697 lines
115 KiB
XML
697 lines
115 KiB
XML
<document id="64514187BAEDFEC9248AAAEF6CB274EE" ID-DOI="10.1016/j.cretres.2015.12.016" ID-GBIF-Dataset="01816227-cd8c-4f5f-904f-e78a7c90c64c" ID-Zenodo-Dep="3890523" IM.treatments_approvedBy="admin" approvalRequired="2" approvalRequired_for_document="1" approvalRequired_for_taxonomicNames="1" checkinTime="1591188450091" checkinUser="jeremy" docAuthor="Joshua D. Schmerge & Bruce M. Rothschild" docDate="2016" docId="03DC7E37F05AFFA3FF49FE18FBD9FA1D" docLanguage="en" docName="SchmergeRothschild2016.pdf.imf" docOrigin="Cretaceous Research 61" docStyle="DocumentStyle{}" docTitle="Nanotyrannus lancensis" docType="treatment" docVersion="10" lastPageNumber="31" masterDocId="FFE5064FF05BFFA6FFD8FFD2FFFDFFF8" masterDocTitle="Distribution of the dentary groove of theropod dinosaurs: Implications for theropod phylogeny and the validity of the genus Nanotyrannus Bakker et al., 1988" masterLastPageNumber="33" masterPageNumber="26" pageNumber="27" updateTime="1697418797726" updateUser="admin">
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<mods:titleInfo id="02570600D84BBE5B3AA67577FB4E3C2C">
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<mods:title id="8A5D67538B208419B8DDA1DCA61E92F1">Distribution of the dentary groove of theropod dinosaurs: Implications for theropod phylogeny and the validity of the genus Nanotyrannus Bakker et al., 1988</mods:title>
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<mods:name id="79A6EE634FA06E695F09104F79BA2ABB" type="personal">
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<mods:roleTerm id="6507A6DC1E69298A0E9D7D2CA0C20556">Author</mods:roleTerm>
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<mods:namePart id="72743593791B7362C38698572FFBFEB1">Joshua D. Schmerge</mods:namePart>
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<mods:affiliation id="5159F08024B6F76FE32C0BC5D51A83C1">Biodiversity Institute, University of Kansas, 1345 Jayhawk Blvd., Lawrence, KS, 66045, USA</mods:affiliation>
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<mods:nameIdentifier id="C046C02AFB1B75DECC5AA414F8B28954" type="email">schmerge@ku.edu</mods:nameIdentifier>
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<mods:name id="F8D6FD3D1F4D216C9C94851C2CFCD792" type="personal">
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<mods:namePart id="0620BB98BD13C42F8C648D52F8AB487F">Bruce M. Rothschild</mods:namePart>
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<mods:affiliation id="B1835859F1B7F165DED6DE61DB42E00E">Department of Vertebrate Paleontology, Carnegie Museum, 4400 Forbes Ave., Pittsburgh, PA, 44272, USA</mods:affiliation>
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<mods:typeOfResource id="BBC3D4DC6DE8156098D8E140546E9969">text</mods:typeOfResource>
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<mods:title id="40640FD3BACF1FA16D9A317637EE5E9D">Cretaceous Research</mods:title>
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<mods:part id="0BE22361F4A1BEA393E9F2013AF012BE">
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<mods:date id="6BC7FF58E5FBD79534027859548803C2">2016</mods:date>
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<mods:number id="DBAADA3F4F86FC6530E57AD63D639825">2015-12-27</mods:number>
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<mods:detail id="6C6ECC40A76C4009CC21EB0975E0EEEA" type="volume">
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<mods:number id="C8493F3C8CD2769C370E03889DB1E8FE">61</mods:number>
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<mods:classification id="BB4E97104625A658FF237227C2BD6121">journal article</mods:classification>
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<mods:identifier id="9E3E30A95DD404E3553AA9D37D75A8B6" type="DOI">10.1016/j.cretres.2015.12.016</mods:identifier>
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<treatment id="03DC7E37F05AFFA3FF49FE18FBD9FA1D" ID-DOI="http://doi.org/10.5281/zenodo.4715039" ID-GBIF-Taxon="168816243" ID-Zenodo-Dep="4715039" LSID="urn:lsid:plazi:treatment:03DC7E37F05AFFA3FF49FE18FBD9FA1D" httpUri="http://treatment.plazi.org/id/03DC7E37F05AFFA3FF49FE18FBD9FA1D" lastPageId="5" lastPageNumber="31" pageId="1" pageNumber="27">
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<subSubSection id="C36F9CAAF05AFFA7FF49FE18FF47FD20" pageId="1" pageNumber="27" type="description">
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<paragraph id="8BCACF21F05AFFA7FF49FE18FF47FD20" blockId="1.[113,784,179,1091]" pageId="1" pageNumber="27">
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The phylogenetic distribution of the lateral dentary groove was investigated to determine the polarity of the character, to interpret the implication of its losses, and to assess its potential as a diagnostic feature for re-classifying the position of
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<materialsCitation id="3B1DC57CF05AFFA7FD53FDCCFF26FDB5" ID-GBIF-Occurrence="2960701305" collectionCode="BMR" pageId="1" pageNumber="27" specimenCode="BMR P2002.4.1">“Jane” (BMR P2002.4.1)</materialsCitation>
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and other specimens labeled
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<taxonomicName id="4C75B4A2F05AFFA7FDECFDEBFD40FDB5" baseAuthorityName="Gilmore" baseAuthorityYear="1946" box="[564,701,569,589]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="species" species="lancensis">
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<emphasis id="B9011333F05AFFA7FDECFDEBFD40FDB5" box="[564,701,569,589]" italics="true" pageId="1" pageNumber="27">Nanotyrannus</emphasis>
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</taxonomicName>
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within Tyrannosauroidea. “Jane” is clearly a tyrannosaurid (
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<bibRefCitation id="EFE4B2D0F05AFFA7FD58FD84FF5CFD7D" author="Brusatte, S. L. & Norell, M. A. & Carr, T. D. & Erickson, G. M. & Hutchinson, J. R. & Balanoff, A. M. & Bever, G. S. & Choiniere, J. N. & Makovicky, P. J. & Xu, X." journalOrPublisher="Science" pageId="1" pageNumber="27" pagination="1481 - 1485" part="329" refId="ref5776" refString="Brusatte, S. L., Norell, M. A., Carr, T. D., Erickson, G. M., Hutchinson, J. R., Balanoff, A. M., Bever, G. S., Choiniere, J. N., Makovicky, P. J., Xu, X., 2010. Tyrannosaur paleobiology: new research on ancient exemplar organisms. Science 329, 1481 - 1485." title="Tyrannosaur paleobiology: new research on ancient exemplar organisms" type="journal article" year="2010">Brusatte et al., 2010</bibRefCitation>
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), but its taxonomic affiliation has been highly disputed (
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<bibRefCitation id="EFE4B2D0F05AFFA7FFA1FD5FFEA8FD58" author="Erickson, G. M. & Currie, P. J. & Inouye, B. D. & Winn, A. A." box="[121,341,653,673]" journalOrPublisher="Science" pageId="1" pageNumber="27" pagination="213 - 217" part="313" refId="ref6411" refString="Erickson, G. M., Currie, P. J., Inouye, B. D., Winn, A. A., 2006. Tyrannosaur life tables: an example of nonavian dinosaur population biology. Science 313, 213 - 217." title="Tyrannosaur life tables: an example of nonavian dinosaur population biology" type="journal article" year="2006">Erickson et al., 2006</bibRefCitation>
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;
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<bibRefCitation id="EFE4B2D0F05AFFA7FEBCFD5FFD89FD59" author="Snively, E. & Russell, A. P." box="[356,628,653,673]" journalOrPublisher="Anatomical Record" pageId="1" pageNumber="27" pagination="934 - 957" part="290" refId="ref7816" refString="Snively, E., Russell, A. P., 2007. Functional variation of neck muscles and their relation to feeding style in Tyrannosauridae and other large theropod dinosaurs. Anatomical Record 290, 934 - 957." title="Functional variation of neck muscles and their relation to feeding style in Tyrannosauridae and other large theropod dinosaurs" type="journal article" year="2007">Snively and Russell, 2007</bibRefCitation>
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;
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<bibRefCitation id="EFE4B2D0F05AFFA7FD5AFD5CFCF6FD59" author="Larson, P." box="[642,779,654,673]" editor="Larson, P. & Carpenter, K." journalOrPublisher="Indiana University Press, Bloomington, Indiana" pageId="1" pageNumber="27" pagination="102 - 128" refId="ref6886" refString="Larson, P., 2008. Variation and sexual dimorphism in Tyrannosaurus rex. In: Larson, P., Carpenter, K. (Eds.), Tyrannosaurus Rex: The Tyrant King. Indiana University Press, Bloomington, Indiana, pp. 102 - 128." title="Variation and sexual dimorphism in Tyrannosaurus rex" type="book chapter" volumeTitle="Tyrannosaurus Rex: The Tyrant King" year="2008">Larson, 2008</bibRefCitation>
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;
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<bibRefCitation id="EFE4B2D0F05AFFA7FFA9FD7BFE3DFD45" author="Henderson, M. D. & Harrison, W. H." box="[113,448,681,701]" editor="Larson, P. & Carpenter, K." journalOrPublisher="Indiana University Press, Bloomington, Indiana" pageId="1" pageNumber="27" pagination="82 - 90" refId="ref6665" refString="Henderson, M. D., Harrison, W. H., 2008. Taphonomy and environment of deposition of a juvenile tyrannosaurid skeleton from the Hell Creek Formation (Latest Maastrichtian) of southeastern Montana. In: Larson, P., Carpenter, K. (Eds.), Tyrannosaurus Rex: The Tyrant King. Indiana University Press, Bloomington, Indiana, pp. 82 - 90." title="Taphonomy and environment of deposition of a juvenile tyrannosaurid skeleton from the Hell Creek Formation (Latest Maastrichtian) of southeastern Montana" type="book chapter" volumeTitle="Tyrannosaurus Rex: The Tyrant King" year="2008">Henderson and Harrison, 2008</bibRefCitation>
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;
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<bibRefCitation id="EFE4B2D0F05AFFA7FE09FD78FD4BFD45" author="Peterson, J. E. & Henderson, M. D. & Scherer, R. P. & Vittore, C. P." box="[465,694,681,701]" journalOrPublisher="PALAIOS" pageId="1" pageNumber="27" pagination="780 - 784" part="24" refId="ref7534" refString="Peterson, J. E., Henderson, M. D., Scherer, R. P., Vittore, C. P., 2009. Face biting on a juvenile tyrannosaurid and behavioral implications. PALAIOS 24, 780 - 784." title="Face biting on a juvenile tyrannosaurid and behavioral implications" type="journal article" year="2009">Peterson et al., 2009</bibRefCitation>
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;
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<bibRefCitation id="EFE4B2D0F05AFFA7FD1FFD78FF50FD20" author="Larson, P." editor="Parrish, J. M. & Molnar, R. E. & Currie, P. J. & Koppelhus, E. B." journalOrPublisher="Indiana University Press, Bloomington, Indiana" pageId="1" pageNumber="27" pagination="14 - 53" refId="ref6938" refString="Larson, P., 2013 a. The case for Nanotyrannus. In: Parrish, J. M., Molnar, R. E., Currie, P. J., Koppelhus, E. B. (Eds.), Tyrannosaurid Paleobiology. Indiana University Press, Bloomington, Indiana, pp. 14 - 53." title="The case for Nanotyrannus" type="book chapter" volumeTitle="Tyrannosaurid Paleobiology" year="2013">Larson, 2013a</bibRefCitation>
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).
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</paragraph>
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</subSubSection>
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<subSubSection id="C36F9CAAF05AFFA7FF19FD17FEBEFCE8" pageId="1" pageNumber="27" type="nomenclature">
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<paragraph id="8BCACF21F05AFFA7FF19FD17FEBEFCE8" blockId="1.[113,784,179,1091]" pageId="1" pageNumber="27">
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The debate over “Jane” is a smaller part of a larger debate about the validity of
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<taxonomicName id="4C75B4A2F05AFFA7FE97FD32FDC7FD0C" baseAuthorityName="Gilmore" baseAuthorityYear="1946" box="[335,570,736,756]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="species" species="lancensis">
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<emphasis id="B9011333F05AFFA7FE97FD32FDC7FD0C" box="[335,570,736,756]" italics="true" pageId="1" pageNumber="27">Nanotyrannus lancensis</emphasis>
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</taxonomicName>
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as a separate genus (
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<bibRefCitation id="EFE4B2D0F05AFFA7FFA1FD2FFECBFCE8" author="Bakker, R. T. & William, M. & Currie, P." box="[121,310,765,785]" journalOrPublisher="Hunteria" pageId="1" pageNumber="27" pagination="1 - 28" part="1" refId="ref5494" refString="Bakker, R. T., William, M., Currie, P., 1988. Nanotyrannus, a new genus of pygmy tyrannosaur, from the Latest Cretaceous of Montana. Hunteria 1, 1 - 28." title="Nanotyrannus, a new genus of pygmy tyrannosaur, from the Latest Cretaceous of Montana" type="journal article" year="1988">Bakker et al., 1988</bibRefCitation>
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).
