546 lines
96 KiB
XML
546 lines
96 KiB
XML
<document ID-DOI="http://doi.org/10.5281/zenodo.5842015" ID-GBIF-Dataset="4971b307-67fe-49a2-8401-a744db5f4c58" ID-GBIF-Taxon="192044143" ID-Zenodo-Dep="5842015" approvalRequired="14" approvalRequired_for_bibRefs="12" approvalRequired_for_document="1" approvalRequired_for_taxonomicNames="1" checkinTime="1642012861139" checkinUser="felipe" docAuthor="Maidment, Susannah C. R., Strachan, Sarah J., Ouarhache, Driss, Scheyer, Torsten M., Brown, Emily E., Fernandez, Vincent, Johanson, Zerina, Raven, Thomas J. & Barrett, Paul M." docDate="2021" docId="03E0004D1F78FFE8D66EF9E1FD9DFAF3" docLanguage="en" docName="NatureEcolEvol.5.1576-1581.pdf.imf" docOrigin="Nature Ecology & Evolution 5 (12)" docSource="http://dx.doi.org/10.1038/s41559-021-01553-6" docTitle="Spicomellus afer Maidment & Strachan & Ouarhache & Scheyer & Brown & Fernandez & Johanson & Raven & Barrett 2021, gen. et sp. nov." docType="treatment" docVersion="6" lastPageId="3" lastPageNumber="1576" masterDocId="FFD978351F78FFEBD61FFFA4FFBAFFD4" masterDocTitle="Bizarre dermal armour suggests the first African ankylosaur" masterLastPageNumber="1581" masterPageNumber="1576" pageId="0" pageNumber="1576" updateTime="1643428674033" updateUser="ExternalLinkService">
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<mods:mods xmlns:mods="http://www.loc.gov/mods/v3">
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<mods:titleInfo>
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<mods:title>Bizarre dermal armour suggests the first African ankylosaur</mods:title>
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</mods:titleInfo>
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<mods:name type="personal">
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<mods:role>
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<mods:roleTerm>Author</mods:roleTerm>
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</mods:role>
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<mods:namePart>Maidment, Susannah C. R.</mods:namePart>
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<mods:nameIdentifier type="ORCID">0000-0002-7741-2500</mods:nameIdentifier>
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<mods:affiliation>Department of Earth Sciences, Natural History Museum, London, UK & School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK</mods:affiliation>
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<mods:nameIdentifier type="email">susannah.maidment@nhm.ac.uk</mods:nameIdentifier>
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</mods:name>
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<mods:name type="personal">
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<mods:role>
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<mods:roleTerm>Author</mods:roleTerm>
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</mods:role>
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<mods:namePart>Strachan, Sarah J.</mods:namePart>
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<mods:affiliation>Department of Earth Sciences, University College London, London, UK</mods:affiliation>
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</mods:name>
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<mods:name type="personal">
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<mods:role>
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<mods:roleTerm>Author</mods:roleTerm>
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</mods:role>
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<mods:namePart>Ouarhache, Driss</mods:namePart>
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<mods:affiliation>GERA Laboratory, Faculty of Sciences Dhar El Mahraz, SMBA University, Fez, Morocco</mods:affiliation>
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</mods:name>
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<mods:name type="personal">
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<mods:role>
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<mods:roleTerm>Author</mods:roleTerm>
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</mods:role>
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<mods:namePart>Scheyer, Torsten M.</mods:namePart>
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<mods:nameIdentifier type="ORCID">0000-0002-6301-8983</mods:nameIdentifier>
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<mods:affiliation>Palaeontological Institute and Museum, University of Zurich, Zurich, Switzerland</mods:affiliation>
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</mods:name>
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<mods:name type="personal">
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<mods:role>
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<mods:roleTerm>Author</mods:roleTerm>
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</mods:role>
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<mods:namePart>Brown, Emily E.</mods:namePart>
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<mods:affiliation>Department of Earth Sciences, Natural History Museum, London, UK & School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK</mods:affiliation>
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</mods:name>
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<mods:name type="personal">
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<mods:role>
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<mods:roleTerm>Author</mods:roleTerm>
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</mods:role>
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<mods:namePart>Fernandez, Vincent</mods:namePart>
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<mods:affiliation>Department of Earth Sciences, Natural History Museum, London, UK</mods:affiliation>
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</mods:name>
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<mods:name type="personal">
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<mods:role>
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<mods:roleTerm>Author</mods:roleTerm>
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</mods:role>
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<mods:namePart>Johanson, Zerina</mods:namePart>
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<mods:affiliation>Department of Earth Sciences, Natural History Museum, London, UK</mods:affiliation>
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</mods:name>
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<mods:name type="personal">
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<mods:role>
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<mods:roleTerm>Author</mods:roleTerm>
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</mods:role>
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<mods:namePart>Raven, Thomas J.</mods:namePart>
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<mods:affiliation>Department of Earth Sciences, Natural History Museum, London, UK & School of Environment and Technology, University of Brighton, Brighton, UK</mods:affiliation>
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</mods:name>
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<mods:name type="personal">
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<mods:role>
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<mods:roleTerm>Author</mods:roleTerm>
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</mods:role>
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<mods:namePart>Barrett, Paul M.</mods:namePart>
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<mods:nameIdentifier type="ORCID">0000-0003-0412-3000</mods:nameIdentifier>
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<mods:affiliation>Department of Earth Sciences, Natural History Museum, London, UK & Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa</mods:affiliation>
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</mods:name>
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<mods:typeOfResource>text</mods:typeOfResource>
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<mods:title>Nature Ecology & Evolution</mods:title>
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</mods:titleInfo>
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<mods:part>
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<mods:date>2021</mods:date>
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<mods:detail type="pubDate">
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<mods:number>2021-09-23</mods:number>
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</mods:detail>
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<mods:detail type="volume">
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<mods:number>5</mods:number>
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</mods:detail>
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<mods:detail type="issue">
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<mods:number>12</mods:number>
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</mods:detail>
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<mods:extent unit="page">
