FA47FB56F8C5B685ED31" box="[527,679,1853,1875]" pageId="20" pageNumber="424" rank="superFamily" superFamily="Delphinoidea">Delphinoidea</taxonomicName>
|
||
absent in the Platanistoidea, we rather consider the condition of
|
||
<taxonomicName id="91D5FACEFF88FA47FA10FF3DB7D2EAB8" authorityName="PERUVIANUS MUIZON" authorityYear="1993" box="[841,1008,197,218]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="genus">
|
||
<emphasis id="64A15D5FFF88FA47FA10FF3DB7D2EAB8" box="[841,1008,197,218]" italics="true" pageId="20" pageNumber="443">Odobenocetops</emphasis>
|
||
</taxonomicName>
|
||
as a reversal due to its hyperspecialization. The fact that a condition approaching this one is also found in monodontids could represent a synapomorphy of the two families, possibly related to sound transmission.
|
||
</paragraph>
|
||
<paragraph id="566A814DFF88FA47FA18FEA7B0D3E8EA" blockId="20.[809,1425,197,832]" pageId="20" pageNumber="443">
|
||
In general, the periotic and tympanic of
|
||
<taxonomicName id="91D5FACEFF88FA47FC49FEA6B775EBF1" authorityName="PERUVIANUS MUIZON" authorityYear="1993" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="genus">
|
||
<emphasis id="64A15D5FFF88FA47FC49FEA6B775EBF1" italics="true" pageId="20" pageNumber="443">Odobenocetops</emphasis>
|
||
</taxonomicName>
|
||
have relatively tight and extensive contacts with the surrounding bones: basioccipital and squamosal for the tympanic, and squamosal and exoccipital for the periotic. The lateral tuberosity and rim of the anterior process of the periotic are closely appressed against the squamosal in a similar pattern to that observed in the platanistoids. The squamosal in this region is greatly thickened and forms the medial border of the trough-like glenoid cavity.
|
||
</paragraph>
|
||
<paragraph id="566A814DFF88FA47FA18FD69B785E922" blockId="20.[809,1425,197,832]" pageId="20" pageNumber="443">
|
||
On the anterior region of the anterior process of the periotic are several independent bony nodules which are appressed against the anterior process and apparently part of it. Such a condition has been observed in
|
||
<taxonomicName id="91D5FACEFF88FA47FA09FCF4B7FEE943" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[848,988,780,801]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="species" species="leptodon">
|
||
<emphasis id="64A15D5FFF88FA47FA09FCF4B7FEE943" box="[848,988,780,801]" italics="true" pageId="20" pageNumber="443">O. leptodon</emphasis>
|
||
</taxonomicName>
|
||
and is also present sometimes in
|
||
<taxonomicName id="91D5FACEFF88FA47FA70FCD2B782E95D" box="[809,928,810,831]" class="Mammalia" family="Platanistidae" genus="Platanista" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="genus">
|
||
<emphasis id="64A15D5FFF88FA47FA70FCD2B782E95D" box="[809,928,810,831]" italics="true" pageId="20" pageNumber="443">Platanista</emphasis>
|
||
</taxonomicName>
|
||
.
|
||
</paragraph>
|
||
<paragraph id="566A814DFF88FA47FD51FC85B093E9F7" blockId="20.[1032,1201,893,917]" box="[1032,1201,893,917]" pageId="20" pageNumber="443">BASIOCCIPITAL</paragraph>
|
||
<paragraph id="566A814DFF88FA47FA70FC5DB791EEF3" blockId="20.[809,1426,933,1169]" pageId="20" pageNumber="443">
|
||
The basioccipital is extremely wide and basically similar to that of
|
||
<taxonomicName id="91D5FACEFF88FA47FAACFC3CB05AE9BB" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[1013,1144,964,985]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="species" species="leptodon">
|
||
<emphasis id="64A15D5FFF88FA47FAACFC3CB05AE9BB" box="[1013,1144,964,985]" italics="true" pageId="20" pageNumber="443">O. leptodon</emphasis>
|
||
</taxonomicName>
|
||
although slightly wider. The basioccipital crests are large and undergird the tympanics, which are partially imbedded in their lateral face. The posteromedial faces of the basioccipital crests bear very large and deep muscular scars for insertion of the scalenus, at least as strong as in
|
||
<taxonomicName id="91D5FACEFF88FA47FA70FB84B78EEEF3" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[809,940,1148,1169]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="species" species="leptodon">
|
||
<emphasis id="64A15D5FFF88FA47FA70FB84B78EEEF3" box="[809,940,1148,1169]" italics="true" pageId="20" pageNumber="443">O. leptodon</emphasis>
|
||
</taxonomicName>
|
||
.