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</paragraph>
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</subSubSection>
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<subSubSection id="C36F9CAAF05AFFA7FE93FD2FFE34FBBB" pageId="1" pageNumber="27" type="description">
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<paragraph id="8BCACF21F05AFFA7FE93FD2FFE34FBBB" blockId="1.[113,784,179,1091]" pageId="1" pageNumber="27">
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Three specimens have taken center stage in this debate: “
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<materialsCitation id="3B1DC57CF05AFFA7FF23FCCBFEDBFCD4" ID-GBIF-Occurrence="2960701312" box="[251,294,793,812]" collectionCode="BMR" pageId="1" pageNumber="27" specimenCode="BMR P2002.4.1">Jane</materialsCitation>
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”, the holotype specimen of
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<taxonomicName id="4C75B4A2F05AFFA7FD91FCCAFD40FCD4" baseAuthorityName="Gilmore" baseAuthorityYear="1946" box="[585,701,792,812]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="species" species="lancensis">
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<emphasis id="B9011333F05AFFA7FD91FCCAFD40FCD4" box="[585,701,792,812]" italics="true" pageId="1" pageNumber="27">N. lancensis</emphasis>
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</taxonomicName>
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(
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<materialsCitation id="3B1DC57CF05AFFA7FD13FCCBFF58FCB0" ID-GBIF-Occurrence="2960701307" collectionCode="CMNH" pageId="1" pageNumber="27" specimenCode="CMNH 7531">CMNH 7531</materialsCitation>
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), and the theropod described as one of the “Dueling Dinosaurs” (
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<materialsCitation id="3B1DC57CF05AFFA7FF0EFC83FEC4FC9C" ID-GBIF-Occurrence="2960701310" box="[214,313,849,868]" collectionCode="BHI" pageId="1" pageNumber="27" specimenCode="BHI 6437">BHI 6437</materialsCitation>
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;
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<bibRefCitation id="EFE4B2D0F05AFFA7FE9CFC83FE32FC9C" author="Larson, P." box="[324,463,849,868]" journalOrPublisher="Journal of Vertebrate Paleontology" pageId="1" pageNumber="27" pagination="159 A" part="33" refId="ref7002" refString="Larson, P., 2013 b. The validity of Nanotyrannus lancensis (Theropoda, Lancian - Upper Maastrichtian of North America. Journal of Vertebrate Paleontology 33, 159 A." title="The validity of Nanotyrannus lancensis (Theropoda, Lancian - Upper Maastrichtian of North America" type="journal article" year="2013">Larson, 2013b</bibRefCitation>
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). The debate presently rests on three competing hypotheses, either that 1)
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<taxonomicName id="4C75B4A2F05AFFA7FDFCFCB9FD50FC87" authority="Bakker et al., 1988" authorityName="Bakker et al." authorityYear="1988" box="[548,685,875,895]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
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<emphasis id="B9011333F05AFFA7FDFCFCB9FD50FC87" box="[548,685,875,895]" italics="true" pageId="1" pageNumber="27">Nanotyrannus</emphasis>
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</taxonomicName>
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stands as a valid taxon (
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<bibRefCitation id="EFE4B2D0F05AFFA7FEDFFC5BFE68FC64" author="Currie, P. J." box="[263,405,905,924]" journalOrPublisher="Acta Palaeontologica Polonica" pageId="1" pageNumber="27" pagination="191 - 226" part="48" refId="ref6096" refString="Currie, P. J., 2003 a. Cranial anatomy of tyrannosaurid dinosaus from the Late Cretaceous of Alberta, Canada. Acta Palaeontologica Polonica 48, 191 - 226." title="Cranial anatomy of tyrannosaurid dinosaus from the Late Cretaceous of Alberta, Canada" type="journal article" year="2003">Currie, 2003a</bibRefCitation>
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;
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<bibRefCitation id="EFE4B2D0F05AFFA7FE79FC5BFDD1FC64" author="Larson, P." box="[417,556,905,924]" editor="Parrish, J. M. & Molnar, R. E. & Currie, P. J. & Koppelhus, E. B." journalOrPublisher="Indiana University Press, Bloomington, Indiana" pageId="1" pageNumber="27" pagination="14 - 53" refId="ref6938" refString="Larson, P., 2013 a. The case for Nanotyrannus. In: Parrish, J. M., Molnar, R. E., Currie, P. J., Koppelhus, E. B. (Eds.), Tyrannosaurid Paleobiology. Indiana University Press, Bloomington, Indiana, pp. 14 - 53." title="The case for Nanotyrannus" type="book chapter" volumeTitle="Tyrannosaurid Paleobiology" year="2013">Larson, 2013a</bibRefCitation>
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); 2) these individuals represent the taxon
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<taxonomicName id="4C75B4A2F05AFFA7FEE2FC71FDDAFC4F" authorityName="Currie et al." authorityYear="2005" baseAuthorityName="Gilmore" baseAuthorityYear="1946" box="[314,551,931,951]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="species" species="lancensis">
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<emphasis id="B9011333F05AFFA7FEE2FC71FDDAFC4F" box="[314,551,931,951]" italics="true" pageId="1" pageNumber="27">Tyrannosaurus lancensis</emphasis>
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</taxonomicName>
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(
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<bibRefCitation id="EFE4B2D0F05AFFA7FDECFC77FD19FC4F" author="Currie, P. J. & Henderson, M. & Horner, J. R. & Williams, S. A." box="[564,740,932,952]" journalOrPublisher="Abstracts" pageId="1" pageNumber="27" pagination="19" refId="ref6209" refString="Currie, P. J., Henderson, M., Horner, J. R., Williams, S. A., 2005. On tyrannosaur teeth, tooth positions and the taxonomic status of Nanotyrannus lancensis. In: The Origin, Systematics, and Paleobiology of Tyrannosauridae Symposium. Abstracts: 19." title="On tyrannosaur teeth, tooth positions and the taxonomic status of Nanotyrannus lancensis" type="proceedings" volumeTitle="The Origin, Systematics, and Paleobiology of Tyrannosauridae Symposium" year="2005">Currie et al., 2005</bibRefCitation>
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); or 3) these individuals are juvenile
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<taxonomicName id="4C75B4A2F05AFFA7FE0BFC6DFD76FC2B" authorityName="Osborn" authorityYear="1905" box="[467,651,959,979]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="33" phylum="Chordata" rank="species" species="rex">
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<emphasis id="B9011333F05AFFA7FE0BFC6DFD76FC2B" box="[467,651,959,979]" italics="true" pageId="1" pageNumber="27">Tyrannosaurus rex</emphasis>
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</taxonomicName>
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(
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<bibRefCitation id="EFE4B2D0F05AFFA7FD46FC12FCF6FC2B" author="Carr, T. D." box="[670,779,960,979]" journalOrPublisher="Journal of Vertebrate Paleontology" pageId="1" pageNumber="27" pagination="497 - 520" part="19" refId="ref5906" refString="Carr, T. D., 1999. Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria). Journal of Vertebrate Paleontology 19, 497 - 520." title="Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria)" type="journal article" year="1999">Carr, 1999</bibRefCitation>
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;
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<bibRefCitation id="EFE4B2D0F05AFFA7FFA9FC0EFF01FC17" author="Brochu, C. A." box="[113,252,988,1007]" journalOrPublisher="Journal of Vertebrate Paleontology Memoir" pageId="1" pageNumber="27" pagination="1 - 138" part="7" refId="ref5630" refString="Brochu, C. A., 2003. Osteology of Tyrannosaurus rex: insights from a nearly complete skeleton and high-resolution computed tomographic analysis of the skull. Journal of Vertebrate Paleontology Memoir 7, 1 - 138." title="Osteology of Tyrannosaurus rex: insights from a nearly complete skeleton and high-resolution computed tomographic analysis of the skull" type="journal article" year="2003">Brochu, 2003</bibRefCitation>
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;
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<bibRefCitation id="EFE4B2D0F05AFFA7FEDFFC0EFDE0FC17" author="Carr, T. D. & Williamson, T. E." box="[263,541,988,1007]" journalOrPublisher="Zoological Journal of the Linnean Society" pageId="1" pageNumber="27" pagination="479 - 523" part="142" refId="ref5935" refString="Carr, T. D., Williamson, T. E., 2004. Diversity of late Maastrichtian Tyrannosauridae (Dinosauria: Theropoda) from western North America. Zoological Journal of the Linnean Society 142, 479 - 523." title="Diversity of late Maastrichtian Tyrannosauridae (Dinosauria: Theropoda) from western North America" type="journal article" year="2004">Carr and Williamson, 2004</bibRefCitation>
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;
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<bibRefCitation id="EFE4B2D0F05AFFA7FDF1FC0EFD62FC17" author="Holtz, T. R." box="[553,671,988,1007]" editor="Weishampel, D. B. & Dodson, P. & Osmolska, H." journalOrPublisher="University of California Press, Los Angeles, California" pageId="1" pageNumber="27" pagination="111 - 136" refId="ref6741" refString="Holtz, T. R., 2004. Tyrannosauroidea. In: Weishampel, D. B., Dodson, P., Osmolska, H. (Eds.), The Dinosauria. University of California Press, Los Angeles, California, pp. 111 - 136." title="Tyrannosauroidea" type="book chapter" volumeTitle="The Dinosauria" year="2004">Holtz, 2004</bibRefCitation>
|
|
). A goal of this study is to attempt to clarify the relationship of
|
|
<taxonomicName id="4C75B4A2F05AFFA7FD42FC25FCF2FBF3" baseAuthorityName="Gilmore" baseAuthorityYear="1946" box="[666,783,1015,1035]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="species" species="lancensis">
|
|
<emphasis id="B9011333F05AFFA7FD42FC25FCF2FBF3" box="[666,783,1015,1035]" italics="true" pageId="1" pageNumber="27">N. lancensis</emphasis>
|
|
</taxonomicName>
|
|
with other tyrannosaurids using the dentary groove and other cranial characters (
|
|
<bibRefCitation id="EFE4B2D0F05AFFA7FEEAFBE2FE46FBBB" author="Larson, P." box="[306,443,1072,1091]" editor="Parrish, J. M. & Molnar, R. E. & Currie, P. J. & Koppelhus, E. B." journalOrPublisher="Indiana University Press, Bloomington, Indiana" pageId="1" pageNumber="27" pagination="14 - 53" refId="ref6938" refString="Larson, P., 2013 a. The case for Nanotyrannus. In: Parrish, J. M., Molnar, R. E., Currie, P. J., Koppelhus, E. B. (Eds.), Tyrannosaurid Paleobiology. Indiana University Press, Bloomington, Indiana, pp. 14 - 53." title="The case for Nanotyrannus" type="book chapter" volumeTitle="Tyrannosaurid Paleobiology" year="2013">Larson, 2013a</bibRefCitation>
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).
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</paragraph>
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|
</subSubSection>
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|
<subSubSection id="C36F9CAAF05AFFA7FFA9FBBAFC77F93D" pageId="1" pageNumber="27" type="description">
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|
<paragraph id="8BCACF21F05AFFA7FFA9FBBAFE7AFB83" blockId="1.[113,391,1128,1147]" box="[113,391,1128,1147]" pageId="1" pageNumber="27">
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|
<heading id="D082784DF05AFFA7FFA9FBBAFE7AFB83" bold="true" box="[113,391,1128,1147]" fontSize="8" level="2" pageId="1" pageNumber="27" reason="0">
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|
<emphasis id="B9011333F05AFFA7FFA9FBBAFE7AFB83" bold="true" box="[113,391,1128,1147]" pageId="1" pageNumber="27">2. Materials and methods</emphasis>
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</heading>
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</paragraph>
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<paragraph id="8BCACF21F05AFFA7FF49FB72FCEDF9C1" blockId="1.[113,784,1183,1984]" pageId="1" pageNumber="27">
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|
We investigated 92 theropod taxa for presence or absence of a groove on the lateral surface of the dentary (
|
|
<figureCitation id="134ED3A4F05AFFA7FDBEFB69FD5DFB37" box="[614,672,1211,1231]" captionStart="Fig" captionStartId="2.[88,113,1773,1787]" captionTargetBox="[101,1462,304,1744]" captionTargetId="figure@2.[101,1462,304,1744]" captionTargetPageId="2" captionText="Fig. 1. Lateral views of theropod skulls demonstrating presence or absence of the dentary groove. The dentary groove is present in the primitive theropod (A) Coelophysis bauri (NMMNH P-42200), as well as in the derived theropod (B) Compsognathus longipes (BSP AS I 563). The dentary groove is present in the tyrannosaurids (C) Gorgosaurus libratus (TCM 2001.89.1) and (D) Nanotyrannus lancensis (“Jane”; BMR P2002.4.1). The dentary groove is absent in both (E1) young (LACM 28471) and (E2) adult (“Sue”; FMNH PR2081) Tyrannosaurus rex. Arrows indicate the position of the groove, when present. Scale bars equal 5 cm." figureDoi="http://doi.org/10.5281/zenodo.3890525" httpUri="https://zenodo.org/record/3890525/files/figure.png" pageId="1" pageNumber="27">Fig. 1</figureCitation>
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|
). We also examined photographs of the crocodylomorph
|
|
<taxonomicName id="4C75B4A2F05AFFA7FDBCFB04FD23FB12" authorityName="Chatterjee" authorityYear="1993" box="[612,734,1238,1258]" class="Reptilia" family="Shuvosauridae" genus="Shuvosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Saurischia" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
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|
<emphasis id="B9011333F05AFFA7FDBCFB04FD23FB12" box="[612,734,1238,1258]" italics="true" pageId="1" pageNumber="27">Shuvosaurus</emphasis>
|
|
</taxonomicName>
|
|
, the early dinosaurs
|
|
<taxonomicName id="4C75B4A2F05AFFA7FEC5FB20FE5AFAFE" authorityName="Reig" authorityYear="1963" box="[285,423,1266,1286]" class="Reptilia" family="Herrerasauridae" genus="Herrerasaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05AFFA7FEC5FB20FE5AFAFE" box="[285,423,1266,1286]" italics="true" pageId="1" pageNumber="27">Herrerasaurus</emphasis>
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|
</taxonomicName>
|
|
and
|
|
<taxonomicName id="4C75B4A2F05AFFA7FE3CFB20FD89FAFE" authorityName="Colbert" authorityYear="1970" box="[484,628,1266,1286]" class="Reptilia" family="Herrerasauridae" genus="Staurikosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05AFFA7FE3CFB20FD89FAFE" box="[484,628,1266,1286]" italics="true" pageId="1" pageNumber="27">Staurikosaurus</emphasis>
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|
</taxonomicName>
|
|
, and the sauropodomorphs
|
|
<emphasis id="B9011333F05AFFA7FECEFADCFE95FADA" box="[278,360,1294,1314]" italics="true" pageId="1" pageNumber="27">Eoraptor</emphasis>
|
|
,
|
|
<emphasis id="B9011333F05AFFA7FEA4FADCFE1BFADA" box="[380,486,1294,1314]" italics="true" pageId="1" pageNumber="27">Leyesaurus</emphasis>
|
|
,
|
|
<emphasis id="B9011333F05AFFA7FE21FADCFD67FADA" box="[505,666,1294,1314]" italics="true" pageId="1" pageNumber="27">Pampadromaeus</emphasis>
|
|
, and
|
|
<taxonomicName id="4C75B4A2F05AFFA7FD3AFADCFF4EFAC6" authorityName="Martinez & Alcober" authorityYear="2009" class="Reptilia" family="Guaibasauridae" genus="Panphagia" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05AFFA7FD3AFADCFF4EFAC6" italics="true" pageId="1" pageNumber="27">Panphagia</emphasis>
|
|
</taxonomicName>
|
|
for comparison. Sampled taxa and reviewed published records are delineated in the
|
|
<httpUri id="B5F4118BF05AFFA7FE44FA95FDA5FAA2" box="[412,600,1351,1370]" httpUri="https://ars-els-cdn-com.naturalis.idm.oclc.org/content/image/1-s2.0-S0195667115301415-mmc1.docx" pageId="1" pageNumber="27">supplemental data</httpUri>
|
|
. We relied on descriptions of holotypes whenever possible, to avoid controversy as to taxonomic assignment. Some sampled specimens are the subject of debate (e.g. “Jane”) and the attribution of some unpublished specimens is controversial (e.g., assignment of specimens to
|
|
<emphasis id="B9011333F05AFFA7FD31FA67FEC7FA1D" italics="true" pageId="1" pageNumber="27">
|
|
<taxonomicName id="4C75B4A2F05AFFA7FD31FA67FF34FA1D" authorityName="Stromer" authorityYear="1915" class="Reptilia" family="Spinosauridae" genus="Spinosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">Spinosaurus</taxonomicName>
|
|
aegypticus
|
|
</emphasis>
|
|
). When such published descriptions did not include photographs of the specimen(s) or presence or absence of the groove was not unambiguously depicted in an illustration, we examined images of additional congeneric specimens, as available.