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<mods:start>1576</mods:start>
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<mods:end>1581</mods:end>
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</mods:extent>
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</mods:part>
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</mods:relatedItem>
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<mods:location>
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<mods:url>http://dx.doi.org/10.1038/s41559-021-01553-6</mods:url>
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</mods:location>
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<mods:classification>journal article</mods:classification>
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<mods:identifier type="DOI">10.1038/s41559-021-01553-6</mods:identifier>
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<mods:identifier type="GBIF-Dataset">4971b307-67fe-49a2-8401-a744db5f4c58</mods:identifier>
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<mods:identifier type="Zenodo-Dep">5842122</mods:identifier>
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</mods:mods>
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<treatment ID-DOI="http://doi.org/10.5281/zenodo.5842015" ID-GBIF-Taxon="192044143" ID-Zenodo-Dep="5842015" LSID="urn:lsid:plazi:treatment:03E0004D1F78FFE8D66EF9E1FD9DFAF3" httpUri="http://treatment.plazi.org/id/03E0004D1F78FFE8D66EF9E1FD9DFAF3" lastPageId="3" lastPageNumber="1576" pageId="0" pageNumber="1576">
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<subSubSection box="[113,429,1605,1628]" pageId="0" pageNumber="1576" type="nomenclature">
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<paragraph blockId="0.[113,777,1491,1684]" box="[113,429,1605,1628]" pageId="0" pageNumber="1576">
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<taxonomicName authority="Maidment & Strachan & Ouarhache & Scheyer & Brown & Fernandez & Johanson & Raven & Barrett, 2021" authorityName="Maidment & Strachan & Ouarhache & Scheyer & Brown & Fernandez & Johanson & Raven & Barrett" authorityYear="2021" box="[113,279,1605,1628]" genus="Spicomellus" kingdom="Animalia" order="Ornithischia" pageId="0" pageNumber="1576" rank="species" species="afer" status="gen. et sp. nov.">
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<emphasis bold="true" box="[113,279,1605,1628]" italics="true" pageId="0" pageNumber="1576">Spicomellus afer</emphasis>
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</taxonomicName>
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<taxonomicNameLabel box="[284,429,1606,1627]" pageId="0" pageNumber="1576" rank="species">gen. et sp. nov.</taxonomicNameLabel>
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</paragraph>
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</subSubSection>
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||
<subSubSection pageId="0" pageNumber="1576" type="description">
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||
<paragraph blockId="0.[113,777,1491,1684]" pageId="0" pageNumber="1576">
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LSID: urn:lsid:zoobank.org:act:D
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<docIssue box="[440,463,1634,1656]" pageId="0" pageNumber="1576">12</docIssue>
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||
DDAB4-E164-411D-8406-B7B 3DEC52F71
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||
</paragraph>
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||
</subSubSection>
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||
<subSubSection pageId="0" pageNumber="1576" type="etymology">
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<paragraph blockId="0.[113,777,1718,1796]" pageId="0" pageNumber="1576">
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||
<emphasis bold="true" box="[113,230,1718,1739]" pageId="0" pageNumber="1576">Etymology.</emphasis>
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<emphasis box="[242,303,1718,1739]" italics="true" pageId="0" pageNumber="1576">Spicus</emphasis>
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meaning spike (Latin);
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<emphasis box="[563,625,1718,1739]" italics="true" pageId="0" pageNumber="1576">mellus</emphasis>
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, a collar with spikes (Latin). A reference to the morphology of the specimen.
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<emphasis box="[736,777,1746,1767]" italics="true" pageId="0" pageNumber="1576">Afer</emphasis>
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(Latin), an inhabitant of Africa.
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</paragraph>
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</subSubSection>
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<subSubSection pageId="0" pageNumber="1576" type="materials_examined">
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<paragraph blockId="0.[810,1474,878,956]" lastBlockId="0.[810,1475,990,1152]" pageId="0" pageNumber="1576">
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<materialsCitation ID-GBIF-Occurrence="3435902301" collectionCode="NHMUK" country="Morocco" location="El Mers III Formation (Upper Bathonian / Callovian, Middle Jurassic: 168.3 - 163.5 million years ago), Boulahfa" municipality="Boulemane" pageId="0" pageNumber="1576" specimenCode="NHMUK PV R37412" specimenCount="1" stateProvince="Fez-Meknes" typeStatus="holotype">
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<emphasis bold="true" box="[810,912,878,899]" pageId="0" pageNumber="1576">
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<typeStatus box="[810,908,878,899]" pageId="0" pageNumber="1576">Holotype</typeStatus>
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.
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</emphasis>
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<specimenCode box="[915,1122,878,899]" pageId="0" pageNumber="1576">NHMUK PV R37412</specimenCode>
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, a partial rib bearing four co-ossified spines (
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<figureCitation box="[885,978,906,928]" captionStart="Fig" captionStartId="1.[113,143,1216,1236]" captionTargetBox="[263,1349,141,1183]" captionTargetId="figure-377@1.[299,1295,598,1183]" captionTargetPageId="1" captionText="Fig. 1 | Morphology and histology of Spicomellus afer, NHMUK PV R37412. a–d, Photographs (a,b) and 3D model produced from XCT scanning (c,d) showing the specimen in anterior/posterior (a,c) and dorsal (b,d) views. Red lines on a and b indicate where the specimen was sectioned for histological analysis. Red colouration on c and d indicates a cement used to consolidate the specimen. e–g, Thin-section photographs of the rod: full section of the rod (e) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (f) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (g) showing heavily remodelled cortical bone. Yellow box in e indicates the position of f, blue box indicates the position of g. h, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in Spicomellus (f). i, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of Spicomellus (g)." figureDoi="http://doi.org/10.5281/zenodo.5842124" httpUri="https://zenodo.org/record/5842124/files/figure.png" pageId="0" pageNumber="1576">Fig. 1a–d</figureCitation>
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) housed at the Natural History Museum, London (
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<collectionCode box="[817,918,934,956]" collectionName="NHMUK" pageId="0" pageNumber="1576">NHMUK</collectionCode>
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).
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<emphasis bold="true" box="[810,1034,990,1012]" pageId="0" pageNumber="1576">Horizon and locality.</emphasis>
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<location LSID="urn:lsid:plazi:treatment:03E0004D1F78FFE8D66EF9E1FD9DFAF3:8E96E7801F78FFEBD20BFC7AFA05FBC4" country="Morocco" municipality="Boulemane" name="El Mers III Formation (Upper Bathonian / Callovian, Middle Jurassic: 168.3 - 163.5 million years ago), Boulahfa" pageId="0" pageNumber="1576" stateProvince="Fez-Meknes">El Mers III Formation (Upper Bathonian/ Callovian, Middle Jurassic: 168.3–163.5 million years ago), Boulahfa</location>
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, south of
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<collectingMunicipality box="[898,1011,1046,1068]" pageId="0" pageNumber="1576">Boulemane</collectingMunicipality>
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,
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<collectingRegion box="[1021,1141,1046,1068]" pageId="0" pageNumber="1576">Fez-Meknes</collectingRegion>
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,
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<collectingCountry box="[1152,1240,1046,1067]" name="Morocco" pageId="0" pageNumber="1576">Morocco</collectingCountry>
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(detailed locality information can be found in ref.