|
||
</paragraph>
|
||
<paragraph id="566A814DFF88FA47FD4AFB36B085EE84" blockId="20.[1043,1191,1230,1254]" box="[1043,1191,1230,1254]" pageId="20" pageNumber="443">EXOCCIPITAL</paragraph>
|
||
<paragraph id="566A814DFF88FA46FA70FB0EB629EB17" blockId="20.[809,1425,1270,1906]" lastBlockId="21.[159,776,197,710]" lastPageId="21" lastPageNumber="444" pageId="20" pageNumber="443">
|
||
The paroccipital process is very large and stout. It differs from that of the
|
||
<typeStatus id="896E3FEFFF88FA47FD1FFAEDB085EF49" box="[1094,1191,1301,1323]" pageId="20" pageNumber="443" type="holotype">holotype</typeStatus>
|
||
in being orientated ventrally and not ventrolaterally. Its ventromedial angle contacts the posteroventral angle of the basioccipital crest and encloses the jugular notch to form a relatively large window, as is observed in
|
||
<taxonomicName id="91D5FACEFF88FA47FC51FA68B1A8EFC7" baseAuthorityName="SMNK PAL" baseAuthorityYear="2492" box="[1288,1418,1424,1445]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="species" species="leptodon">
|
||
<emphasis id="64A15D5FFF88FA47FC51FA68B1A8EFC7" box="[1288,1418,1424,1445]" italics="true" pageId="20" pageNumber="443">O. leptodon</emphasis>
|
||
</taxonomicName>
|
||
. The exoccipital border of the window is very thick and forms an elevated crest. This indicates a strong scalenus dorsalis, which is inserted on the posteroventral face of the paroccipital process. This part of the occipital indicates an exceptionally strong musculature of the neck as was noted in regard to the
|
||
<typeStatus id="896E3FEFFF88FA47FC00F9B0B778EC1E" pageId="20" pageNumber="443" type="holotype">holotype</typeStatus>
|
||
of
|
||
<taxonomicName id="91D5FACEFF88FA47FADDF99EB74EECF9" authority="(de Muizon et al., 2002)" baseAuthorityName="de Muizon" baseAuthorityYear="2002" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="20" pageNumber="443" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF88FA47FADDF99EB097EC1E" box="[900,1205,1638,1660]" italics="true" pageId="20" pageNumber="443">Odobenocetops peruvianus</emphasis>
|
||
(
|
||
<bibRefCitation id="3244FCBCFF88FA47FD91F99EB746ECF9" author="de Muizon C & Domning DP & Ketten DR" pageId="20" pageNumber="443" refId="ref23097" refString="de Muizon C, Domning DP, Ketten DR. 2002. Odobenocetops peruvianus, the walrus-convergent delphinoid (Cetacea, Mammalia) from the lower Pliocene of Peru. Smithsonian Contribution to Paleobiology 93: in press." type="book" year="2002">
|
||
de Muizon
|
||
<emphasis id="64A15D5FFF88FA47FC17F99FB1A1EC19" box="[1358,1411,1638,1660]" italics="true" pageId="20" pageNumber="443">et al</emphasis>
|
||
., 2002
|
||
</bibRefCitation>
|
||
)
|
||
</taxonomicName>
|
||
. The anterior face of the paroccipital process does not present any fossa for the posterior sinus such as is observed in many other delphinoids.