|
|
</paragraph>
|
|
<paragraph id="8BCACF21F05AFFA7FF49F990FD24F838" blockId="1.[113,784,1183,1984]" pageId="1" pageNumber="27">
|
|
Phylogenetic analyses were conducted using TNT v1.1 (
|
|
<bibRefCitation id="EFE4B2D0F05AFFA7FD61F990FF1CF989" author="Goloboff, P. A. & Farris, J. S. & Nixon, K. C." journalOrPublisher="Cladistics" pageId="1" pageNumber="27" pagination="774 - 786" part="24" refId="ref6626" refString="Goloboff, P. A., Farris, J. S., Nixon, K. C., 2008. TNT, a free program for phylogenetic analysis. Cladistics 24, 774 - 786." title="TNT, a free program for phylogenetic analysis" type="journal article" year="2008">Goloboff et al., 2008</bibRefCitation>
|
|
). We utilized the methodology and character matrix of
|
|
<bibRefCitation id="EFE4B2D0F05AFFA7FFA9F9A8FEBCF975" author="Brusatte, S. L. & Norell, M. A. & Carr, T. D. & Erickson, G. M. & Hutchinson, J. R. & Balanoff, A. M. & Bever, G. S. & Choiniere, J. N. & Makovicky, P. J. & Xu, X." box="[113,321,1658,1677]" journalOrPublisher="Science" pageId="1" pageNumber="27" pagination="1481 - 1485" part="329" refId="ref5776" refString="Brusatte, S. L., Norell, M. A., Carr, T. D., Erickson, G. M., Hutchinson, J. R., Balanoff, A. M., Bever, G. S., Choiniere, J. N., Makovicky, P. J., Xu, X., 2010. Tyrannosaur paleobiology: new research on ancient exemplar organisms. Science 329, 1481 - 1485." title="Tyrannosaur paleobiology: new research on ancient exemplar organisms" type="journal article" year="2010">Brusatte et al. (2010)</bibRefCitation>
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|
, and modified it only by adding
|
|
<taxonomicName id="4C75B4A2F05AFFA7FD5EF9AAFCF2F974" authorityName="Bakker et al." authorityYear="1988" box="[646,783,1656,1676]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05AFFA7FD5EF9AAFCF2F974" box="[646,783,1656,1676]" italics="true" pageId="1" pageNumber="27">Nanotyrannus</emphasis>
|
|
</taxonomicName>
|
|
to the character matrix and coding the dentary groove as present in
|
|
<emphasis id="B9011333F05AFFA7FFA9F962FF0EF93C" box="[113,243,1712,1732]" italics="true" pageId="1" pageNumber="27">Dryptosaurus</emphasis>
|
|
, without modification of any other characters. The character matrix is included in the
|
|
<httpUri id="B5F4118BF05AFFA7FE15F91FFD81F918" box="[461,636,1741,1760]" httpUri="https://ars-els-cdn-com.naturalis.idm.oclc.org/content/image/1-s2.0-S0195667115301415-mmc1.docx" pageId="1" pageNumber="27">supplemental file</httpUri>
|
|
. We coded the character matrix for
|
|
<taxonomicName id="4C75B4A2F05AFFA7FE9AF93AFE36F904" authorityName="Bakker et al." authorityYear="1988" box="[322,459,1768,1788]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05AFFA7FE9AF93AFE36F904" box="[322,459,1768,1788]" italics="true" pageId="1" pageNumber="27">Nanotyrannus</emphasis>
|
|
</taxonomicName>
|
|
based on personal observations of skull of “Jane” at the Burpee Museum. Presence of the groove is character 176 of
|
|
<bibRefCitation id="EFE4B2D0F05AFFA7FECFF8F0FE1AF8CC" author="Brusatte, S. L. & Norell, M. A. & Carr, T. D. & Erickson, G. M. & Hutchinson, J. R. & Balanoff, A. M. & Bever, G. S. & Choiniere, J. N. & Makovicky, P. J. & Xu, X." box="[279,487,1825,1845]" journalOrPublisher="Science" pageId="1" pageNumber="27" pagination="1481 - 1485" part="329" refId="ref5776" refString="Brusatte, S. L., Norell, M. A., Carr, T. D., Erickson, G. M., Hutchinson, J. R., Balanoff, A. M., Bever, G. S., Choiniere, J. N., Makovicky, P. J., Xu, X., 2010. Tyrannosaur paleobiology: new research on ancient exemplar organisms. Science 329, 1481 - 1485." title="Tyrannosaur paleobiology: new research on ancient exemplar organisms" type="journal article" year="2010">Brusatte et al. (2010)</bibRefCitation>
|
|
and character 124 of
|
|
<bibRefCitation id="EFE4B2D0F05AFFA7FD18F8F3FF16F8A8" author="Carrano, M. T. & Benson, R. B. J. & Sampson, S. D." journalOrPublisher="Journal of Systematic Palaeontology" pageId="1" pageNumber="27" pagination="211 - 300" part="10" refId="ref5978" refString="Carrano, M. T., Benson, R. B. J., Sampson, S. D., 2012. The phylogeny of Tetanurae (Dinosauria: Theropoda). Journal of Systematic Palaeontology 10, 211 - 300." title="The phylogeny of Tetanurae (Dinosauria: Theropoda)" type="journal article" year="2012">Carrano et al. (2012)</bibRefCitation>
|
|
. We traced the most parsimonious occurrence of this character on the branches of these previously published cladograms to evaluate its use as a diagnostic character in theropods and to evaluate competing phylogenetic hypotheses (
|
|
<figureCitation id="134ED3A4F05AFFA7FDABF843FD4BF85C" box="[627,694,1937,1956]" captionStart="Fig" captionStartId="3.[113,138,1449,1463]" captionTargetBox="[127,1488,180,1419]" captionTargetId="figure@3.[125,1489,178,1420]" captionTargetPageId="3" captionText="Fig. 2. Cladogram of Theropoda modifed from Carrano et al. (2012). Thickened branches indicate lineages possessing the dentary groove, thin branches indicate lineages in which the groove is absent. Grayed-out braches marked with dashed lines indicate taxa without a known dentary. Circled numbers indicate sequence of losses of the dentary groove assuming maximum parsimony." figureDoi="http://doi.org/10.5281/zenodo.3890527" httpUri="https://zenodo.org/record/3890527/files/figure.png" pageId="1" pageNumber="27">Figs. 2</figureCitation>
|
|
-
|
|
<figureCitation id="134ED3A4F05AFFA7FD1EF843FD2EF85C" box="[710,723,1937,1956]" captionStart="Fig" captionStartId="4.[88,113,1624,1638]" captionTargetBox="[222,1339,180,1594]" captionTargetId="figure@4.[221,1340,178,1595]" captionTargetPageId="4" captionText="Fig. 3. Proposed phylogenetic relationships of Nanotyrannus within Tyrannosauroidea with distribution of the theropod dentary groove on trees indicated with thickened bars. (A) Most parsimonious cladogram proposed by this study placing Nanotyrannus as sister to the Albertosaurinae.(B) Relationship sensu Currie (2003a) placing Nanotyrannus as sister to Tyrannosaurus. This tree requires 5 more independent losses of the dentary groove than the tree proposed in this study. (C) Relationship proposed by Brusatte et al. (2010) placing Nanotyrannus as a juvenile Tyrannosaurus. This tree requires 4 more independent losses than the tree proposed in this study and a loss of the dentary groove through ontogeny in Tyrannosaurus." figureDoi="http://doi.org/10.5281/zenodo.3890529" httpUri="https://zenodo.org/record/3890529/files/figure.png" pageId="1" pageNumber="27">3</figureCitation>
|
|
). The most parsimonious result of this study is reported in
|
|
<figureCitation id="134ED3A4F05AFFA7FD56F87FFD28F838" box="[654,725,1965,1984]" captionStart="Fig" captionStartId="4.[88,113,1624,1638]" captionTargetBox="[222,1339,180,1594]" captionTargetId="figure@4.[221,1340,178,1595]" captionTargetPageId="4" captionText="Fig. 3. Proposed phylogenetic relationships of Nanotyrannus within Tyrannosauroidea with distribution of the theropod dentary groove on trees indicated with thickened bars. (A) Most parsimonious cladogram proposed by this study placing Nanotyrannus as sister to the Albertosaurinae.(B) Relationship sensu Currie (2003a) placing Nanotyrannus as sister to Tyrannosaurus. This tree requires 5 more independent losses of the dentary groove than the tree proposed in this study. (C) Relationship proposed by Brusatte et al. (2010) placing Nanotyrannus as a juvenile Tyrannosaurus. This tree requires 4 more independent losses than the tree proposed in this study and a loss of the dentary groove through ontogeny in Tyrannosaurus." figureDoi="http://doi.org/10.5281/zenodo.3890529" httpUri="https://zenodo.org/record/3890529/files/figure.png" pageId="1" pageNumber="27">Fig. 3A</figureCitation>
|
|
.
|
|
</paragraph>
|
|
<paragraph id="8BCACF21F05AFFA7FC87FF61FBBAFE3A" blockId="1.[831,1501,179,450]" pageId="1" pageNumber="27">
|
|
<emphasis id="B9011333F05AFFA7FC87FF61FB23FF3E" bold="true" box="[863,1246,179,198]" pageId="1" pageNumber="27">Institutional Abbreviations―LACM</emphasis>
|
|
, Los Angeles County Museum, Los Angeles, CA;
|
|
<emphasis id="B9011333F05AFFA7FB8DFF1DFB86FF1A" bold="true" box="[1109,1147,207,226]" pageId="1" pageNumber="27">BHI</emphasis>
|
|
, Black Hills Institute of Geological Research, Inc., Hill City, SD;
|
|
<emphasis id="B9011333F05AFFA7FBBEFF39FB6AFF06" bold="true" box="[1126,1175,235,254]" pageId="1" pageNumber="27">BMR</emphasis>
|
|
, Burpee Museum, Rockford, IL;
|
|
<emphasis id="B9011333F05AFFA7FCE7FED5FC99FEE2" bold="true" box="[831,868,263,282]" pageId="1" pageNumber="27">BSP</emphasis>
|
|
, Bayerische Staatsammlung für Paläontologie und historische Geologie, Munich, Germany;
|
|
<emphasis id="B9011333F05AFFA7FBBCFEF1FB5BFECE" bold="true" box="[1124,1190,291,310]" pageId="1" pageNumber="27">CMNH</emphasis>
|
|
, Cleveland Museum of Natural History, Cleveland, OH;
|
|
<emphasis id="B9011333F05AFFA7FBEEFEEDFB8AFEAA" bold="true" box="[1078,1143,319,338]" pageId="1" pageNumber="27">FMNH</emphasis>
|
|
, Field Museum of Natural History, Chicago, IL;
|
|
<emphasis id="B9011333F05AFFA7FC6FFE89FC0CFE96" bold="true" box="[951,1009,347,366]" pageId="1" pageNumber="27">KUVP</emphasis>
|
|
, University of Kansas Museum of Natural History and Biodiversity Institute, Lawrence, KS;
|
|
<emphasis id="B9011333F05AFFA7FB29FEA5FAB6FE72" bold="true" box="[1265,1355,375,394]" pageId="1" pageNumber="27">NMMNH</emphasis>
|
|
, New Mexico Museum of Natural History, Albuquerque, NM;
|
|
<emphasis id="B9011333F05AFFA7FACDFE40FABEFE5D" bold="true" box="[1301,1347,402,421]" pageId="1" pageNumber="27">TCM</emphasis>
|
|
, The Children's Museum, Indianapolis, IN.
|
|
</paragraph>
|
|
<paragraph id="8BCACF21F05AFFA7FCE7FE34FC54FE01" blockId="1.[831,937,486,505]" box="[831,937,486,505]" pageId="1" pageNumber="27">
|
|
<heading id="D082784DF05AFFA7FCE7FE34FC54FE01" bold="true" box="[831,937,486,505]" fontSize="8" level="2" pageId="1" pageNumber="27" reason="0">
|
|
<emphasis id="B9011333F05AFFA7FCE7FE34FC54FE01" bold="true" box="[831,937,486,505]" pageId="1" pageNumber="27">3. Results</emphasis>
|
|
</heading>
|
|
</paragraph>
|
|
<paragraph id="8BCACF21F05AFFA7FC87FDCCFC5AFC9C" blockId="1.[831,1501,542,1733]" pageId="1" pageNumber="27">
|
|
The dentary groove is a unique structure with multiple pores aligned within the depression and sub-equally spaced. The groove originates near the anterior portion of the bone from a position approximately underneath the 2nd to 4th dentary alveolus. It extends caudally along the lateral surface, terminating near the end of the tooth row (
|
|
<figureCitation id="134ED3A4F05AFFA7FBF5FD7BFB99FD45" box="[1069,1124,681,701]" captionStart="Fig" captionStartId="2.[88,113,1773,1787]" captionTargetBox="[101,1462,304,1744]" captionTargetId="figure@2.[101,1462,304,1744]" captionTargetPageId="2" captionText="Fig. 1. Lateral views of theropod skulls demonstrating presence or absence of the dentary groove. The dentary groove is present in the primitive theropod (A) Coelophysis bauri (NMMNH P-42200), as well as in the derived theropod (B) Compsognathus longipes (BSP AS I 563). The dentary groove is present in the tyrannosaurids (C) Gorgosaurus libratus (TCM 2001.89.1) and (D) Nanotyrannus lancensis (“Jane”; BMR P2002.4.1). The dentary groove is absent in both (E1) young (LACM 28471) and (E2) adult (“Sue”; FMNH PR2081) Tyrannosaurus rex. Arrows indicate the position of the groove, when present. Scale bars equal 5 cm." figureDoi="http://doi.org/10.5281/zenodo.3890525" httpUri="https://zenodo.org/record/3890525/files/figure.png" pageId="1" pageNumber="27">Fig. 1</figureCitation>
|
|
; see also figure 1a of
|
|
<bibRefCitation id="EFE4B2D0F05AFFA7FA8AFD78FC31FD20" author="Sampson, S. D. & Witmer, L. M." journalOrPublisher="Journal of Vertebrate Paleontology Memoir" pageId="1" pageNumber="27" pagination="32 - 102" part="8" refId="ref7772" refString="Sampson, S. D., Witmer, L. M., 2007. Craniofacial anatomy of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology Memoir 8, 32 - 102." title="Craniofacial anatomy of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar" type="journal article" year="2007">Sampson and Witmer, 2007</bibRefCitation>
|
|
). This groove does not extend beyond the dentary in examined theropods. This contrasts with the sauropodomorphs
|
|
<emphasis id="B9011333F05AFFA7FCE7FD2EFC6FFCE8" box="[831,914,764,784]" italics="true" pageId="1" pageNumber="27">Eoraptor</emphasis>
|
|
and
|
|
<taxonomicName id="4C75B4A2F05AFFA7FC12FD2EFBD2FCE8" authorityName="Martinez & Alcober" authorityYear="2009" box="[970,1071,764,784]" class="Reptilia" family="Guaibasauridae" genus="Panphagia" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05AFFA7FC12FD2EFBD2FCE8" box="[970,1071,764,784]" italics="true" pageId="1" pageNumber="27">Panphagia</emphasis>
|
|
</taxonomicName>
|
|
, wherein a groove extends onto the surface of the surangular and terminates in a large foramen. Multiple pores were noted along the length of the groove in theropod dinosaurs.
|
|
</paragraph>
|
|
<paragraph id="8BCACF21F05AFFA7FC87FCBFFB0CFBA7" blockId="1.[831,1501,542,1733]" pageId="1" pageNumber="27">
|
|
The dentary groove was present on 48 of 92 sampled theropod taxa (see
|
|
<httpUri id="B5F4118BF05AFFA7FC73FC5BFB90FC64" box="[939,1133,905,924]" httpUri="https://ars-els-cdn-com.naturalis.idm.oclc.org/content/image/1-s2.0-S0195667115301415-mmc1.docx" pageId="1" pageNumber="27">supplemental data</httpUri>
|
|
). No groove was observed in the crocodylomorph
|
|
<taxonomicName id="4C75B4A2F05AFFA7FC34FC71FB9BFC4F" authorityName="Chatterjee" authorityYear="1993" box="[1004,1126,931,951]" class="Reptilia" family="Shuvosauridae" genus="Shuvosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Saurischia" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05AFFA7FC34FC71FB9BFC4F" box="[1004,1126,931,951]" italics="true" pageId="1" pageNumber="27">Shuvosaurus</emphasis>
|
|
</taxonomicName>
|
|
or the early dinosaur
|
|
<taxonomicName id="4C75B4A2F05AFFA7FA95FC71FA2AFC4F" authorityName="Reig" authorityYear="1963" box="[1357,1495,931,951]" class="Reptilia" family="Herrerasauridae" genus="Herrerasaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05AFFA7FA95FC71FA2AFC4F" box="[1357,1495,931,951]" italics="true" pageId="1" pageNumber="27">Herrerasaurus</emphasis>
|
|
</taxonomicName>
|
|
, strengthening the hypothesis that this feature is unique to theropod taxa. The groove was also not observed in
|
|
<emphasis id="B9011333F05AFFA7FA98FC09FA21FC17" box="[1344,1500,987,1007]" italics="true" pageId="1" pageNumber="27">Daemonosaurus</emphasis>
|
|
or
|
|
<emphasis id="B9011333F05AFFA7FCB8FC25FC6EFBF3" box="[864,915,1015,1035]" italics="true" pageId="1" pageNumber="27">Tawa</emphasis>
|
|
, the most primitive true theropods that we sampled.