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<bibRefCitation author="Maidment, S. C. R. & Raven, T. J. & Ouarhache, D. & Barrett, P. M." box="[1079,1086,1073,1085]" journalOrPublisher="Gondwana Res." pageId="0" pageNumber="1576" pagination="82 - 97" part="77" refId="ref4800" refString="4. Maidment, S. C. R., Raven, T. J., Ouarhache, D. & Barrett, P. M. North Africa's first stegosaur: implications for Gondwanan thyreophoran dinosaur diversity. Gondwana Res. 77, 82 - 97 (2020)." title="North Africa's first stegosaur: implications for Gondwanan thyreophoran dinosaur diversity" type="journal article" year="2020">
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||
<superScript attach="right" box="[1079,1086,1073,1085]" fontSize="5" pageId="0" pageNumber="1576">4</superScript>
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</bibRefCitation>
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||
). Maidment et al.
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<bibRefCitation author="Maidment, S. C. R. & Raven, T. J. & Ouarhache, D. & Barrett, P. M." box="[1259,1266,1073,1085]" journalOrPublisher="Gondwana Res." pageId="0" pageNumber="1576" pagination="82 - 97" part="77" refId="ref4800" refString="4. Maidment, S. C. R., Raven, T. J., Ouarhache, D. & Barrett, P. M. North Africa's first stegosaur: implications for Gondwanan thyreophoran dinosaur diversity. Gondwana Res. 77, 82 - 97 (2020)." title="North Africa's first stegosaur: implications for Gondwanan thyreophoran dinosaur diversity" type="journal article" year="2020">
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<superScript attach="left" box="[1259,1266,1073,1085]" fontSize="5" pageId="0" pageNumber="1576">4</superScript>
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</bibRefCitation>
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reported the horizon as lying in the El Mers II Formation, but subsequent field observations at the site suggest that it may lie slightly higher in the stratigraphy.
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</materialsCitation>
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</paragraph>
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||
</subSubSection>
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<subSubSection pageId="0" pageNumber="1576" type="diagnosis">
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<paragraph blockId="0.[810,1474,1186,1292]" pageId="0" pageNumber="1576">
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<emphasis bold="true" box="[810,919,1186,1208]" pageId="0" pageNumber="1576">Diagnosis.</emphasis>
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Differs from all other armoured dinosaurs in possessing ‘T’-shaped dorsal ribs with a fused, rod-like osteoderm on the dorsal surface, from which projects a series of co-ossified conical dermal spines.
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</paragraph>
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</subSubSection>
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<subSubSection lastPageId="3" pageId="0" pageNumber="1576" type="description">
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<paragraph blockId="0.[810,1475,1326,1796]" pageId="0" pageNumber="1576">
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<emphasis bold="true" box="[810,1068,1326,1348]" pageId="0" pageNumber="1576">Osteological description.</emphasis>
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NHMUK PV R37412 is a slightly curved dorsal rib fragment fused to a flat plate-like osteoderm and bearing four elongate, conical spines that project from its dorsal surface (
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<figureCitation box="[861,955,1410,1432]" captionStart="Fig" captionStartId="1.[113,143,1216,1236]" captionTargetBox="[263,1349,141,1183]" captionTargetId="figure-377@1.[299,1295,598,1183]" captionTargetPageId="1" captionText="Fig. 1 | Morphology and histology of Spicomellus afer, NHMUK PV R37412. a–d, Photographs (a,b) and 3D model produced from XCT scanning (c,d) showing the specimen in anterior/posterior (a,c) and dorsal (b,d) views. Red lines on a and b indicate where the specimen was sectioned for histological analysis. Red colouration on c and d indicates a cement used to consolidate the specimen. e–g, Thin-section photographs of the rod: full section of the rod (e) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (f) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (g) showing heavily remodelled cortical bone. Yellow box in e indicates the position of f, blue box indicates the position of g. h, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in Spicomellus (f). i, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of Spicomellus (g)." figureDoi="http://doi.org/10.5281/zenodo.5842124" httpUri="https://zenodo.org/record/5842124/files/figure.png" pageId="0" pageNumber="1576">Fig. 1a–d</figureCitation>
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). The specimen was scanned using X-ray Computed Tomography (XCT) to confirm that the spines are co-ossified (
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<figureCitation box="[817,904,1466,1488]" captionStart="Fig" captionStartId="1.[113,143,1216,1236]" captionTargetBox="[263,1349,141,1183]" captionTargetId="figure-377@1.[299,1295,598,1183]" captionTargetPageId="1" captionText="Fig. 1 | Morphology and histology of Spicomellus afer, NHMUK PV R37412. a–d, Photographs (a,b) and 3D model produced from XCT scanning (c,d) showing the specimen in anterior/posterior (a,c) and dorsal (b,d) views. Red lines on a and b indicate where the specimen was sectioned for histological analysis. Red colouration on c and d indicates a cement used to consolidate the specimen. e–g, Thin-section photographs of the rod: full section of the rod (e) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (f) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (g) showing heavily remodelled cortical bone. Yellow box in e indicates the position of f, blue box indicates the position of g. h, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in Spicomellus (f). i, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of Spicomellus (g)." figureDoi="http://doi.org/10.5281/zenodo.5842124" httpUri="https://zenodo.org/record/5842124/files/figure.png" pageId="0" pageNumber="1576">Fig. 1c,d</figureCitation>