|
||
<bibRefCitation id="3244FCBCFF88FA47FC7FF93BB7EAEC95" author="Fraser FC & Purves PE" pageId="20" pageNumber="443" pagination="1 - 140" refId="ref22111" refString="Fraser FC, Purves PE. 1960. Hearing in cetaceans: evolution of the accessory air sacs and the structure and function of the outer and middle ear in recent cetaceans. Bulletin of the British Museum of Natural History (Zoology) 7: 1 - 140." type="journal article" year="1960">Fraser & Purves (1960)</bibRefCitation>
|
||
have stated that the absence of a fossa is not equivalent to absence of a posterior sinus. As a matter of fact, in the Recent monodontids the anterior face of the paroccipital process is not excavated by a fossa and a small posterior sinus is present. However, the presence of a large sinus is related to a deep fossa. In SMNK PAL 2491 the anterior face of the paroccipital process has a reduced area and is not indicative of a large posterior sinus. This statement contrasts with the observations made on the
|
||
<typeStatus id="896E3FEFFF89FA46FB73FEB8B6A9EB34" box="[554,651,320,342]" pageId="21" pageNumber="444" type="holotype">holotype</typeStatus>
|
||
of
|
||
<taxonomicName id="91D5FACEFF89FA46FBF2FEB8B625EB17" authority="(de Muizon et al., 2002)" baseAuthorityName="de Muizon" baseAuthorityYear="2002" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="21" pageNumber="444" phylum="Chordata" rank="species" species="peruvianus">
|
||
<emphasis id="64A15D5FFF89FA46FBF2FEB8B4C9EB16" italics="true" pageId="21" pageNumber="444">O. peruvianus</emphasis>
|
||
(
|
||
<bibRefCitation id="3244FCBCFF89FA46F9A2FEA6B5DDEB17" author="de Muizon C & Domning DP & Ketten DR" box="[251,511,350,373]" pageId="21" pageNumber="444" refId="ref23097" refString="de Muizon C, Domning DP, Ketten DR. 2002. Odobenocetops peruvianus, the walrus-convergent delphinoid (Cetacea, Mammalia) from the lower Pliocene of Peru. Smithsonian Contribution to Paleobiology 93: in press." type="book" year="2002">
|
||
de Muizon
|
||
<emphasis id="64A15D5FFF89FA46F825FEA7B58CEB11" box="[380,430,350,372]" italics="true" pageId="21" pageNumber="444">et al</emphasis>
|
||
., 2002
|
||
</bibRefCitation>
|
||
)
|
||
</taxonomicName>
|
||
.
|
||
</paragraph>
|
||
<paragraph id="566A814DFF89FA46F9E1FE85B5B4E8A4" blockId="21.[159,776,197,710]" pageId="21" pageNumber="444">
|
||
The occipital condyles are more convex and salient than in any recent delphinoid and confirm the great mobility of the neck which was noted with regard to the
|
||
<typeStatus id="896E3FEFFF89FA46F988FE21B517EB8D" box="[209,309,473,495]" pageId="21" pageNumber="444" type="holotype">holotype</typeStatus>
|
||
. In fact, the occipital condyles form a quarter of a sphere (
|
||
<figureCitation id="CEEE9DC8FF89FA46F8FFFE00B60CE86F" box="[422,558,504,526]" captionStart="Figure 13" captionStartId="17.[159,238,1371,1392]" captionTargetBox="[349,1251,194,1339]" captionTargetId="figure-258@17.[344,1305,172,1349]" captionTargetPageId="17" captionText="Figure 13. Odobenocetops peruvianus, referred specimen (SMNK PAL 2491). Skull of a probable female in dorsal (A), ventral (B), occipital (D), and anteroventral (E) views; posteroventral view of the anterior region of the palate showing the two small tusks (C)." figureDoi="http://doi.org/10.5281/zenodo.4687211" httpUri="https://zenodo.org/record/4687211/files/figure.png" pageId="21" pageNumber="444">Figs 13B,D</figureCitation>
|
||
and
|
||
<figureCitation id="CEEE9DC8FF89FA46FB2FFE00B6B3E86C" box="[630,657,504,526]" captionStart="Figure 14" captionStartId="18.[145,224,1854,1875]" captionTargetBox="[157,1410,1469,1821]" captionTargetId="figure-669@18.[139,1420,1459,1855]" captionTargetPageId="18" captionText="Figure 14. Odobenocetops peruvianus, referred specimen (SMNK PAL 2491). Skull of a probable female in lateral right (A) and lateral left (B) views." figureDoi="http://doi.org/10.5281/zenodo.4687213" httpUri="https://zenodo.org/record/4687213/files/figure.png" pageId="21" pageNumber="444">14</figureCitation>
|
||
) and are proportionally larger and more convex than in any other cetacean (Recent or fossil) or in the walrus. The morphology of the condyles of SMNK PAL 2491 therefore indicates an exceptional mobility of the neck in
|
||
<taxonomicName id="91D5FACEFF89FA46F9E4FD69B546E8C4" authorityName="PERUVIANUS MUIZON" authorityYear="1993" box="[189,356,657,678]" class="Mammalia" family="Odobenocetopsidae" genus="Odobenocetops" higherTaxonomySource="GBIF" kingdom="Animalia" order="Cetacea" pageId="21" pageNumber="444" phylum="Chordata" rank="genus">
|
||
<emphasis id="64A15D5FFF89FA46F9E4FD69B546E8C4" box="[189,356,657,678]" italics="true" pageId="21" pageNumber="444">Odobenocetops</emphasis>
|
||
</taxonomicName>
|
||
; certainly much greater than that of any other odontocete.
|
||
</paragraph>
|
||
</subSubSection>
|
||
</treatment>
|
||
</document> |