|
|
<emphasis id="B9011333F05AFFA7FCE7FBC1FBF1FBDF" box="[831,1036,1043,1063]" italics="true" pageId="1" pageNumber="27">
|
|
<taxonomicName id="4C75B4A2F05AFFA7FCE7FBC1FC58FBDF" authorityName="Marsh" authorityYear="1877" box="[831,933,1043,1063]" class="Reptilia" family="Allosauridae" genus="Allosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">Allosaurus</taxonomicName>
|
|
,
|
|
<taxonomicName id="4C75B4A2F05AFFA7FC69FBC1FBF1FBDF" authorityName="Charig & Milner" authorityYear="1986" box="[945,1036,1043,1063]" class="Reptilia" family="Spinosauridae" genus="Baryonyx" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">Baryonyx</taxonomicName>
|
|
</emphasis>
|
|
,
|
|
<taxonomicName id="4C75B4A2F05AFFA7FBC2FBC1FB3AFBDF" authorityName="Zhao & Currie" authorityYear="1993" box="[1050,1223,1043,1063]" class="Reptilia" genus="Monolophosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05AFFA7FBC2FBC1FB3AFBDF" box="[1050,1223,1043,1063]" italics="true" pageId="1" pageNumber="27">Monolophosaurus</emphasis>
|
|
</taxonomicName>
|
|
,
|
|
<emphasis id="B9011333F05AFFA7FB0DFBC1FA2AFBDF" box="[1237,1495,1043,1063]" italics="true" pageId="1" pageNumber="27">
|
|
<taxonomicName id="4C75B4A2F05AFFA7FB0DFBC1FAA8FBDF" authorityName="Osborn" authorityYear="1903" box="[1237,1365,1043,1063]" class="Reptilia" family="Compsognathidae" genus="Ornitholestes" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">Ornitholestes</taxonomicName>
|
|
,
|
|
<taxonomicName id="4C75B4A2F05AFFA7FABAFBC1FA2AFBDF" authorityName="Stromer" authorityYear="1915" box="[1378,1495,1043,1063]" class="Reptilia" family="Spinosauridae" genus="Spinosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">Spinosaurus</taxonomicName>
|
|
</emphasis>
|
|
, and
|
|
<taxonomicName id="4C75B4A2F05AFFA7FCB2FBFDFC22FBBB" authorityName="Galton & Jensen" authorityYear="1979" box="[874,991,1071,1091]" class="Reptilia" family="Megalosauridae" genus="Torvosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05AFFA7FCB2FBFDFC22FBBB" box="[874,991,1071,1091]" italics="true" pageId="1" pageNumber="27">Torvosaurus</emphasis>
|
|
</taxonomicName>
|
|
were the only observed pre-Tyrannoraptoran taxa that reverted to the primitive state (
|
|
<figureCitation id="134ED3A4F05AFFA7FB76FB9EFB19FBA7" box="[1198,1252,1100,1119]" captionStart="Fig" captionStartId="3.[113,138,1449,1463]" captionTargetBox="[127,1488,180,1419]" captionTargetId="figure@3.[125,1489,178,1420]" captionTargetPageId="3" captionText="Fig. 2. Cladogram of Theropoda modifed from Carrano et al. (2012). Thickened branches indicate lineages possessing the dentary groove, thin branches indicate lineages in which the groove is absent. Grayed-out braches marked with dashed lines indicate taxa without a known dentary. Circled numbers indicate sequence of losses of the dentary groove assuming maximum parsimony." figureDoi="http://doi.org/10.5281/zenodo.3890527" httpUri="https://zenodo.org/record/3890527/files/figure.png" pageId="1" pageNumber="27">Fig. 2</figureCitation>
|
|
).
|
|
</paragraph>
|
|
<paragraph id="8BCACF21F05AFFA7FC87FBBAFB20FA31" blockId="1.[831,1501,542,1733]" pageId="1" pageNumber="27">
|
|
The single most parsimonious tree recovered by our phylogenetic analysis of
|
|
<taxonomicName id="4C75B4A2F05AFFA7FC32FB56FB73FB6F" authorityName="Osborn" authorityYear="1906" box="[1002,1166,1156,1175]" class="Reptilia" family="Tyrannosauridae" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="33" phylum="Chordata" rank="family">tyrannosauridae</taxonomicName>
|
|
is reported in
|
|
<figureCitation id="134ED3A4F05AFFA7FAFFFB56FA93FB6F" box="[1319,1390,1156,1175]" captionStart="Fig" captionStartId="4.[88,113,1624,1638]" captionTargetBox="[222,1339,180,1594]" captionTargetId="figure@4.[221,1340,178,1595]" captionTargetPageId="4" captionText="Fig. 3. Proposed phylogenetic relationships of Nanotyrannus within Tyrannosauroidea with distribution of the theropod dentary groove on trees indicated with thickened bars. (A) Most parsimonious cladogram proposed by this study placing Nanotyrannus as sister to the Albertosaurinae.(B) Relationship sensu Currie (2003a) placing Nanotyrannus as sister to Tyrannosaurus. This tree requires 5 more independent losses of the dentary groove than the tree proposed in this study. (C) Relationship proposed by Brusatte et al. (2010) placing Nanotyrannus as a juvenile Tyrannosaurus. This tree requires 4 more independent losses than the tree proposed in this study and a loss of the dentary groove through ontogeny in Tyrannosaurus." figureDoi="http://doi.org/10.5281/zenodo.3890529" httpUri="https://zenodo.org/record/3890529/files/figure.png" pageId="1" pageNumber="27">Fig. 3A</figureCitation>
|
|
. The minimum tree length was found after 5 replicates, and the most parsimonious tree has a length of 561.
|
|
<taxonomicName id="4C75B4A2F05AFFA7FB66FB68FABAFB36" authority="Bakker et al., 1988" authorityName="Bakker et al." authorityYear="1988" box="[1214,1351,1210,1230]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05AFFA7FB66FB68FABAFB36" box="[1214,1351,1210,1230]" italics="true" pageId="1" pageNumber="27">Nanotyrannus</emphasis>
|
|
</taxonomicName>
|
|
was recovered as the sister taxon to the
|
|
<taxonomicName id="4C75B4A2F05AFFA7FB99FB05FB1EFB12" box="[1089,1251,1239,1258]" class="Reptilia" family="Tyrannosauridae" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="subFamily" subFamily="Albertosaurinae">Albertosaurinae</taxonomicName>
|
|
. We recovered the same topology as reported by
|
|
<bibRefCitation id="EFE4B2D0F05AFFA7FB91FB26FAD7FAFE" author="Brusatte, S. L. & Norell, M. A. & Carr, T. D. & Erickson, G. M. & Hutchinson, J. R. & Balanoff, A. M. & Bever, G. S. & Choiniere, J. N. & Makovicky, P. J. & Xu, X." box="[1097,1322,1267,1287]" journalOrPublisher="Science" pageId="1" pageNumber="27" pagination="1481 - 1485" part="329" refId="ref5776" refString="Brusatte, S. L., Norell, M. A., Carr, T. D., Erickson, G. M., Hutchinson, J. R., Balanoff, A. M., Bever, G. S., Choiniere, J. N., Makovicky, P. J., Xu, X., 2010. Tyrannosaur paleobiology: new research on ancient exemplar organisms. Science 329, 1481 - 1485." title="Tyrannosaur paleobiology: new research on ancient exemplar organisms" type="journal article" year="2010">Brusatte et al. (2010)</bibRefCitation>
|
|
, except that the
|
|
<taxonomicName id="4C75B4A2F05AFFA7FCE7FADDFC09FADA" box="[831,1012,1295,1314]" class="Reptilia" family="Proceratosauridae" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="family">Proceratosauridae</taxonomicName>
|
|
was recovered as a polytomy. The most parsimonious tree we produced resulted in a polytomy, regardless of whether
|
|
<taxonomicName id="4C75B4A2F05AFFA7FC7BFA94FBD1FAA2" authority="Bakker et al., 1988" authorityName="Bakker et al." authorityYear="1988" box="[931,1068,1350,1370]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05AFFA7FC7BFA94FBD1FAA2" box="[931,1068,1350,1370]" italics="true" pageId="1" pageNumber="27">Nanotyrannus</emphasis>
|
|
</taxonomicName>
|
|
was included or not. Alternative nonparsimonious tree topologies based on our result but reflecting the proposed relationships of
|
|
<taxonomicName id="4C75B4A2F05AFFA7FBAEFAAFFB02FA69" authority="Bakker et al., 1988" authorityName="Bakker et al." authorityYear="1988" box="[1142,1279,1405,1425]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="27" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05AFFA7FBAEFAAFFB02FA69" box="[1142,1279,1405,1425]" italics="true" pageId="1" pageNumber="27">Nanotyrannus</emphasis>
|
|
</taxonomicName>
|
|
among the Tyrannosauroidea
|
|
<emphasis id="B9011333F05AFFA7FC70FA4BFC23FA55" box="[936,990,1433,1453]" italics="true" pageId="1" pageNumber="27">sensu</emphasis>
|
|
<bibRefCitation id="EFE4B2D0F05AFFA7FC3EFA49FB86FA56" author="Currie, P. J." box="[998,1147,1435,1454]" journalOrPublisher="Acta Palaeontologica Polonica" pageId="1" pageNumber="27" pagination="191 - 226" part="48" refId="ref6096" refString="Currie, P. J., 2003 a. Cranial anatomy of tyrannosaurid dinosaus from the Late Cretaceous of Alberta, Canada. Acta Palaeontologica Polonica 48, 191 - 226." title="Cranial anatomy of tyrannosaurid dinosaus from the Late Cretaceous of Alberta, Canada" type="journal article" year="2003">Currie (2003a)</bibRefCitation>
|
|
and
|
|
<bibRefCitation id="EFE4B2D0F05AFFA7FB68FA49FAD9FA56" author="Carr, T. D." box="[1200,1316,1435,1454]" journalOrPublisher="Journal of Vertebrate Paleontology" pageId="1" pageNumber="27" pagination="497 - 520" part="19" refId="ref5906" refString="Carr, T. D., 1999. Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria). Journal of Vertebrate Paleontology 19, 497 - 520." title="Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria)" type="journal article" year="1999">Carr (1999)</bibRefCitation>
|
|
are presented for comparison in
|
|
<figureCitation id="134ED3A4F05AFFA7FC0EFA64FBA4FA32" box="[982,1113,1462,1482]" captionStart="Fig" captionStartId="4.[88,113,1624,1638]" captionTargetBox="[222,1339,180,1594]" captionTargetId="figure@4.[221,1340,178,1595]" captionTargetPageId="4" captionText="Fig. 3. Proposed phylogenetic relationships of Nanotyrannus within Tyrannosauroidea with distribution of the theropod dentary groove on trees indicated with thickened bars. (A) Most parsimonious cladogram proposed by this study placing Nanotyrannus as sister to the Albertosaurinae.(B) Relationship sensu Currie (2003a) placing Nanotyrannus as sister to Tyrannosaurus. This tree requires 5 more independent losses of the dentary groove than the tree proposed in this study. (C) Relationship proposed by Brusatte et al. (2010) placing Nanotyrannus as a juvenile Tyrannosaurus. This tree requires 4 more independent losses than the tree proposed in this study and a loss of the dentary groove through ontogeny in Tyrannosaurus." figureDoi="http://doi.org/10.5281/zenodo.3890529" httpUri="https://zenodo.org/record/3890529/files/figure.png" pageId="1" pageNumber="27">Fig. 3B and C</figureCitation>
|
|
respectively.
|
|
</paragraph>
|
|
<paragraph id="8BCACF21F05AFFA7FC87FA01FC77F93D" blockId="1.[831,1501,542,1733]" pageId="1" pageNumber="27">
|
|
We investigated undisputed
|
|
<taxonomicName id="4C75B4A2F05AFFA7FB57FA03FAB5FA1D" authorityName="Osborn" authorityYear="1905" box="[1167,1352,1489,1509]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="33" phylum="Chordata" rank="species" species="rex">
|
|
<emphasis id="B9011333F05AFFA7FB57FA03FAB5FA1D" box="[1167,1352,1489,1509]" italics="true" pageId="1" pageNumber="27">Tyrannosaurus rex</emphasis>
|
|
</taxonomicName>
|
|
material pertaining to the different life stages (i.e., juvenile, subadult, and adult of
|
|
<bibRefCitation id="EFE4B2D0F05AFFA7FC80F9D8FB95F9E5" author="Carr, T. D. & Williamson, T. E." box="[856,1128,1546,1565]" journalOrPublisher="Zoological Journal of the Linnean Society" pageId="1" pageNumber="27" pagination="479 - 523" part="142" refId="ref5935" refString="Carr, T. D., Williamson, T. E., 2004. Diversity of late Maastrichtian Tyrannosauridae (Dinosauria: Theropoda) from western North America. Zoological Journal of the Linnean Society 142, 479 - 523." title="Diversity of late Maastrichtian Tyrannosauridae (Dinosauria: Theropoda) from western North America" type="journal article" year="2004">Carr and Williamson, 2004</bibRefCitation>
|
|
). The dentary of the smallest known juvenile of
|
|
<taxonomicName id="4C75B4A2F05AFFA7FC77F9F7FC1FF9C1" authorityName="Osborn" authorityYear="1905" box="[943,994,1573,1593]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="33" phylum="Chordata" rank="species" species="rex">
|
|
<emphasis id="B9011333F05AFFA7FC77F9F7FC1FF9C1" box="[943,994,1573,1593]" italics="true" pageId="1" pageNumber="27">T. rex</emphasis>
|
|
</taxonomicName>
|
|
(LACM 28471) lacks the dentary groove. Although its dentary is fragmentary, the anterior portion is preserved, and examination failed to reveal the presence of a dentary groove. None of the
|
|
<taxonomicName id="4C75B4A2F05AFFA7FC61F9AAFC16F974" authorityName="Osborn" authorityYear="1905" box="[953,1003,1656,1676]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="33" phylum="Chordata" rank="species" species="rex">
|
|
<emphasis id="B9011333F05AFFA7FC61F9AAFC16F974" box="[953,1003,1656,1676]" italics="true" pageId="1" pageNumber="27">T. rex</emphasis>
|
|
</taxonomicName>
|
|
specimens examined (LACM 28471, LACM 23845, LACM 150167, KUVP 155809, FMNH PR2081) possessed the groove.