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, Extended Data
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<figureCitation box="[1075,1165,1466,1488]" captionStart-0="Fig" captionStart-1="Fig" captionStart-2="Extended" captionStartId-0="1.[113,143,1216,1236]" captionStartId-1="2.[113,143,922,942]" captionStartId-2="8.[113,199,1915,1935]" captionTargetBox-0="[263,1349,141,1183]" captionTargetBox-1="[245,1426,129,889]" captionTargetBox-2="[180,1407,146,1881]" captionTargetId-0="figure-377@1.[299,1295,598,1183]" captionTargetId-2="figure-19@8.[180,1407,146,1881]" captionTargetPageId-0="1" captionTargetPageId-1="2" captionTargetPageId-2="8" captionText-0="Fig. 1 | Morphology and histology of Spicomellus afer, NHMUK PV R37412. a–d, Photographs (a,b) and 3D model produced from XCT scanning (c,d) showing the specimen in anterior/posterior (a,c) and dorsal (b,d) views. Red lines on a and b indicate where the specimen was sectioned for histological analysis. Red colouration on c and d indicates a cement used to consolidate the specimen. e–g, Thin-section photographs of the rod: full section of the rod (e) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (f) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (g) showing heavily remodelled cortical bone. Yellow box in e indicates the position of f, blue box indicates the position of g. h, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in Spicomellus (f). i, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of Spicomellus (g)." captionText-1="Fig. 2 | Details of the histology of Spicomellus afer, NHMUK PV R37142. a,c, Thin-section photographs of the fused rib and osteoderm. The darker region at the top of the image in a and to the top left of the image in c bears the histological characteristics of an osteoderm, while the lighter region below bears histological characteristics of the rib. A strip of structural fibres extending across this interface can be observed in c. b, Thin-section photograph of the spine of NHMUK PV R37142 S. afer showing a cortex of woven bone and an inner core of highly vascularized trabecular bone. d, A section of NHMUK PV R37142 S. afer with the osteoderm and rib sections segmented separately so the morphology of each can be seen. The osteoderm is in blue, while the rib is shown in white." captionText-2="Extended Data Fig. 3 | The osteoderm and rib parts of the rod were segmented using the following procedure. a, a section of the specimen was identified for focus; b, longitudinal sections of the specimen were examined in XCT data; c, the boundary between the osteoderm and the rib was identified on longitudinal sections; d, the data were labelled." figureDoi-0="http://doi.org/10.5281/zenodo.5842124" figureDoi-1="http://doi.org/10.5281/zenodo.5842127" figureDoi-2="http://doi.org/10.5281/zenodo.5842133" httpUri-0="https://zenodo.org/record/5842124/files/figure.png" httpUri-1="https://zenodo.org/record/5842127/files/figure.png" httpUri-2="https://zenodo.org/record/5842133/files/figure.png" pageId="0" pageNumber="1576">Figs. 1–3</figureCitation>
|
||
and Supplementary video). In cross-section, the rod is strongly ‘T’-shaped, with its dorsal, horizontally oriented flange being broader anteroposteriorly (58 mm maximum width) than the depth of its ventral flange (33 mm maximum depth). The dorsal surface of the horizontal flange bears clear fibres that extend along the surface parallel to the rod’s long axis, as well as several fainter fibres extending perpendicular to the clear fibres. The dorsal, anterior and posterior surfaces of the rod are rugose. The horizontal and vertical flanges merge via a concave, smooth surface. The change in texture from the dorsal, rugose horizontal bar to the smooth, featureless ventral flange is marked by a groove that extends for the entire length of the rod.
|
||
</paragraph>
|
||
<caption ID-DOI="http://doi.org/10.5281/zenodo.5842124" ID-Zenodo-Dep="5842124" httpUri="https://zenodo.org/record/5842124/files/figure.png" pageId="1" startId="1.[113,143,1216,1236]" targetBox="[263,1349,141,1183]" targetPageId="1">
|
||
<paragraph blockId="1.[113,1473,1216,1460]" pageId="1">
|
||
<emphasis bold="true" box="[113,811,1216,1237]" pageId="1">
|
||
Fig. 1 | Morphology and histology of
|
||
<taxonomicName authority=", NHMUK PV R" authorityName="NHMUK PV R" box="[439,715,1216,1237]" genus="Spicomellus" pageId="1" rank="species" species="afer">
|
||
<emphasis bold="true" box="[439,581,1219,1237]" italics="true" pageId="1">Spicomellus afer</emphasis>
|
||
, NHMUK PV R
|
||
</taxonomicName>
|
||
37412. a–d
|
||
</emphasis>
|
||
, Photographs (
|
||
<emphasis bold="true" box="[946,957,1216,1236]" pageId="1">a</emphasis>
|
||
,
|
||
<emphasis bold="true" box="[961,973,1216,1236]" pageId="1">b</emphasis>
|
||
) and 3D model produced from XCT scanning (
|
||
<emphasis bold="true" box="[1386,1396,1216,1236]" pageId="1">c</emphasis>
|
||
,
|
||
<emphasis bold="true" box="[1400,1412,1216,1236]" pageId="1">d</emphasis>
|
||
) showing the specimen in anterior/posterior (
|
||
<emphasis bold="true" box="[507,518,1244,1264]" pageId="1">a</emphasis>
|
||
,
|
||
<emphasis bold="true" box="[522,532,1244,1264]" pageId="1">c</emphasis>
|
||
) and dorsal (
|
||
<emphasis bold="true" box="[651,663,1244,1264]" pageId="1">b</emphasis>
|
||
,
|
||
<emphasis bold="true" box="[667,679,1244,1264]" pageId="1">d</emphasis>
|
||
) views. Red lines on
|
||
<emphasis bold="true" box="[863,874,1244,1264]" pageId="1">a</emphasis>
|
||
and
|
||
<emphasis bold="true" box="[916,928,1244,1264]" pageId="1">b</emphasis>
|
||
indicate where the specimen was sectioned for histological analysis. Red colouration on
|
||
<emphasis bold="true" box="[364,374,1272,1292]" pageId="1">c</emphasis>
|
||
and
|
||
<emphasis bold="true" box="[416,428,1272,1292]" pageId="1">d</emphasis>
|
||
indicates a cement used to consolidate the specimen.
|
||
<emphasis bold="true" box="[908,940,1272,1292]" pageId="1">e–g</emphasis>
|
||
, Thin-section photographs of the rod: full section of the rod (
|
||
<emphasis bold="true" box="[122,133,1300,1320]" pageId="1">e</emphasis>
|
||
) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (
|
||
<emphasis bold="true" box="[1015,1022,1300,1320]" pageId="1">f</emphasis>
|
||
) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (
|
||
<emphasis bold="true" box="[814,825,1328,1348]" pageId="1">g</emphasis>
|
||
) showing heavily remodelled cortical bone. Yellow box in
|
||
<emphasis bold="true" box="[1333,1344,1328,1348]" pageId="1">e</emphasis>
|
||
indicates the position of
|
||
<emphasis bold="true" box="[212,219,1356,1376]" pageId="1">f</emphasis>
|
||
, blue box indicates the position of
|
||
<emphasis bold="true" box="[524,535,1356,1376]" pageId="1">g</emphasis>
|
||
.
|
||
<emphasis bold="true" box="[545,556,1356,1376]" pageId="1">h</emphasis>
|
||
, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in
|
||
<taxonomicName box="[1202,1300,1384,1404]" genus="Spicomellus" pageId="1" rank="genus">
|
||
<emphasis box="[1202,1300,1384,1404]" italics="true" pageId="1">Spicomellus</emphasis>
|
||
</taxonomicName>
|
||
(
|
||
<emphasis bold="true" box="[1314,1321,1384,1404]" pageId="1">f</emphasis>
|
||
).
|
||
<emphasis bold="true" box="[1339,1345,1384,1404]" pageId="1">i</emphasis>
|
||
, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of
|
||
<taxonomicName box="[641,739,1440,1460]" genus="Spicomellus" pageId="1" rank="genus">
|
||
<emphasis box="[641,739,1440,1460]" italics="true" pageId="1">Spicomellus</emphasis>
|
||
</taxonomicName>
|
||
(
|
||
<emphasis bold="true" box="[752,763,1440,1460]" pageId="1">g</emphasis>
|
||
).
|
||
</paragraph>
|
||
</caption>
|
||
<paragraph blockId="1.[113,779,1522,1740]" pageId="1">
|
||
The spines are rounded in cross-section and project dorsally (
|
||
<figureCitation box="[120,216,1550,1572]" captionStart="Fig" captionStartId="1.[113,143,1216,1236]" captionTargetBox="[263,1349,141,1183]" captionTargetId="figure-377@1.[299,1295,598,1183]" captionTargetPageId="1" captionText="Fig. 1 | Morphology and histology of Spicomellus afer, NHMUK PV R37412. a–d, Photographs (a,b) and 3D model produced from XCT scanning (c,d) showing the specimen in anterior/posterior (a,c) and dorsal (b,d) views. Red lines on a and b indicate where the specimen was sectioned for histological analysis. Red colouration on c and d indicates a cement used to consolidate the specimen. e–g, Thin-section photographs of the rod: full section of the rod (e) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (f) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (g) showing heavily remodelled cortical bone. Yellow box in e indicates the position of f, blue box indicates the position of g. h, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in Spicomellus (f). i, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of Spicomellus (g)." figureDoi="http://doi.org/10.5281/zenodo.5842124" httpUri="https://zenodo.org/record/5842124/files/figure.png" pageId="1">Fig. 1a–d</figureCitation>
|
||
). The medialmost spine is the smallest and is complete (54 mm from base to tip). As preserved, the second spine is the tallest (97 mm, but missing its distal tip), and the third spine is broken. The fourth spine is angled slightly medially, although this is probably taphonomic distortion (55 mm long, missing its distal tip). The surfaces of the spines are generally smooth, but there is a fine anastomosing mesh of vascular imprints on the external surface.
|
||
</paragraph>
|
||
<paragraph blockId="1.[113,779,1774,1992]" lastBlockId="1.[810,1474,1522,1992]" pageId="1">
|
||
<emphasis bold="true" box="[113,372,1774,1796]" pageId="1">Histological description.</emphasis>
|
||
The spine (
|
||
<figureCitation box="[499,572,1774,1796]" captionStart="Fig" captionStartId="2.[113,143,922,942]" captionTargetBox="[245,1426,129,889]" captionTargetPageId="2" captionText="Fig. 2 | Details of the histology of Spicomellus afer, NHMUK PV R37142. a,c, Thin-section photographs of the fused rib and osteoderm. The darker region at the top of the image in a and to the top left of the image in c bears the histological characteristics of an osteoderm, while the lighter region below bears histological characteristics of the rib. A strip of structural fibres extending across this interface can be observed in c. b, Thin-section photograph of the spine of NHMUK PV R37142 S. afer showing a cortex of woven bone and an inner core of highly vascularized trabecular bone. d, A section of NHMUK PV R37142 S. afer with the osteoderm and rib sections segmented separately so the morphology of each can be seen. The osteoderm is in blue, while the rib is shown in white." figureDoi="http://doi.org/10.5281/zenodo.5842127" httpUri="https://zenodo.org/record/5842127/files/figure.png" pageId="1">Fig. 2b</figureCitation>
|
||
and Extended Data
|
||
<figureCitation box="[113,173,1802,1824]" captionStart="Extended" captionStartId="9.[113,199,1104,1124]" captionTargetBox="[115,1472,148,1071]" captionTargetId="figure-19@9.[115,1472,148,1071]" captionTargetPageId="9" captionText="Extended Data Fig. 4 | Histological thin-section (plane polarized light) showing detail of the spine. A vascular channel can be observed in the top left of the image. The woven bone matrix of the cortex is dominated by primary osteons. Scattered secondary osteons can be observed in the mid and inner cortex. Large resorption cavities lined with lamellar bone can be observed in the trabecular bone of the core (top right). Red arrows indicate growth (=resting) lines." figureDoi="http://doi.org/10.5281/zenodo.5842135" httpUri="https://zenodo.org/record/5842135/files/figure.png" pageId="1">Fig. 4</figureCitation>
|
||
) consists of a ~2.5 mm thick symmetrical cortex of woven bone and an inner core of highly vascularized trabecular bone. Several long pipes
|
||
<bibRefCitation author="de Buffrenil, V. & Farlow, J. O. & de Ricqles, A." box="[295,309,1857,1869]" journalOrPublisher="Paleobiology" pageId="1" pagination="459 - 473" part="12" refId="ref5061" refString="10. de Buffrenil, V., Farlow, J. O. & de Ricqles, A. Growth and function of Stegosaurus plates: evidence from bone histology. Paleobiology 12, 459 - 473 (1986)." title="Growth and function of Stegosaurus plates: evidence from bone histology" type="journal article" year="1986">
|
||
<superScript attach="left" box="[295,309,1857,1869]" fontSize="5" pageId="1">10</superScript>
|
||
</bibRefCitation>
|
||
extend from the core, opening on the surface. A thin layer, which is translucent in plane-polarized light and birefringent under crossed polars, covers much of the outer surface; it includes many scattered small osteocyte lacunae, and is probably diagenetic. Radial vascular canals also open to the bone surface. At least nine growth lines, visible as thin, dark, undulating lines parallel to the bone surface, extend from the central region of the cortex, becoming more closely spaced towards the outer surface. The woven bone matrix of the cortex is dominated by primary osteons with occasional radial and reticular vascular canals in circumferential arrangement. Scattered secondary osteons are present from the inner core to the mid-cortex. The core is composed of trabecular bone and large resorption cavities lined with lamellar bone and occasional secondary osteons. Many small, irregularly arranged osteocyte lacunae with small or no visible processes are scattered throughout the primary bone. Osteocyte lacunae in remodelled bone have a slightly more ovate shape and more extensive processes.