|
|
</paragraph>
|
|
</subSubSection>
|
|
<subSubSection id="C36F9CAAF05AFFA3FCE7F93BFBD9FA1D" lastPageId="5" lastPageNumber="31" pageId="1" pageNumber="27" type="description">
|
|
<paragraph id="8BCACF21F05AFFA7FCE7F93BFC33F904" blockId="1.[831,974,1769,1788]" box="[831,974,1769,1788]" pageId="1" pageNumber="27">
|
|
<heading id="D082784DF05AFFA7FCE7F93BFC33F904" bold="true" box="[831,974,1769,1788]" fontSize="8" level="2" pageId="1" pageNumber="27" reason="0">
|
|
<emphasis id="B9011333F05AFFA7FCE7F93BFC33F904" bold="true" box="[831,974,1769,1788]" pageId="1" pageNumber="27">4. Discussion</emphasis>
|
|
</heading>
|
|
</paragraph>
|
|
<paragraph id="8BCACF21F05AFFA7FCE7F8F2FB05F8CC" blockId="1.[831,1272,1824,1844]" box="[831,1272,1824,1844]" pageId="1" pageNumber="27">
|
|
<heading id="D082784DF05AFFA7FCE7F8F2FB05F8CC" bold="true" box="[831,1272,1824,1844]" fontSize="8" level="2" pageId="1" pageNumber="27" reason="0">
|
|
<emphasis id="B9011333F05AFFA7FCE7F8F2FB05F8CC" box="[831,1272,1824,1844]" italics="true" pageId="1" pageNumber="27">4.1. Discussion of presence of dentary groove</emphasis>
|
|
</heading>
|
|
</paragraph>
|
|
<paragraph id="8BCACF21F05AFFA5FC87F88BFB28F900" blockId="1.[831,1501,1881,1984]" lastBlockId="3.[831,1501,1598,1980]" lastPageId="3" lastPageNumber="29" pageId="1" pageNumber="27">
|
|
The dentary groove is present in 33 of 41 (80%) of the pre- Tyrannoraptoran theropods sampled here. We interpret only 6 reversals responsible for groove losses (
|
|
<figureCitation id="134ED3A4F05AFFA7FB1AF843FB04F85C" box="[1218,1273,1937,1956]" captionStart="Fig" captionStartId="3.[113,138,1449,1463]" captionTargetBox="[127,1488,180,1419]" captionTargetId="figure@3.[125,1489,178,1420]" captionTargetPageId="3" captionText="Fig. 2. Cladogram of Theropoda modifed from Carrano et al. (2012). Thickened branches indicate lineages possessing the dentary groove, thin branches indicate lineages in which the groove is absent. Grayed-out braches marked with dashed lines indicate taxa without a known dentary. Circled numbers indicate sequence of losses of the dentary groove assuming maximum parsimony." figureDoi="http://doi.org/10.5281/zenodo.3890527" httpUri="https://zenodo.org/record/3890527/files/figure.png" pageId="1" pageNumber="27">Fig. 2</figureCitation>
|
|
). The presence of this groove is therefore a character primitive for nearly all early theropods. Given the absence of the groove in the theropod clades which include
|
|
<emphasis id="B9011333F058FFA5FEDCF98BFE5DF995" box="[260,416,1625,1645]" italics="true" pageId="3" pageNumber="29">Daemonosaurus</emphasis>
|
|
and
|
|
<emphasis id="B9011333F058FFA5FE17F98BFDFFF995" box="[463,514,1625,1645]" italics="true" pageId="3" pageNumber="29">Tawa</emphasis>
|
|
, the groove first evolved in the earliest common ancestor of the Neotheropoda. Within highly derived theropods, the dentary groove is present in some members of the Maniraptora. A similar foramina-bearing groove has been considered a synapomophy of
|
|
<taxonomicName id="4C75B4A2F058FFA5FD50F91BFE60F900" authority="(Makovicky and Norell, 2004)" baseAuthorityName="Makovicky and Norell" baseAuthorityYear="2004" class="Reptilia" family="Troodontidae" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="29" phylum="Chordata" rank="family">
|
|
Troodontidae (
|
|
<bibRefCitation id="EFE4B2D0F058FFA5FFA1F937FE6EF901" author="Makovicky, P. J. & Norell, M. A." box="[121,403,1765,1785]" editor="Weishampel, D. B. & Dodson, P. & Osmolska, H." journalOrPublisher="University of California Press, Los Angeles, California" pageId="3" pageNumber="29" pagination="184 - 195" refId="ref7108" refString="Makovicky, P. J., Norell, M. A., 2004. Troodontidae. In: Weishampel, D. B., Dodson, P., Osmolska, H. (Eds.), The Dinosauria. University of California Press, Los Angeles, California, pp. 184 - 195." title="Troodontidae" type="book chapter" volumeTitle="The Dinosauria" year="2004">Makovicky and Norell, 2004</bibRefCitation>
|
|
)
|
|
</taxonomicName>
|
|
. As such, it is present on all sampled troodontids, but limited to the posterior portion of the dentary. A groove was also observed in the dromaeosaurids
|
|
<taxonomicName id="4C75B4A2F058FFA5FD55F8CEFCF7F8C8" authorityName="Evans, Larson & Currie" authorityYear="2013" box="[653,778,1820,1840]" class="Reptilia" family="Dromaeosauridae" genus="Acheroraptor" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="29" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F058FFA5FD55F8CEFCF7F8C8" box="[653,778,1820,1840]" italics="true" pageId="3" pageNumber="29">Acheroraptor</emphasis>
|
|
</taxonomicName>
|
|
,
|
|
<taxonomicName id="4C75B4A2F058FFA5FFA9F8EAFF11F8B4" authorityName="Novas, Pol, Canale, Porfiri & Calvo" authorityYear="2008" box="[113,236,1848,1868]" class="Reptilia" family="Dromaeosauridae" genus="Austroraptor" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="29" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F058FFA5FFA9F8EAFF11F8B4" box="[113,236,1848,1868]" italics="true" pageId="3" pageNumber="29">Austroraptor</emphasis>
|
|
</taxonomicName>
|
|
and
|
|
<taxonomicName id="4C75B4A2F058FFA5FEC3F8EAFE6DF8B4" authorityName="Makovicky, Apesteguia & Agnolin" authorityYear="2005" box="[283,400,1848,1868]" class="Reptilia" family="Dromaeosauridae" genus="Buitreraptor" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="29" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F058FFA5FEC3F8EAFE6DF8B4" box="[283,400,1848,1868]" italics="true" pageId="3" pageNumber="29">Buitreraptor</emphasis>
|
|
</taxonomicName>
|
|
. In Maniraptora, the groove appears to increase in height posteriorly (i.e., grows closer to the tooth row), creating a wedge-shaped appearance, rather than the linear shape of the groove in other theropod dinosaurs. In the troodontids,
|
|
<taxonomicName id="4C75B4A2F058FFA5FFA9F875FF13F843" authorityName="Evans, Larson & Currie" authorityYear="2013" box="[113,238,1959,1979]" class="Reptilia" family="Dromaeosauridae" genus="Acheroraptor" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="29" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F058FFA5FFA9F875FF13F843" box="[113,238,1959,1979]" italics="true" pageId="3" pageNumber="29">Acheroraptor</emphasis>
|
|
</taxonomicName>
|
|
, and
|
|
<taxonomicName id="4C75B4A2F058FFA5FEF2F875FE5EF843" authorityName="Novas, Pol, Canale, Porfiri & Calvo" authorityYear="2008" box="[298,419,1959,1979]" class="Reptilia" family="Dromaeosauridae" genus="Austroraptor" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="29" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F058FFA5FEF2F875FE5EF843" box="[298,419,1959,1979]" italics="true" pageId="3" pageNumber="29">Austroraptor</emphasis>
|
|
</taxonomicName>
|
|
, the groove originates beneath the middle of the tooth row and extends nearly to the posterior end of the dentary. We interpret this difference as truly morphological and do not consider the groove found in the Maniraptora to be homologous with the dentary groove of other theropods.
|
|
<bibRefCitation id="EFE4B2D0F058FFA5FA46F940FC7DF939" author="Currie, P. J." journalOrPublisher="Journal of Vertebrate Paleontology" pageId="3" pageNumber="29" pagination="72 - 81" part="7" refId="ref6061" refString="Currie, P. J., 1987. Bird-like characteristics of the jaws and teeth of troodontid theropods (Dinosauria, Saurischia). Journal of Vertebrate Paleontology 7, 72 - 81." title="Bird-like characteristics of the jaws and teeth of troodontid theropods (Dinosauria, Saurischia)" type="journal article" year="1987">Currie (1987)</bibRefCitation>
|
|
and
|
|
<bibRefCitation id="EFE4B2D0F058FFA5FC6EF97CFB1CF939" author="Makovicky, P. J. & Norell, M. A." box="[950,1249,1710,1729]" editor="Weishampel, D. B. & Dodson, P. & Osmolska, H." journalOrPublisher="University of California Press, Los Angeles, California" pageId="3" pageNumber="29" pagination="184 - 195" refId="ref7108" refString="Makovicky, P. J., Norell, M. A., 2004. Troodontidae. In: Weishampel, D. B., Dodson, P., Osmolska, H. (Eds.), The Dinosauria. University of California Press, Los Angeles, California, pp. 184 - 195." title="Troodontidae" type="book chapter" volumeTitle="The Dinosauria" year="2004">Makovicky and Norell (2004)</bibRefCitation>
|
|
have interpreted a neurovascular function for this troodontid groove and its pores, an interpretation that we do not challenge.
|
|
</paragraph>
|
|
<caption id="DF0A9FA9F059FFA4FF80F93FFCC3F8B8" ID-DOI="http://doi.org/10.5281/zenodo.3890525" ID-Zenodo-Dep="3890525" httpUri="https://zenodo.org/record/3890525/files/figure.png" pageId="2" pageNumber="28" startId="2.[88,113,1773,1787]" targetBox="[101,1462,304,1744]" targetPageId="2">
|
|
<paragraph id="8BCACF21F059FFA4FF80F93FFCC3F8B8" blockId="2.[88,1475,1773,1856]" pageId="2" pageNumber="28">
|
|
<emphasis id="B9011333F059FFA4FF80F93FFF7BF903" bold="true" box="[88,134,1773,1787]" pageId="2" pageNumber="28">Fig. 1.</emphasis>
|
|
Lateral views of theropod skulls demonstrating presence or absence of the dentary groove. The dentary groove is present in the primitive theropod (
|
|
<emphasis id="B9011333F059FFA4FAFFF93FFACFF903" bold="true" box="[1319,1330,1773,1787]" pageId="2" pageNumber="28">A</emphasis>
|
|
)
|
|
<emphasis id="B9011333F059FFA4FAE6F93FFA3FF904" box="[1342,1474,1773,1788]" italics="true" pageId="2" pageNumber="28">Coelophysis bauri</emphasis>
|
|
(NMMNH P-42200), as well as in the derived theropod (
|
|
<emphasis id="B9011333F059FFA4FDDFF8D6FDEFF8EA" bold="true" box="[519,530,1796,1810]" pageId="2" pageNumber="28">B</emphasis>
|
|
)
|
|
<emphasis id="B9011333F059FFA4FDC4F8D1FD2EF8EB" box="[540,723,1795,1811]" italics="true" pageId="2" pageNumber="28">
|
|
<taxonomicName id="4C75B4A2F059FFA4FDC4F8D1FD6FF8EA" authorityName="Wagner" authorityYear="1859" box="[540,658,1795,1810]" class="Reptilia" family="Compsognathidae" genus="Compsognathus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="2" pageNumber="28" phylum="Chordata" rank="genus">Compsognathus</taxonomicName>
|
|
longipes
|
|
</emphasis>
|
|
(BSP AS I 563). The dentary groove is present in the tyrannosaurids (
|
|
<emphasis id="B9011333F059FFA4FB3DF8D6FB12F8EA" bold="true" box="[1253,1263,1796,1810]" pageId="2" pageNumber="28">C</emphasis>
|
|
)
|
|
<emphasis id="B9011333F059FFA4FB22F8D1FA69F8EB" box="[1274,1428,1795,1811]" italics="true" pageId="2" pageNumber="28">
|
|
<taxonomicName id="4C75B4A2F059FFA4FB22F8D1FAA5F8EA" baseAuthorityName="Gilmore" baseAuthorityYear="1946" box="[1274,1368,1795,1810]" class="Reptilia" family="Tyrannosauridae" genus="Gorgosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="2" pageNumber="28" phylum="Chordata" rank="genus">Gorgosaurus</taxonomicName>
|
|
libratus
|
|
</emphasis>
|
|
(TCM 2001.89.1) and (
|
|
<emphasis id="B9011333F059FFA4FF0EF8C9FF1FF8D1" bold="true" box="[214,226,1819,1833]" pageId="2" pageNumber="28">D</emphasis>
|
|
)
|
|
<emphasis id="B9011333F059FFA4FF36F8C8FE5CF8D1" box="[238,417,1818,1833]" italics="true" pageId="2" pageNumber="28">
|
|
<taxonomicName id="4C75B4A2F059FFA4FF36F8C8FEA5F8D1" authority="Bakker et al., 1988" authorityName="Bakker et al." authorityYear="1988" box="[238,344,1818,1833]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="2" pageNumber="28" phylum="Chordata" rank="genus">Nanotyrannus</taxonomicName>
|
|
lancensis
|
|
</emphasis>
|
|
(“Jane”; BMR P2002.4.1). The dentary groove is absent in both (
|
|
<emphasis id="B9011333F059FFA4FC43F8C9FC58F8D1" bold="true" box="[923,933,1819,1833]" pageId="2" pageNumber="28">E</emphasis>
|
|
<emphasis id="B9011333F059FFA4FC7DF8F0FC51F8D4" bold="true" box="[933,940,1826,1836]" pageId="2" pageNumber="28">
|
|
<subScript id="17F1CD64F059FFA4FC7DF8F0FC51F8D4" attach="left" box="[933,940,1826,1836]" fontSize="4" pageId="2" pageNumber="28">1</subScript>
|
|
</emphasis>
|
|
) young (LACM 28471) and (
|
|
<emphasis id="B9011333F059FFA4FB53F8C9FB68F8D1" bold="true" box="[1163,1173,1819,1833]" pageId="2" pageNumber="28">E</emphasis>
|
|
<emphasis id="B9011333F059FFA4FB4EF8F0FB60F8D4" bold="true" box="[1174,1181,1826,1836]" pageId="2" pageNumber="28">
|
|
<subScript id="17F1CD64F059FFA4FB4EF8F0FB60F8D4" attach="right" box="[1174,1181,1826,1836]" fontSize="4" pageId="2" pageNumber="28">2</subScript>
|
|
</emphasis>
|
|
) adult (“Sue”; FMNH PR2081)
|
|
<taxonomicName id="4C75B4A2F059FFA4FA49F8C8FF45F8B8" authorityName="Osborn" authorityYear="1905" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="2" pageNumber="33" phylum="Chordata" rank="species" species="rex">
|
|
<emphasis id="B9011333F059FFA4FA49F8C8FF45F8B8" italics="true" pageId="2" pageNumber="28">Tyrannosaurus rex</emphasis>
|
|
</taxonomicName>
|
|
. Arrows indicate the position of the groove, when present. Scale bars equal 5 cm.
|
|
</paragraph>
|
|
</caption>
|
|
<caption id="DF0A9FA9F058FFA5FFA9FA7BFE90FA1D" ID-DOI="http://doi.org/10.5281/zenodo.3890527" ID-Zenodo-Dep="3890527" httpUri="https://zenodo.org/record/3890527/files/figure.png" pageId="3" pageNumber="29" startId="3.[113,138,1449,1463]" targetBox="[127,1488,180,1419]" targetPageId="3">
|
|
<paragraph id="8BCACF21F058FFA5FFA9FA7BFE90FA1D" blockId="3.[113,1500,1449,1509]" pageId="3" pageNumber="29">
|
|
<emphasis id="B9011333F058FFA5FFA9FA7BFF5CFA4F" bold="true" box="[113,161,1449,1463]" pageId="3" pageNumber="29">Fig. 2.</emphasis>
|
|
Cladogram of Theropoda modifed from
|
|
<bibRefCitation id="EFE4B2D0F058FFA5FE06FA78FD80FA40" author="Carrano, M. T. & Benson, R. B. J. & Sampson, S. D." box="[478,637,1450,1464]" journalOrPublisher="Journal of Systematic Palaeontology" pageId="3" pageNumber="29" pagination="211 - 300" part="10" refId="ref5978" refString="Carrano, M. T., Benson, R. B. J., Sampson, S. D., 2012. The phylogeny of Tetanurae (Dinosauria: Theropoda). Journal of Systematic Palaeontology 10, 211 - 300." title="The phylogeny of Tetanurae (Dinosauria: Theropoda)" type="journal article" year="2012">Carrano et al. (2012)</bibRefCitation>
|
|
. Thickened branches indicate lineages possessing the dentary groove, thin branches indicate lineages in which the groove is absent. Grayed-out braches marked with dashed lines indicate taxa without a known dentary. Circled numbers indicate sequence of losses of the dentary groove assuming maximum parsimony.
|
|
</paragraph>
|
|
</caption>
|
|
<paragraph id="8BCACF21F058FFA5FC87F8D0FBFFF844" blockId="3.[831,1501,1598,1980]" pageId="3" pageNumber="29">
|
|
Few tyrannosauroids retain this groove. “Jane” clearly has this groove (
|
|
<figureCitation id="134ED3A4F058FFA5FC4EF8CFFC1DF8C8" box="[918,992,1821,1840]" captionStart="Fig" captionStartId="2.[88,113,1773,1787]" captionTargetBox="[101,1462,304,1744]" captionTargetId="figure@2.[101,1462,304,1744]" captionTargetPageId="2" captionText="Fig. 1. Lateral views of theropod skulls demonstrating presence or absence of the dentary groove. The dentary groove is present in the primitive theropod (A) Coelophysis bauri (NMMNH P-42200), as well as in the derived theropod (B) Compsognathus longipes (BSP AS I 563). The dentary groove is present in the tyrannosaurids (C) Gorgosaurus libratus (TCM 2001.89.1) and (D) Nanotyrannus lancensis (“Jane”; BMR P2002.4.1). The dentary groove is absent in both (E1) young (LACM 28471) and (E2) adult (“Sue”; FMNH PR2081) Tyrannosaurus rex. Arrows indicate the position of the groove, when present. Scale bars equal 5 cm." figureDoi="http://doi.org/10.5281/zenodo.3890525" httpUri="https://zenodo.org/record/3890525/files/figure.png" pageId="3" pageNumber="29">Fig. 1D</figureCitation>
|
|
) as does
|
|
<materialsCitation id="3B1DC57CF058FFA5FB93F8CCFB51F8C8" ID-GBIF-Occurrence="2960701306" box="[1099,1196,1821,1841]" collectionCode="BHI" pageId="3" pageNumber="29" specimenCode="BHI 6437">BHI 6437</materialsCitation>
|
|
. The condition of the
|
|
<taxonomicName id="4C75B4A2F058FFA5FA78F8CEFC68F8B4" authority="Bakker et al., 1988" authorityName="Bakker et al." authorityYear="1988" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="29" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F058FFA5FA78F8CEFC68F8B4" italics="true" pageId="3" pageNumber="29">Nanotyrannus</emphasis>
|
|
</taxonomicName>
|
|
holotype is unclear, as its jaws are occluded and the groove-bearing portion of the dentary obscured. The only other tyrannosauroids that possess this groove are
|
|
<emphasis id="B9011333F058FFA5FAC4F8A2FC78F867" italics="true" pageId="3" pageNumber="29">Dryptosaurus aquilunguis</emphasis>
|
|
and the
|
|
<taxonomicName id="4C75B4A2F058FFA5FC39F85FFB78F858" box="[993,1157,1933,1952]" class="Reptilia" family="Tyrannosauridae" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="29" phylum="Chordata" rank="subFamily" subFamily="Albertosaurinae">Albertosaurinae</taxonomicName>
|
|
:
|
|
<emphasis id="B9011333F058FFA5FB48F859FAA4F867" box="[1168,1369,1931,1951]" italics="true" pageId="3" pageNumber="29">
|
|
<taxonomicName id="4C75B4A2F058FFA5FB48F859FAF7F867" baseAuthorityName="Gilmore" baseAuthorityYear="1946" box="[1168,1290,1931,1951]" class="Reptilia" family="Tyrannosauridae" genus="Gorgosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="29" phylum="Chordata" rank="genus">Gorgosaurus</taxonomicName>
|
|
libratus
|
|
</emphasis>
|
|
and
|
|
<emphasis id="B9011333F058FFA5FA56F859FC00F843" italics="true" pageId="3" pageNumber="29">
|
|
<taxonomicName id="4C75B4A2F058FFA5FA56F859FC82F843" authorityName="Osborn" authorityYear="1905" class="Reptilia" family="Tyrannosauridae" genus="Albertosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="3" pageNumber="29" phylum="Chordata" rank="genus">Albertosaurus</taxonomicName>
|
|
sarcophagus
|
|
</emphasis>
|
|
.
|
|
</paragraph>
|
|
<caption id="DF0A9FA9F05FFFA2FF80F98AFF37F93A" ID-DOI="http://doi.org/10.5281/zenodo.3890529" ID-Zenodo-Dep="3890529" httpUri="https://zenodo.org/record/3890529/files/figure.png" pageId="4" pageNumber="30" startId="4.[88,113,1624,1638]" targetBox="[222,1339,180,1594]" targetPageId="4">
|
|
<paragraph id="8BCACF21F05FFFA2FF80F98AFF37F93A" blockId="4.[88,1475,1624,1730]" pageId="4" pageNumber="30">
|
|
<emphasis id="B9011333F05FFFA2FF80F98AFF7AF99E" bold="true" box="[88,135,1624,1638]" pageId="4" pageNumber="30">Fig. 3.</emphasis>
|
|
Proposed phylogenetic relationships of
|
|
<taxonomicName id="4C75B4A2F05FFFA2FE19F98AFDD6F99F" authority="Bakker et al., 1988" authorityName="Bakker et al." authorityYear="1988" box="[449,555,1624,1639]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="30" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05FFFA2FE19F98AFDD6F99F" box="[449,555,1624,1639]" italics="true" pageId="4" pageNumber="30">Nanotyrannus</emphasis>
|
|
</taxonomicName>
|
|
within Tyrannosauroidea with distribution of the theropod dentary groove on trees indicated with thickened bars. (
|
|
<emphasis id="B9011333F05FFFA2FA69F98AFA41F99E" bold="true" box="[1457,1468,1624,1638]" pageId="4" pageNumber="30">A</emphasis>
|
|
) Most parsimonious cladogram proposed by this study placing
|
|
<taxonomicName id="4C75B4A2F05FFFA2FDE2F9BCFD59F985" authority="Bakker et al., 1988" authorityName="Bakker et al." authorityYear="1988" box="[570,676,1646,1661]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="30" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05FFFA2FDE2F9BCFD59F985" box="[570,676,1646,1661]" italics="true" pageId="4" pageNumber="30">Nanotyrannus</emphasis>
|
|
</taxonomicName>
|
|
as sister to the
|
|
<taxonomicName id="4C75B4A2F05FFFA2FCC5F9BDFC67F985" box="[797,922,1647,1661]" class="Reptilia" family="Tyrannosauridae" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="30" phylum="Chordata" rank="subFamily" subFamily="Albertosaurinae">Albertosaurinae</taxonomicName>
|
|
. (
|
|
<emphasis id="B9011333F05FFFA2FC7FF9BDFC4FF985" bold="true" box="[935,946,1647,1661]" pageId="4" pageNumber="30">B</emphasis>
|
|
) Relationship
|
|
<emphasis id="B9011333F05FFFA2FBF9F9BCFBB7F985" box="[1057,1098,1646,1661]" italics="true" pageId="4" pageNumber="30">sensu</emphasis>
|
|
<bibRefCitation id="EFE4B2D0F05FFFA2FB97F9BDFB3CF985" author="Currie, P. J." box="[1103,1217,1647,1661]" journalOrPublisher="Acta Palaeontologica Polonica" pageId="4" pageNumber="30" pagination="191 - 226" part="48" refId="ref6096" refString="Currie, P. J., 2003 a. Cranial anatomy of tyrannosaurid dinosaus from the Late Cretaceous of Alberta, Canada. Acta Palaeontologica Polonica 48, 191 - 226." title="Cranial anatomy of tyrannosaurid dinosaus from the Late Cretaceous of Alberta, Canada" type="journal article" year="2003">Currie (2003a)</bibRefCitation>
|
|
placing
|
|
<taxonomicName id="4C75B4A2F05FFFA2FAD9F9BCFA96F985" authority="Bakker et al., 1988" authorityName="Bakker et al." authorityYear="1988" box="[1281,1387,1646,1661]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="30" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05FFFA2FAD9F9BCFA96F985" box="[1281,1387,1646,1661]" italics="true" pageId="4" pageNumber="30">Nanotyrannus</emphasis>
|
|
</taxonomicName>
|
|
as sister to
|
|
<taxonomicName id="4C75B4A2F05FFFA2FF80F957FF3BF96C" authorityName="Osborn" authorityYear="1905" box="[88,198,1669,1684]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="30" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05FFFA2FF80F957FF3BF96C" box="[88,198,1669,1684]" italics="true" pageId="4" pageNumber="30">Tyrannosaurus</emphasis>
|
|
</taxonomicName>
|
|
. This tree requires 5 more independent losses of the dentary groove than the tree proposed in this study. (
|
|
<emphasis id="B9011333F05FFFA2FBDDF954FBF2F96C" bold="true" box="[1029,1039,1670,1684]" pageId="4" pageNumber="30">C</emphasis>
|
|
) Relationship proposed by
|
|
<bibRefCitation id="EFE4B2D0F05FFFA2FB3CF954FA78F96C" author="Brusatte, S. L. & Norell, M. A. & Carr, T. D. & Erickson, G. M. & Hutchinson, J. R. & Balanoff, A. M. & Bever, G. S. & Choiniere, J. N. & Makovicky, P. J. & Xu, X." box="[1252,1413,1670,1684]" journalOrPublisher="Science" pageId="4" pageNumber="30" pagination="1481 - 1485" part="329" refId="ref5776" refString="Brusatte, S. L., Norell, M. A., Carr, T. D., Erickson, G. M., Hutchinson, J. R., Balanoff, A. M., Bever, G. S., Choiniere, J. N., Makovicky, P. J., Xu, X., 2010. Tyrannosaur paleobiology: new research on ancient exemplar organisms. Science 329, 1481 - 1485." title="Tyrannosaur paleobiology: new research on ancient exemplar organisms" type="journal article" year="2010">Brusatte et al. (2010)</bibRefCitation>
|
|
placing
|
|
<taxonomicName id="4C75B4A2F05FFFA2FF80F94EFF3FF953" authority="Bakker et al., 1988" authorityName="Bakker et al." authorityYear="1988" box="[88,194,1692,1707]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="30" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05FFFA2FF80F94EFF3FF953" box="[88,194,1692,1707]" italics="true" pageId="4" pageNumber="30">Nanotyrannus</emphasis>
|
|
</taxonomicName>
|
|
as a juvenile
|
|
<taxonomicName id="4C75B4A2F05FFFA2FEF3F94EFE64F953" authorityName="Osborn" authorityYear="1905" box="[299,409,1692,1707]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="30" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05FFFA2FEF3F94EFE64F953" box="[299,409,1692,1707]" italics="true" pageId="4" pageNumber="30">Tyrannosaurus</emphasis>
|
|
</taxonomicName>
|
|
. This tree requires 4 more independent losses than the tree proposed in this study and a loss of the dentary groove through ontogeny in
|
|
<taxonomicName id="4C75B4A2F05FFFA2FF80F961FF3BF93A" authorityName="Osborn" authorityYear="1905" box="[88,198,1715,1730]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="30" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05FFFA2FF80F961FF3BF93A" box="[88,198,1715,1730]" italics="true" pageId="4" pageNumber="30">Tyrannosaurus</emphasis>
|
|
</taxonomicName>
|
|
.
|
|
</paragraph>
|
|
</caption>
|
|
<paragraph id="8BCACF21F05FFFA2FF80F929FF59F8D3" blockId="4.[88,715,1787,1835]" pageId="4" pageNumber="30">
|
|
<heading id="D082784DF05FFFA2FF80F929FF59F8D3" bold="true" fontSize="8" level="2" pageId="4" pageNumber="30" reason="0">
|
|
<emphasis id="B9011333F05FFFA2FF80F929FF59F8D3" italics="true" pageId="4" pageNumber="30">4.2. Possible implications of beak formation and dentary groove absence</emphasis>
|
|
</heading>
|
|
</paragraph>
|
|
<paragraph id="8BCACF21F05FFFA3FFAFF882FEFAFECE" blockId="4.[88,757,1872,1975]" lastBlockId="5.[113,783,179,952]" lastPageId="5" lastPageNumber="31" pageId="4" pageNumber="30">
|
|
There are several dentary groove absences that occur simultaneously with the presence of a beak or edentulous jaws. The beaked ceratosaur
|
|
<emphasis id="B9011333F05FFFA2FF11F854FEC4F862" box="[201,313,1926,1946]" italics="true" pageId="4" pageNumber="30">Limusaurus</emphasis>
|
|
, ornithomimids (
|
|
<taxonomicName id="4C75B4A2F05FFFA2FE36F854FD80F862" box="[494,637,1926,1946]" class="Reptilia" family="Compsognathidae" genus="Nqwebasaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="30" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05FFFA2FE36F854FD80F862" box="[494,637,1926,1946]" italics="true" pageId="4" pageNumber="30">Nqwebasaurus</emphasis>
|
|
</taxonomicName>
|
|
and
|
|
<emphasis id="B9011333F05FFFA2FD6CF854FF41F84E" italics="true" pageId="4" pageNumber="30">Shenzhousaurus</emphasis>
|
|
), therizinosaurs (
|
|
<emphasis id="B9011333F05FFFA2FE59F870FE05F84E" box="[385,504,1954,1974]" italics="true" pageId="4" pageNumber="30">Erlikosaurus</emphasis>
|
|
and
|
|
<emphasis id="B9011333F05FFFA2FDE6F870FD15F84E" box="[574,744,1954,1974]" italics="true" pageId="4" pageNumber="30">Jiangchanosaurus</emphasis>
|
|
), oviraptorosaurs (
|
|
<taxonomicName id="4C75B4A2F05FFFA2FC0DF929FBB7F8F7" box="[981,1098,1787,1807]" class="Reptilia" family="Caudipterygidae" genus="Caudipteryx" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="30" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05FFFA2FC0DF929FBB7F8F7" box="[981,1098,1787,1807]" italics="true" pageId="4" pageNumber="30">Caudipteryx</emphasis>
|
|
</taxonomicName>
|
|
and
|
|
<taxonomicName id="4C75B4A2F05FFFA2FB5DF929FAFAF8F7" authorityName="Gilmore" authorityYear="1924" box="[1157,1287,1787,1807]" class="Reptilia" family="Caenagnathidae" genus="Chirostenotes" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="4" pageNumber="30" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05FFFA2FB5DF929FAFAF8F7" box="[1157,1287,1787,1807]" italics="true" pageId="4" pageNumber="30">Chirostenotes</emphasis>
|
|
</taxonomicName>
|
|
) and all sampled birds lack the dentary groove. The jaw structure of
|
|
<emphasis id="B9011333F05FFFA2FAF2F8C5FA67F8D3" box="[1322,1434,1815,1835]" italics="true" pageId="4" pageNumber="30">Limusaurus</emphasis>
|
|
has been completely modified into a beak and the dentary of
|
|
<emphasis id="B9011333F05FFFA2FA51F8E1FC98F89B" italics="true" pageId="4" pageNumber="30">Limusaurus</emphasis>
|
|
even lacks any foramina on its lateral surface. Simply modifying the mandible into a beak, however, does not account for this absence of the groove. Only the anterior of the upper jaws were beak-like in
|
|
<emphasis id="B9011333F05FFFA2FC7AF870FBB1F84E" box="[930,1100,1954,1974]" italics="true" pageId="4" pageNumber="30">Jiangchanosaurus</emphasis>
|
|
, in which only the premaxillae were considered to have been covered by a rhamphotheca (
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FD6AFF66FF5CFF1A" author="Pu, H. & Kobayashi, Y. & Lu, J. & Xu, L. & Wu, Y. & Chang, H. & Zhang, J. & Jia, S." journalOrPublisher="PLoS One" pageId="5" pageNumber="31" pagination="e 63423" part="5" refId="ref7581" refString="Pu, H., Kobayashi, Y., Lu, J., Xu, L., Wu, Y., Chang, H., Zhang, J., Jia, S., 2013. An unusual basal therizinosaur dinosaur with an ornithischian dental arrangement from northeastern China. PLoS One 5, e 63423." title="An unusual basal therizinosaur dinosaur with an ornithischian dental arrangement from northeastern China" type="journal article" year="2013">Pu et al., 2013</bibRefCitation>
|
|
).
|
|
<emphasis id="B9011333F05EFFA3FF65FF1CFE9AFF1A" box="[189,359,206,226]" italics="true" pageId="5" pageNumber="31">Jiangchanosaurus</emphasis>
|
|
does not have a groove. The toothed birds
|
|
<emphasis id="B9011333F05EFFA3FF76FF38FEC4FF06" box="[174,313,234,254]" italics="true" pageId="5" pageNumber="31">Archaeopteryx</emphasis>
|
|
,
|
|
<emphasis id="B9011333F05EFFA3FE90FF38FE46FF06" box="[328,443,234,254]" italics="true" pageId="5" pageNumber="31">Hesperornis</emphasis>
|
|
,
|
|
<emphasis id="B9011333F05EFFA3FE12FF38FDCBFF06" box="[458,566,234,254]" italics="true" pageId="5" pageNumber="31">Ichthyornis</emphasis>
|
|
, and
|
|
<emphasis id="B9011333F05EFFA3FDACFF38FCF2FF06" box="[628,783,234,254]" italics="true" pageId="5" pageNumber="31">Parahesperornis</emphasis>
|
|
also lack a dentary groove, despite being beakless or only having an incipient beak.