|
||
</paragraph>
|
||
<paragraph blockId="1.[810,1474,1522,1992]" lastBlockId="2.[113,778,1158,1880]" lastPageId="2" pageId="1">
|
||
The horizontal bar of the rod is composed of two distinct histologies (
|
||
<figureCitation box="[873,974,1886,1908]" captionStart="Fig" captionStartId="1.[113,143,1216,1236]" captionTargetBox="[263,1349,141,1183]" captionTargetId="figure-377@1.[299,1295,598,1183]" captionTargetPageId="1" captionText="Fig. 1 | Morphology and histology of Spicomellus afer, NHMUK PV R37412. a–d, Photographs (a,b) and 3D model produced from XCT scanning (c,d) showing the specimen in anterior/posterior (a,c) and dorsal (b,d) views. Red lines on a and b indicate where the specimen was sectioned for histological analysis. Red colouration on c and d indicates a cement used to consolidate the specimen. e–g, Thin-section photographs of the rod: full section of the rod (e) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (f) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (g) showing heavily remodelled cortical bone. Yellow box in e indicates the position of f, blue box indicates the position of g. h, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in Spicomellus (f). i, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of Spicomellus (g)." figureDoi="http://doi.org/10.5281/zenodo.5842124" httpUri="https://zenodo.org/record/5842124/files/figure.png" pageId="1">Figs. 1e–g</figureCitation>
|
||
and
|
||
<figureCitation box="[1022,1061,1886,1907]" captionStart="Fig" captionStartId="2.[113,143,922,942]" captionTargetBox="[245,1426,129,889]" captionTargetPageId="2" captionText="Fig. 2 | Details of the histology of Spicomellus afer, NHMUK PV R37142. a,c, Thin-section photographs of the fused rib and osteoderm. The darker region at the top of the image in a and to the top left of the image in c bears the histological characteristics of an osteoderm, while the lighter region below bears histological characteristics of the rib. A strip of structural fibres extending across this interface can be observed in c. b, Thin-section photograph of the spine of NHMUK PV R37142 S. afer showing a cortex of woven bone and an inner core of highly vascularized trabecular bone. d, A section of NHMUK PV R37142 S. afer with the osteoderm and rib sections segmented separately so the morphology of each can be seen. The osteoderm is in blue, while the rib is shown in white." figureDoi="http://doi.org/10.5281/zenodo.5842127" httpUri="https://zenodo.org/record/5842127/files/figure.png" pageId="1">2a,c</figureCitation>
|
||
). Its upper and lower sections are divided by a strip of structural fibres (mineralized collagenous fibres not associated with ligamentous or tendinous insertion
|
||
<bibRefCitation author="Scheyer, T. M. & Sander, P. M." box="[1329,1343,1941,1953]" journalOrPublisher="J. Vertebr. Paleontol." pageId="1" pagination="874 - 893" part="24" refId="ref5103" refString="11. Scheyer, T. M. & Sander, P. M. Histology of ankylosaur osteoderms: implications for systematics and function. J. Vertebr. Paleontol. 24, 874 - 893 (2004)." title="Histology of ankylosaur osteoderms: implications for systematics and function" type="journal article" year="2004">
|
||
<superScript attach="left" box="[1329,1343,1941,1953]" fontSize="5" pageId="1">11</superScript>
|
||
</bibRefCitation>
|
||
) that extend across the width of the section (
|
||
<figureCitation box="[1133,1211,1970,1992]" captionStart="Fig" captionStartId="1.[113,143,1216,1236]" captionTargetBox="[263,1349,141,1183]" captionTargetId="figure-377@1.[299,1295,598,1183]" captionTargetPageId="1" captionText="Fig. 1 | Morphology and histology of Spicomellus afer, NHMUK PV R37412. a–d, Photographs (a,b) and 3D model produced from XCT scanning (c,d) showing the specimen in anterior/posterior (a,c) and dorsal (b,d) views. Red lines on a and b indicate where the specimen was sectioned for histological analysis. Red colouration on c and d indicates a cement used to consolidate the specimen. e–g, Thin-section photographs of the rod: full section of the rod (e) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (f) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (g) showing heavily remodelled cortical bone. Yellow box in e indicates the position of f, blue box indicates the position of g. h, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in Spicomellus (f). i, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of Spicomellus (g)." figureDoi="http://doi.org/10.5281/zenodo.5842124" httpUri="https://zenodo.org/record/5842124/files/figure.png" pageId="1">Figs. 1e</figureCitation>
|
||
and
|
||
<figureCitation box="[1263,1302,1970,1991]" captionStart="Fig" captionStartId="2.[113,143,922,942]" captionTargetBox="[245,1426,129,889]" captionTargetPageId="2" captionText="Fig. 2 | Details of the histology of Spicomellus afer, NHMUK PV R37142. a,c, Thin-section photographs of the fused rib and osteoderm. The darker region at the top of the image in a and to the top left of the image in c bears the histological characteristics of an osteoderm, while the lighter region below bears histological characteristics of the rib. A strip of structural fibres extending across this interface can be observed in c. b, Thin-section photograph of the spine of NHMUK PV R37142 S. afer showing a cortex of woven bone and an inner core of highly vascularized trabecular bone. d, A section of NHMUK PV R37142 S. afer with the osteoderm and rib sections segmented separately so the morphology of each can be seen. The osteoderm is in blue, while the rib is shown in white." figureDoi="http://doi.org/10.5281/zenodo.5842127" httpUri="https://zenodo.org/record/5842127/files/figure.png" pageId="1">2a,c</figureCitation>
|
||