|
|
</paragraph>
|
|
<paragraph id="8BCACF21F05EFFA3FF49FEEDFCFCFC40" blockId="5.[113,783,179,952]" pageId="5" pageNumber="31">
|
|
Adoption of herbivory is a reasonable hypothesis for the evolutionary loss of serrated teeth from the jaws in favor of edentulous jaws or beaks. One explanation is that that the dentary groove played a role in predatory behavior and that the groove was lost in these theropods because carnivory was abandoned. Ornithomimids (
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FF29FE18FE28FE25" author="Kobayashi, Y. & Lu, J. - C. & Dong, Z. - M. & Barsbold, R. & Azuma, Y. & Tomida, Y." box="[241,469,458,478]" journalOrPublisher="Nature" pageId="5" pageNumber="31" pagination="480 - 481" part="402" refId="ref6834" refString="Kobayashi, Y., Lu, J. - C., Dong, Z. - M., Barsbold, R., Azuma, Y., Tomida, Y., 1999. Herbivorous diet in an ornithomimid dinosaur. Nature 402, 480 - 481." title="Herbivorous diet in an ornithomimid dinosaur" type="journal article" year="1999">Kobayashi et al., 1999</bibRefCitation>
|
|
;
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FE3AFE18FD60FE25" author="Norell, M. A. & Makovicky, P. J. & Currie, P. J." box="[482,669,458,478]" journalOrPublisher="Nature" pageId="5" pageNumber="31" pagination="873 - 874" part="12" refId="ref7309" refString="Norell, M. A., Makovicky, P. J., Currie, P. J., 2001. The beaks of ostrich dinosaurs. Nature 12, 873 - 874." title="The beaks of ostrich dinosaurs" type="journal article" year="2001">Norell et al., 2001</bibRefCitation>
|
|
) and therizinosaurs (
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FF30FE35FE59FE01" author="Zanno, L. E. & Gillette, D. D. & Albright, L. B. & Titus, A. L." box="[232,420,486,506]" journalOrPublisher="Proceedings of the Royal Society B" pageId="5" pageNumber="31" pagination="3305 - 3511" part="276" refId="ref8146" refString="Zanno, L. E., Gillette, D. D., Albright, L. B., Titus, A. L., 2009. A new North American therizinosaurid and the role of herbivory in ' predatory' dinosaur evolution. Proceedings of the Royal Society B 276, 3305 - 3511." title="A new North American therizinosaurid and the role of herbivory in ' predatory' dinosaur evolution" type="journal article" year="2009">Zanno et al., 2009</bibRefCitation>
|
|
) are both postulated to have been herbivorous. Oviraptorosaurs may have been predominately herbivorous (
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FF00FDCCFE9DFDC9" author="Ji, Q. & Currie, P. J. & Norell, M. A. & Ji, S." box="[216,352,542,561]" journalOrPublisher="Nature" pageId="5" pageNumber="31" pagination="753 - 761" part="393" refId="ref6794" refString="Ji, Q., Currie, P. J., Norell, M. A., Ji, S., 1998. Two feathered dinosaurs from northeastern China. Nature 393, 753 - 761." title="Two feathered dinosaurs from northeastern China" type="journal article" year="1998">Ji et al., 1998</bibRefCitation>
|
|
;
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FEB3FDCCFDFCFDC9" author="Xu, X. & Cheng, Y. & Wang, X. & Chang, C." box="[363,513,542,561]" journalOrPublisher="Nature" pageId="5" pageNumber="31" pagination="291 - 293" part="419" refId="ref8110" refString="Xu, X., Cheng, Y., Wang, X., Chang, C., 2002. An unusual oviraptorosaurian dinosaur from China. Nature 419, 291 - 293." title="An unusual oviraptorosaurian dinosaur from China" type="journal article" year="2002">Xu et al., 2002</bibRefCitation>
|
|
), although they may have taken prey or scavenged under rare circumstances (
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FD48FDE8FF5FFD91" author="Norell, M. A. & Clark, J. M. & Demberelyin, D. & Rhinchen, B. & Chiappe, L. M. & Davidson, A. R. & McKenna, M. C. & Altangerel, P. & Novacek, M. J." journalOrPublisher="Science" pageId="5" pageNumber="31" pagination="779 - 782" part="266" refId="ref7229" refString="Norell, M. A., Clark, J. M., Demberelyin, D., Rhinchen, B., Chiappe, L. M., Davidson, A. R., McKenna, M. C., Altangerel, P., Novacek, M. J., 1994. A theropod dinosaur embryo and the affinities of the Flaming Cliffs dinosaur eggs. Science 266, 779 - 782." title="A theropod dinosaur embryo and the affinities of the Flaming Cliffs dinosaur eggs" type="journal article" year="1994">Norell et al., 1994</bibRefCitation>
|
|
). Analysis of jaw mechanics in theropod dinosaurs clearly demonstrates the dissimilarity of oviraptosaurs and predatory theropods (
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FF3DFD5CFE4AFD58" author="Brusatte, S. L. & Sakamoto, M. & Montanari, S. & Harcourt Smith, W. E. H." box="[229,439,653,673]" journalOrPublisher="Journal of Evolutionary Biology" pageId="5" pageNumber="31" pagination="365 - 377" part="25" refId="ref5720" refString="Brusatte, S. L., Sakamoto, M., Montanari, S., Harcourt Smith, W. E. H., 2012 b. The evolution of cranial form and function in theropod dinosaurs: insights from geometric morphometrics. Journal of Evolutionary Biology 25, 365 - 377." title="The evolution of cranial form and function in theropod dinosaurs: insights from geometric morphometrics" type="journal article" year="2012">Brusatte et al., 2012b</bibRefCitation>
|
|
). The lack of the dentary groove is taken as further evidence that they may not have been active predators. The possibility that the common ancestor of Ornithomimosaurs, Oviraptorosaurs, and Therizinosaurs also lacked a dentary groove cannot be overlooked, especially given the absence of a groove in most other maniraptorans. While the presence of a beak does not necessarily indicate herbivorous lifestyle―as squid, placoderm fish and birds of prey all utilize beaks in predatory behavior―why a well-adapted predator like a theropod would evolve a beak to bolster a predatory lifestyle is unclear, and an interpretation of herbivory in this context is more parsimonious.
|
|
</paragraph>
|
|
<paragraph id="8BCACF21F05EFFA3FFA9FC09FDF3FC17" blockId="5.[113,526,987,1007]" box="[113,526,987,1007]" pageId="5" pageNumber="31">
|
|
<heading id="D082784DF05EFFA3FFA9FC09FDF3FC17" bold="true" box="[113,526,987,1007]" fontSize="8" level="2" pageId="5" pageNumber="31" reason="0">
|
|
<emphasis id="B9011333F05EFFA3FFA9FC09FDF3FC17" box="[113,526,987,1007]" italics="true" pageId="5" pageNumber="31">4.3. Absence of groove in tyrannosauroids</emphasis>
|
|
</heading>
|
|
</paragraph>
|
|
<paragraph id="8BCACF21F05EFFA3FF49FBC6FB8DFE3A" blockId="5.[113,784,1044,1984]" lastBlockId="5.[831,1501,179,1091]" pageId="5" pageNumber="31">
|
|
There are numerous tyrannosauroids that lacked the dentary groove. Assuming maximum parsimony for the distribution of the dentary groove, we must interpret several of these as independent losses. One potential explanation for the absence of the groove in certain taxa might be that the nerves and blood vessels accommodated by the groove occurred superficial to the dentary rather than along its surface. Another potential explanation for the loss of the groove in various tyrannosaurids is to enhance jaw strength. The groove could potentially serve as a point of weakness: forcemodeling experiments on the mandible of
|
|
<emphasis id="B9011333F05EFFA3FDE5FADCFD49FADA" box="[573,692,1294,1314]" italics="true" pageId="5" pageNumber="31">Erlikosaurus</emphasis>
|
|
demonstrate higher stress levels along the line of mandibular foramina during simulated bites (
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FE86FA95FD9EFAA2" author="Lautenschalger, S. & Witmer, L. M. & Altangerel, P. & Rayfield, E. J." box="[350,611,1351,1370]" pageId="5" pageNumber="31" pagination="20657 - 20662" part="110" refId="ref7069" refString="Lautenschalger, S., Witmer, L. M., Altangerel, P., Rayfield, E. J., 2013. Proceedings of the National Academy of Science 110, 20657 - 20662." title="Proceedings of the National Academy of Science" type="journal article" year="2013">Lautenschalger et al., 2013</bibRefCitation>
|
|
). The groove was likely eliminated as the cortical bone of the dentary was thickened to accommodate strong bite forces (
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FE3CFAADFD49FA6A" author="Therrien, F. & Henderson, D. M. & Ruff, C. B." box="[484,692,1407,1426]" editor="Carpenter, K." journalOrPublisher="Indiana University Press, Bloomington, Indiana" pageId="5" pageNumber="31" pagination="179 - 237" refId="ref7903" refString="Therrien, F., Henderson, D. M., Ruff, C. B., 2005. Bite me; Biomechanical models of theropod mandibles and implications for feeding behavior. In: Carpenter, K. (Ed.), The Carnivorous Dinosaurs. Indiana University Press, Bloomington, Indiana, pp. 179 - 237." title="Bite me; Biomechanical models of theropod mandibles and implications for feeding behavior" type="book chapter" volumeTitle="The Carnivorous Dinosaurs" year="2005">Therrien et al., 2005</bibRefCitation>
|
|
). Loss of the groove would therefore be advantageous from a mechanical perspective for the largest tyrannosaurids.
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FDE0FA64FCF2FA31" author="Snively, E. & Henderson, D. M. & Phillips, D. S." box="[568,783,1462,1482]" journalOrPublisher="Acta Palaeontologica Polonica" pageId="5" pageNumber="31" pagination="435 - 454" part="51" refId="ref7857" refString="Snively, E., Henderson, D. M., Phillips, D. S., 2006. Fused and vaulted nasals of tyrannosaurid dinosaurs: implications for cranial strength and feeding mechanics. Acta Palaeontologica Polonica 51, 435 - 454." title="Fused and vaulted nasals of tyrannosaurid dinosaurs: implications for cranial strength and feeding mechanics" type="journal article" year="2006">Snively et al. (2006)</bibRefCitation>
|
|
hypothesized that tyrannosaurines had stronger bite forces compared to albertosaurines and carnosaurs, due to vaulting of the skull, enhanced fusion of the cranial bones and skull kinematics. Tyrannosaurines likely consumed greater amounts of bone relative to smaller theropods (
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FEB9F990FE16F9AD" author="Fiorillo, A. R." box="[353,491,1602,1621]" journalOrPublisher="Palaeogeography, Palaeoclimatology & Palaeoecology" pageId="5" pageNumber="31" pagination="157 - 166" part="88" refId="ref6568" refString="Fiorillo, A. R., 1991. Prey utilization by predatory dinosaurs. Palaeogeography, Palaeoclimatology & Palaeoecology 88, 157 - 166." title="Prey utilization by predatory dinosaurs" type="journal article" year="1991">Fiorillo, 1991</bibRefCitation>
|
|
;
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FE23F990FCF6F9AD" author="Erickson, G. M. & Olson, K. H." box="[507,779,1602,1621]" journalOrPublisher="Journal of Vertebrate Paleontology" pageId="5" pageNumber="31" pagination="175 - 178" part="16" refId="ref6373" refString="Erickson, G. M., Olson, K. H., 1996. Bite marks attributable to Tyrannosaurus rex: preliminary description and implications. Journal of Vertebrate Paleontology 16, 175 - 178." title="Bite marks attributable to Tyrannosaurus rex: preliminary description and implications" type="journal article" year="1996">Erickson and Olson, 1996</bibRefCitation>
|
|
;
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FFA9F98CFECFF989" author="Snively, E. & Henderson, D. M. & Phillips, D. S." box="[113,306,1630,1649]" journalOrPublisher="Acta Palaeontologica Polonica" pageId="5" pageNumber="31" pagination="435 - 454" part="51" refId="ref7857" refString="Snively, E., Henderson, D. M., Phillips, D. S., 2006. Fused and vaulted nasals of tyrannosaurid dinosaurs: implications for cranial strength and feeding mechanics. Acta Palaeontologica Polonica 51, 435 - 454." title="Fused and vaulted nasals of tyrannosaurid dinosaurs: implications for cranial strength and feeding mechanics" type="journal article" year="2006">Snively et al., 2006</bibRefCitation>
|
|
). That makes sense, given that (1) observation of modern ecosystems demonstrates that predators with stronger bite forces tend to consume more portions of the prey (
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FD30F944FED3F93C" author="Van Valkenburgh, B." journalOrPublisher="Journal of Mammalogy" pageId="5" pageNumber="31" pagination="240 - 254" part="1" refId="ref8013" refString="Van Valkenburgh, B., 1996. Feeding behavior in free-ranging, large African carnivores. Journal of Mammalogy 1, 240 - 254." title="Feeding behavior in free-ranging, large African carnivores" type="journal article" year="1996">Van Valkenburgh, 1996</bibRefCitation>
|
|
) and (2) the presence of prey items (e.g., ceratopsians) in the Cretaceous which possess bony frills. Large tyrannosaurids used a “puncture and pull” feeding strategy (
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FD1EF93BFF5BF8E0" author="Bakker, R. T." bookContentInfo="481 pp." journalOrPublisher="William and Morrow, New York, New York" pageId="5" pageNumber="31" refId="ref5468" refString="Bakker, R. T., 1986. The Dinosaur Heresies. William and Morrow, New York, New York, 481 pp." title="The Dinosaur Heresies" type="book" year="1986">Bakker, 1986</bibRefCitation>
|
|
;
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FF6AF8D7FE4EF8E0" author="Molnar, R. E. & Farlow, J. O." box="[178,435,1797,1816]" editor="Weishampel, D. B. & Dodson, P. & Osmolska, H." journalOrPublisher="University of California Press, Los Angeles, California" pageId="5" pageNumber="31" pagination="210 - 224" refId="ref7168" refString="Molnar, R. E., Farlow, J. O., 1990. Carnosaur paleobiology. In: Weishampel, D. B., Dodson, P., Osmolska, H. (Eds.), The Dinosauria. University of California Press, Los Angeles, California, pp. 210 - 224." title="Carnosaur paleobiology" type="book chapter" volumeTitle="The Dinosauria" year="1990">Molnar and Farlow, 1990</bibRefCitation>
|
|
;
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FE67F8D7FD3DF8E0" author="Erickson, G. M. & Olson, K. H." box="[447,704,1797,1816]" journalOrPublisher="Journal of Vertebrate Paleontology" pageId="5" pageNumber="31" pagination="175 - 178" part="16" refId="ref6373" refString="Erickson, G. M., Olson, K. H., 1996. Bite marks attributable to Tyrannosaurus rex: preliminary description and implications. Journal of Vertebrate Paleontology 16, 175 - 178." title="Bite marks attributable to Tyrannosaurus rex: preliminary description and implications" type="journal article" year="1996">Erickson and Olson, 1996</bibRefCitation>
|
|
) which required that the teeth penetrate bone, in order to effectively anchor the jaws into the prey. This feeding behavior has been interpreted from bite marks on ceratopsians (
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FDD0F88BFCFFF894" author="Erickson, G. M. & Olson, K. H." box="[520,770,1881,1900]" journalOrPublisher="Journal of Vertebrate Paleontology" pageId="5" pageNumber="31" pagination="175 - 178" part="16" refId="ref6373" refString="Erickson, G. M., Olson, K. H., 1996. Bite marks attributable to Tyrannosaurus rex: preliminary description and implications. Journal of Vertebrate Paleontology 16, 175 - 178." title="Bite marks attributable to Tyrannosaurus rex: preliminary description and implications" type="journal article" year="1996">Erickson and Olson, 1996</bibRefCitation>
|
|
). Other theropods (e.g,
|
|
<emphasis id="B9011333F05EFFA3FE94F8A6FDAFF870" box="[332,594,1908,1928]" italics="true" pageId="5" pageNumber="31">
|
|
<taxonomicName id="4C75B4A2F05EFFA3FE94F8A6FE4FF870" authorityName="Marsh" authorityYear="1877" box="[332,434,1908,1928]" class="Reptilia" family="Allosauridae" genus="Allosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="31" phylum="Chordata" rank="genus">Allosaurus</taxonomicName>
|
|
,
|
|
<taxonomicName id="4C75B4A2F05EFFA3FE63F8A6FDAFF870" authorityName="Coria & Salgado" authorityYear="1995" box="[443,594,1908,1928]" class="Reptilia" family="Carcharodontosauridae" genus="Giganotosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="31" phylum="Chordata" rank="genus">Giganotosaurus</taxonomicName>
|
|
</emphasis>
|
|
) may have instead relied on cranial kinesis and thin, slicing teeth to wound their prey (
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FFA1F87FFF18F838" author="Paul, G. S." bookContentInfo="464 pp." box="[121,229,1965,1984]" journalOrPublisher="Simon and Schuster, New York, New York" pageId="5" pageNumber="31" refId="ref7501" refString="Paul, G. S., 1988. Predatory Dinosaurs of the World: A Complete Illustrated Guide. Simon and Schuster, New York, New York, 464 pp." title="Predatory Dinosaurs of the World: A Complete Illustrated Guide" type="book" year="1988">Paul, 1988</bibRefCitation>
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;
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<bibRefCitation id="EFE4B2D0F05EFFA3FF28F87FFE43F838" author="Rayfield, E. J. & Norman, D. B. & Horner, C. C. & Horner, J. R. & Smith, P. M. & Thomason, J. J. & Upchurch, P." box="[240,446,1964,1984]" journalOrPublisher="Nature" pageId="5" pageNumber="31" pagination="1033 - 1037" part="409" refId="ref7674" refString="Rayfield, E. J., Norman, D. B., Horner, C. C., Horner, J. R., Smith, P. M., Thomason, J. J., Upchurch, P., 2001. Cranial design and function in a large theropod dinosaur. Nature 409, 1033 - 1037." title="Cranial design and function in a large theropod dinosaur" type="journal article" year="2001">Rayfield et al., 2001</bibRefCitation>
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;
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<bibRefCitation id="EFE4B2D0F05EFFA3FE12F87FFD68F838" author="Therrien, F. & Henderson, D. M. & Ruff, C. B." box="[458,661,1965,1984]" editor="Carpenter, K." journalOrPublisher="Indiana University Press, Bloomington, Indiana" pageId="5" pageNumber="31" pagination="179 - 237" refId="ref7903" refString="Therrien, F., Henderson, D. M., Ruff, C. B., 2005. Bite me; Biomechanical models of theropod mandibles and implications for feeding behavior. In: Carpenter, K. (Ed.), The Carnivorous Dinosaurs. Indiana University Press, Bloomington, Indiana, pp. 179 - 237." title="Bite me; Biomechanical models of theropod mandibles and implications for feeding behavior" type="book chapter" volumeTitle="The Carnivorous Dinosaurs" year="2005">Therrien et al. 2005</bibRefCitation>
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), instead of ripping large portions (e.g., limbs) from the body of the prey. Since the groove conducted a nerve along the surface of the dentary, a powerful bite may also have been intrinsically painful. The nerve may have been reduced and the groove therefore eliminated, as more powerful biting force evolved in tyrannosaurids. A biomechanical explanation for the loss of the groove is appealing, because large carcharodontosaurids were stratigraphically contemporaneous with tyrannosaurines and, in some cases, were larger than tyrannosaurines. Thus increase in size alone is not sufficient to explain the loss of the groove.