). The upper half of the rod is dominated by an ordered pattern of structural fibres, which are arranged in regular, orthogonal plywood-like layers
|
||
<bibRefCitation author="Scheyer, T. M. & Sander, P. M. & Joyce, W. G. & Bohme, W. & Witzel, U." box="[764,778,1185,1197]" journalOrPublisher="Org. Divers. Evol." pageId="2" pagination="136 - 144" part="7" refId="ref5144" refString="12. Scheyer, T. M., Sander, P. M., Joyce, W. G., Bohme, W. & Witzel, U. A plywood structure in the shell of fossil and living soft-shelled turtles (Trionychidae) and its evolutionary implications. Org. Divers. Evol. 7, 136 - 144 (2007)." title="A plywood structure in the shell of fossil and living soft-shelled turtles (Trionychidae) and its evolutionary implications" type="journal article" year="2007">
|
||
<superScript attach="left" box="[764,778,1185,1197]" fontSize="5" pageId="2">12</superScript>
|
||
</bibRefCitation>
|
||
that cross each other at approximately 90° and overlie the primary bone matrix. The fibres, visible as darker and lighter strands or bundles under polarized light (
|
||
<figureCitation box="[429,495,1270,1292]" captionStart="Fig" captionStartId="1.[113,143,1216,1236]" captionTargetBox="[263,1349,141,1183]" captionTargetId="figure-377@1.[299,1295,598,1183]" captionTargetPageId="1" captionText="Fig. 1 | Morphology and histology of Spicomellus afer, NHMUK PV R37412. a–d, Photographs (a,b) and 3D model produced from XCT scanning (c,d) showing the specimen in anterior/posterior (a,c) and dorsal (b,d) views. Red lines on a and b indicate where the specimen was sectioned for histological analysis. Red colouration on c and d indicates a cement used to consolidate the specimen. e–g, Thin-section photographs of the rod: full section of the rod (e) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (f) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (g) showing heavily remodelled cortical bone. Yellow box in e indicates the position of f, blue box indicates the position of g. h, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in Spicomellus (f). i, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of Spicomellus (g)." figureDoi="http://doi.org/10.5281/zenodo.5842124" httpUri="https://zenodo.org/record/5842124/files/figure.png" pageId="2">Fig. 1f</figureCitation>
|
||
and Extended Data
|
||
<figureCitation box="[706,765,1270,1292]" captionStart="Extended" captionStartId="10.[113,199,1086,1106]" captionTargetBox="[115,1472,148,1053]" captionTargetId="figure-19@10.[115,1472,148,1053]" captionTargetPageId="10" captionText="Extended Data Fig. 5 | Thin section photomicrograph (plane-polarized light) showing detail of the structural fibres in the upper osteodermal part of the rod. Structural fibre bundles intersect roughly perpendicular to each other. The opaque cast in the top half of the image is probably diagenetic alteration." figureDoi="http://doi.org/10.5281/zenodo.5842137" httpUri="https://zenodo.org/record/5842137/files/figure.png" pageId="2">Fig. 5</figureCitation>
|
||
), are arranged approximately perpendicular and parallel to the bone surface and follow the curvature of the bone at its outer edges (
|
||
<figureCitation box="[120,189,1354,1376]" captionStart="Fig" captionStartId="2.[113,143,922,942]" captionTargetBox="[245,1426,129,889]" captionTargetPageId="2" captionText="Fig. 2 | Details of the histology of Spicomellus afer, NHMUK PV R37142. a,c, Thin-section photographs of the fused rib and osteoderm. The darker region at the top of the image in a and to the top left of the image in c bears the histological characteristics of an osteoderm, while the lighter region below bears histological characteristics of the rib. A strip of structural fibres extending across this interface can be observed in c. b, Thin-section photograph of the spine of NHMUK PV R37142 S. afer showing a cortex of woven bone and an inner core of highly vascularized trabecular bone. d, A section of NHMUK PV R37142 S. afer with the osteoderm and rib sections segmented separately so the morphology of each can be seen. The osteoderm is in blue, while the rib is shown in white." figureDoi="http://doi.org/10.5281/zenodo.5842127" httpUri="https://zenodo.org/record/5842127/files/figure.png" pageId="2">Fig. 2a</figureCitation>
|
||
). The fibre bundles are 500–600 µm thick and the majority are not interwoven. Simple vascular canals and some primary osteons with occasional radial and reticular vascular canals can be seen in the small sections of primary bone matrix that are not obscured by the fibre bundles (
|
||
<figureCitation box="[431,497,1466,1488]" captionStart="Fig" captionStartId="1.[113,143,1216,1236]" captionTargetBox="[263,1349,141,1183]" captionTargetId="figure-377@1.[299,1295,598,1183]" captionTargetPageId="1" captionText="Fig. 1 | Morphology and histology of Spicomellus afer, NHMUK PV R37412. a–d, Photographs (a,b) and 3D model produced from XCT scanning (c,d) showing the specimen in anterior/posterior (a,c) and dorsal (b,d) views. Red lines on a and b indicate where the specimen was sectioned for histological analysis. Red colouration on c and d indicates a cement used to consolidate the specimen. e–g, Thin-section photographs of the rod: full section of the rod (e) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (f) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (g) showing heavily remodelled cortical bone. Yellow box in e indicates the position of f, blue box indicates the position of g. h, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in Spicomellus (f). i, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of Spicomellus (g)." figureDoi="http://doi.org/10.5281/zenodo.5842124" httpUri="https://zenodo.org/record/5842124/files/figure.png" pageId="2">Fig. 1f</figureCitation>
|
||
). Small, irregular osteocyte lacunae with short or no visible processes are present.