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</paragraph>
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<paragraph id="8BCACF21F05EFFA3FC87FE18FBDBFC78" blockId="5.[831,1501,179,1091]" pageId="5" pageNumber="31">
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The variable distribution of the groove among tyrannosaurids may explain the seemingly incompatible cohabitation (
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<bibRefCitation id="EFE4B2D0F05EFFA3FAB5FE34FC3DFDED" author="Farlow, J. O. & Pianka, E. R." journalOrPublisher="Historical Biology" pageId="5" pageNumber="31" pagination="21 - 40" part="16" refId="ref6520" refString="Farlow, J. O., Pianka, E. R., 2003. Body size overlap, habitat partitioning and living space requirements of terrestrial vertebrate predators: implications for the paleoecology of large theropod dinosaurs. Historical Biology 16, 21 - 40." title="Body size overlap, habitat partitioning and living space requirements of terrestrial vertebrate predators: implications for the paleoecology of large theropod dinosaurs" type="journal article" year="2003">Farlow and Pianka, 2003</bibRefCitation>
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) of
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<taxonomicName id="4C75B4A2F05EFFA3FC31FDD3FB81FDED" authorityName="Russell" authorityYear="1970" box="[1001,1148,513,533]" class="Reptilia" family="Tyrannosauridae" genus="Daspletosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="31" phylum="Chordata" rank="genus">
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<emphasis id="B9011333F05EFFA3FC31FDD3FB81FDED" box="[1001,1148,513,533]" italics="true" pageId="5" pageNumber="31">Daspletosaurus</emphasis>
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</taxonomicName>
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(in which a groove is absent) with
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<taxonomicName id="4C75B4A2F05EFFA3FCE7FDCFFC44FDC9" baseAuthorityName="Gilmore" baseAuthorityYear="1946" box="[831,953,541,561]" class="Reptilia" family="Tyrannosauridae" genus="Gorgosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="31" phylum="Chordata" rank="genus">
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<emphasis id="B9011333F05EFFA3FCE7FDCFFC44FDC9" box="[831,953,541,561]" italics="true" pageId="5" pageNumber="31">Gorgosaurus</emphasis>
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</taxonomicName>
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and
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<taxonomicName id="4C75B4A2F05EFFA3FC2AFDCFFB8AFDC9" authorityName="Osborn" authorityYear="1905" box="[1010,1143,541,561]" class="Reptilia" family="Tyrannosauridae" genus="Albertosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="31" phylum="Chordata" rank="genus">
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<emphasis id="B9011333F05EFFA3FC2AFDCFFB8AFDC9" box="[1010,1143,541,561]" italics="true" pageId="5" pageNumber="31">Albertosaurus</emphasis>
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</taxonomicName>
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(in which the groove is present).
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<taxonomicName id="4C75B4A2F05EFFA3FCE7FDEBFC2FFDB5" authorityName="Russell" authorityYear="1970" box="[831,978,569,589]" class="Reptilia" family="Tyrannosauridae" genus="Daspletosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="31" phylum="Chordata" rank="genus">
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<emphasis id="B9011333F05EFFA3FCE7FDEBFC2FFDB5" box="[831,978,569,589]" italics="true" pageId="5" pageNumber="31">Daspletosaurus</emphasis>
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</taxonomicName>
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may have been adapted to eating prey that required powerful bites to subdue or consume, whereas the albertosaurines were more lightly built predators that perhaps preferred less robust prey. This is in keeping with
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<bibRefCitation id="EFE4B2D0F05EFFA3FB52FD5FFAD0FD59" author="Russell, D. A." box="[1162,1325,653,673]" journalOrPublisher="National Museum of Natural Science Publications in Palaeontology" pageId="5" pageNumber="31" pagination="1 - 34" part="1" refId="ref7740" refString="Russell, D. A., 1970. Tyrannosaurs from the Late Cretaceous of western Canada. National Museum of Natural Science Publications in Palaeontology 1, 1 - 34." title="Tyrannosaurs from the Late Cretaceous of western Canada" type="journal article" year="1970">Russell's (1970)</bibRefCitation>
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hypothesis that albertosaurines preyed on hadrosaurs, whereas
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<taxonomicName id="4C75B4A2F05EFFA3FA91FD7AFA21FD44" authorityName="Russell" authorityYear="1970" box="[1353,1500,680,700]" class="Reptilia" family="Tyrannosauridae" genus="Daspletosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="31" phylum="Chordata" rank="genus">
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<emphasis id="B9011333F05EFFA3FA91FD7AFA21FD44" box="[1353,1500,680,700]" italics="true" pageId="5" pageNumber="31">Daspletosaurus</emphasis>
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</taxonomicName>
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specialized on ceratopsians. Tyrannosaurines are known to have taken hadrosaurs as prey items (
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<bibRefCitation id="EFE4B2D0F05EFFA3FB57FD33FAC4FD0C" author="Varricchio, D. J." box="[1167,1337,737,756]" journalOrPublisher="Journal of Paleontology" pageId="5" pageNumber="31" pagination="401 - 406" part="75" refId="ref8039" refString="Varricchio, D. J., 2001. Gut contents from a Cretaceous tyrannosaurid: implications for theropod dinosaur digestive tracts. Journal of Paleontology 75, 401 - 406." title="Gut contents from a Cretaceous tyrannosaurid: implications for theropod dinosaur digestive tracts" type="journal article" year="2001">Varricchio, 2001</bibRefCitation>
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;
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<bibRefCitation id="EFE4B2D0F05EFFA3FA9DFD33FC92FCE8" author="DePalma, R. A. & Burnham, D. A. & Martin, L. D. & Rothschild, B. M. & Larson, P. L." journalOrPublisher="Proceedings of the National Academy of Science" pageId="5" pageNumber="31" pagination="12560 - 12564" part="110" refId="ref6268" refString="DePalma, R. A., Burnham, D. A., Martin, L. D., Rothschild, B. M., Larson, P. L., 2013. Physical evidence of predatory behavior in Tyrannosaurus rex. Proceedings of the National Academy of Science 110, 12560 - 12564." title="Physical evidence of predatory behavior in Tyrannosaurus rex" type="journal article" year="2013">DePalma et al., 2013</bibRefCitation>
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). Rather than invalidate our hypothesis, this merely is evidence that tyrannosaurines were large, powerfully built predators that were capable of taking any suitable prey items in their environment. This explanation is consistent with the mechanical hypothesis we pose here.
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</paragraph>
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<paragraph id="8BCACF21F05EFFA3FC87FC5BFB88FBBB" blockId="5.[831,1501,179,1091]" pageId="5" pageNumber="31">
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A potential flaw in this hypothesis is the absence of the groove in many smaller tyrannosauroid genera, such as
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<emphasis id="B9011333F05EFFA3FADBFC71FA98FC4F" box="[1283,1381,931,951]" italics="true" pageId="5" pageNumber="31">Alioramus</emphasis>
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,
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<emphasis id="B9011333F05EFFA3FAB6FC71FA50FC4F" box="[1390,1453,931,951]" italics="true" pageId="5" pageNumber="31">Dilong</emphasis>
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, and
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<emphasis id="B9011333F05EFFA3FCE7FC6DFC51FC2B" box="[831,940,959,979]" italics="true" pageId="5" pageNumber="31">Eotyrannus</emphasis>
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. While an examination of the bite force of these taxa is beyond the scope of the present study, it may be the case that these smaller tyrannosauroids were also exerting relatively high bite forces on their prey or otherwise needed to strengthen their jaws for successful food acquisition.
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</paragraph>
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<paragraph id="8BCACF21F05EFFA3FCE7FBB4FC35FB6E" blockId="5.[831,1391,1126,1174]" pageId="5" pageNumber="31">
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<heading id="D082784DF05EFFA3FCE7FBB4FC35FB6E" bold="true" fontSize="8" level="2" pageId="5" pageNumber="31" reason="0">
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<emphasis id="B9011333F05EFFA3FCE7FBB4FB8FFB82" box="[831,1138,1126,1146]" italics="true" pageId="5" pageNumber="31">4.4. Interpreting the identity of</emphasis>
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“
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<emphasis id="B9011333F05EFFA3FB5AFBB4FB56FB82" box="[1154,1195,1126,1146]" italics="true" pageId="5" pageNumber="31">Jane</emphasis>
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”
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<emphasis id="B9011333F05EFFA3FB64FBB4FC35FB6E" italics="true" pageId="5" pageNumber="31">
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and the validity of
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<taxonomicName id="4C75B4A2F05EFFA3FCE7FB50FC35FB6E" authority="Bakker et al., 1988" authorityName="Bakker et al." authorityYear="1988" box="[831,968,1154,1174]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="31" phylum="Chordata" rank="genus">Nanotyrannus</taxonomicName>
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</emphasis>
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</heading>
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</paragraph>
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<paragraph id="8BCACF21F05EFFA3FC87FB69FBD9FA1D" blockId="5.[831,1501,1211,1984]" pageId="5" pageNumber="31">
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The mosaic distribution of the dentary groove within Tyrannosauroidea allows an opportunity to use the occurrence of this character to determine the relationship of the embattled
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<taxonomicName id="4C75B4A2F05EFFA3FA78FB20FC68FADA" authority="Bakker et al., 1988" authorityName="Bakker et al." authorityYear="1988" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="31" phylum="Chordata" rank="genus">
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<emphasis id="B9011333F05EFFA3FA78FB20FC68FADA" italics="true" pageId="5" pageNumber="31">Nanotyrannus</emphasis>
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</taxonomicName>
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|
to other tyrannosaurs.
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<taxonomicName id="4C75B4A2F05EFFA3FBA3FADCFAD0FADA" authorityName="Osborn" authorityYear="1905" box="[1147,1325,1294,1314]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="33" phylum="Chordata" rank="species" species="rex">
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<emphasis id="B9011333F05EFFA3FBA3FADCFAD0FADA" box="[1147,1325,1294,1314]" italics="true" pageId="5" pageNumber="31">Tyrannosaurus rex</emphasis>
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</taxonomicName>
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|
lacks this groove, whereas it is a distinct character in “Jane” and the other
|
|
<taxonomicName id="4C75B4A2F05EFFA3FA78FAF8FC08FAA2" baseAuthorityName="Gilmore" baseAuthorityYear="1946" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="31" phylum="Chordata" rank="species" species="lancensis">
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|
<emphasis id="B9011333F05EFFA3FA78FAF8FC08FAA2" italics="true" pageId="5" pageNumber="31">Nanotyrannus lancensis</emphasis>
|
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</taxonomicName>
|
|
specimens in which the dentary is visible. The occurrence of the dentary groove in
|
|
<taxonomicName id="4C75B4A2F05EFFA3FB73FAB3FAE0FA8D" baseAuthorityName="Gilmore" baseAuthorityYear="1946" box="[1195,1309,1377,1397]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="31" phylum="Chordata" rank="species" species="lancensis">
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|
<emphasis id="B9011333F05EFFA3FB73FAB3FAE0FA8D" box="[1195,1309,1377,1397]" italics="true" pageId="5" pageNumber="31">N. lancensis</emphasis>
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|
</taxonomicName>
|
|
, but not in
|
|
<taxonomicName id="4C75B4A2F05EFFA3FA57FAB3FA3CFA8D" authorityName="Osborn" authorityYear="1905" box="[1423,1473,1377,1397]" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="33" phylum="Chordata" rank="species" species="rex">
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<emphasis id="B9011333F05EFFA3FA57FAB3FA3CFA8D" box="[1423,1473,1377,1397]" italics="true" pageId="5" pageNumber="31">T. rex</emphasis>
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|
</taxonomicName>
|
|
, is itself independent evidence of separation of these two taxa. The presence of the groove stands with more than 30 other skeletal characters as evidence to separate
|
|
<taxonomicName id="4C75B4A2F05EFFA3FB6CFA67FAC0FA31" authority="Bakker et al., 1988" authorityName="Bakker et al." authorityYear="1988" box="[1204,1341,1461,1481]" class="Reptilia" family="Tyrannosauridae" genus="Nanotyrannus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="31" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05EFFA3FB6CFA67FAC0FA31" box="[1204,1341,1461,1481]" italics="true" pageId="5" pageNumber="31">Nanotyrannus</emphasis>
|
|
</taxonomicName>
|
|
from
|
|
<taxonomicName id="4C75B4A2F05EFFA3FA5BFA67FBDDFA1D" authorityName="Osborn" authorityYear="1905" class="Reptilia" family="Tyrannosauridae" genus="Tyrannosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Dinosauria" pageId="5" pageNumber="31" phylum="Chordata" rank="genus">
|
|
<emphasis id="B9011333F05EFFA3FA5BFA67FC82FA1D" italics="true" pageId="5" pageNumber="31">Tyrannosaurus</emphasis>
|
|
(
|
|
<bibRefCitation id="EFE4B2D0F05EFFA3FC55FA01FBEBFA1E" author="Larson, P." box="[909,1046,1491,1510]" editor="Parrish, J. M. & Molnar, R. E. & Currie, P. J. & Koppelhus, E. B." journalOrPublisher="Indiana University Press, Bloomington, Indiana" pageId="5" pageNumber="31" pagination="14 - 53" refId="ref6938" refString="Larson, P., 2013 a. The case for Nanotyrannus. In: Parrish, J. M., Molnar, R. E., Currie, P. J., Koppelhus, E. B. (Eds.), Tyrannosaurid Paleobiology. Indiana University Press, Bloomington, Indiana, pp. 14 - 53." title="The case for Nanotyrannus" type="book chapter" volumeTitle="Tyrannosaurid Paleobiology" year="2013">Larson, 2013a</bibRefCitation>
|
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)
|
|
</taxonomicName>
|
|
.
|
|
</paragraph>
|
|
</subSubSection>
|
|
</treatment>
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</document> |