|
||
</paragraph>
|
||
<caption ID-DOI="http://doi.org/10.5281/zenodo.5842127" ID-Zenodo-Dep="5842127" httpUri="https://zenodo.org/record/5842127/files/figure.png" pageId="2" startId="2.[113,143,922,942]" targetBox="[245,1426,129,889]" targetPageId="2">
|
||
<paragraph blockId="2.[113,1471,922,1082]" pageId="2">
|
||
<emphasis bold="true" box="[113,768,922,942]" pageId="2">
|
||
Fig. 2 | Details of the histology of
|
||
<taxonomicName authority=", NHMUK PV R" authorityName="NHMUK PV R" box="[414,692,922,942]" genus="Spicomellus" pageId="2" rank="species" species="afer">
|
||
<emphasis bold="true" box="[414,557,924,942]" italics="true" pageId="2">Spicomellus afer</emphasis>
|
||
, NHMUK PV R
|
||
</taxonomicName>
|
||
37142. a
|
||
</emphasis>
|
||
,
|
||
<emphasis bold="true" box="[772,782,922,942]" pageId="2">c</emphasis>
|
||
, Thin-section photographs of the fused rib and osteoderm. The darker region at the top of the image in
|
||
<emphasis bold="true" box="[339,350,950,970]" pageId="2">a</emphasis>
|
||
and to the top left of the image in
|
||
<emphasis bold="true" box="[652,662,950,970]" pageId="2">c</emphasis>
|
||
bears the histological characteristics of an osteoderm, while the lighter region below bears histological characteristics of the rib. A strip of structural fibres extending across this interface can be observed in
|
||
<emphasis bold="true" box="[1117,1127,978,998]" pageId="2">c</emphasis>
|
||
.
|
||
<emphasis bold="true" box="[1136,1148,978,998]" pageId="2">b</emphasis>
|
||
, Thin-section photograph of the spine of NHMUK PV R37142
|
||
<taxonomicName box="[371,423,1006,1026]" genus="Spicomellus" pageId="2" rank="species" species="afer">
|
||
<emphasis box="[371,423,1006,1026]" italics="true" pageId="2">S. afer</emphasis>
|
||
</taxonomicName>
|
||
showing a cortex of woven bone and an inner core of highly vascularized trabecular bone.
|
||
<emphasis bold="true" box="[1216,1228,1006,1026]" pageId="2">d</emphasis>
|
||
, A section of NHMUK PV R37142
|
||
<taxonomicName box="[184,236,1034,1054]" genus="Spicomellus" pageId="2" rank="species" species="afer">
|
||
<emphasis box="[184,236,1034,1054]" italics="true" pageId="2">S. afer</emphasis>
|
||
</taxonomicName>
|
||
with the osteoderm and rib sections segmented separately so the morphology of each can be seen. The osteoderm is in blue, while the rib is shown in white.
|
||
</paragraph>
|
||
</caption>
|
||
<paragraph blockId="2.[113,778,1158,1880]" pageId="2">
|
||
By contrast, the lower section of the horizontal bar and the vertical flange are composed of highly vascularized, remodelled woven bone with no structural fibres (
|
||
<figureCitation box="[432,511,1578,1600]" captionStart="Fig" captionStartId="1.[113,143,1216,1236]" captionTargetBox="[263,1349,141,1183]" captionTargetId="figure-377@1.[299,1295,598,1183]" captionTargetPageId="1" captionText="Fig. 1 | Morphology and histology of Spicomellus afer, NHMUK PV R37412. a–d, Photographs (a,b) and 3D model produced from XCT scanning (c,d) showing the specimen in anterior/posterior (a,c) and dorsal (b,d) views. Red lines on a and b indicate where the specimen was sectioned for histological analysis. Red colouration on c and d indicates a cement used to consolidate the specimen. e–g, Thin-section photographs of the rod: full section of the rod (e) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (f) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (g) showing heavily remodelled cortical bone. Yellow box in e indicates the position of f, blue box indicates the position of g. h, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in Spicomellus (f). i, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of Spicomellus (g)." figureDoi="http://doi.org/10.5281/zenodo.5842124" httpUri="https://zenodo.org/record/5842124/files/figure.png" pageId="2">Figs. 1g</figureCitation>
|
||
and
|
||
<figureCitation box="[564,587,1578,1599]" captionStart="Fig" captionStartId="2.[113,143,922,942]" captionTargetBox="[245,1426,129,889]" captionTargetPageId="2" captionText="Fig. 2 | Details of the histology of Spicomellus afer, NHMUK PV R37142. a,c, Thin-section photographs of the fused rib and osteoderm. The darker region at the top of the image in a and to the top left of the image in c bears the histological characteristics of an osteoderm, while the lighter region below bears histological characteristics of the rib. A strip of structural fibres extending across this interface can be observed in c. b, Thin-section photograph of the spine of NHMUK PV R37142 S. afer showing a cortex of woven bone and an inner core of highly vascularized trabecular bone. d, A section of NHMUK PV R37142 S. afer with the osteoderm and rib sections segmented separately so the morphology of each can be seen. The osteoderm is in blue, while the rib is shown in white." figureDoi="http://doi.org/10.5281/zenodo.5842127" httpUri="https://zenodo.org/record/5842127/files/figure.png" pageId="2">2a</figureCitation>
|
||
). Growth lines are visible near the outer surface. Small, simple vascular canals are present in a circumferential arrangement parallel to the outer surface, followed by a ring of larger primary osteons and then either a sharp transition or smooth gradation to a highly vascularized region populated by resorption cavities with lamellar bone infill forming trabeculae with a high degree of remodelling (
|
||
<figureCitation box="[580,658,1746,1768]" captionStart="Fig" captionStartId="1.[113,143,1216,1236]" captionTargetBox="[263,1349,141,1183]" captionTargetId="figure-377@1.[299,1295,598,1183]" captionTargetPageId="1" captionText="Fig. 1 | Morphology and histology of Spicomellus afer, NHMUK PV R37412. a–d, Photographs (a,b) and 3D model produced from XCT scanning (c,d) showing the specimen in anterior/posterior (a,c) and dorsal (b,d) views. Red lines on a and b indicate where the specimen was sectioned for histological analysis. Red colouration on c and d indicates a cement used to consolidate the specimen. e–g, Thin-section photographs of the rod: full section of the rod (e) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (f) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (g) showing heavily remodelled cortical bone. Yellow box in e indicates the position of f, blue box indicates the position of g. h, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in Spicomellus (f). i, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of Spicomellus (g)." figureDoi="http://doi.org/10.5281/zenodo.5842124" httpUri="https://zenodo.org/record/5842124/files/figure.png" pageId="2">Figs. 1g</figureCitation>
|
||
and
|
||
<figureCitation box="[710,733,1746,1767]" captionStart="Fig" captionStartId="2.[113,143,922,942]" captionTargetBox="[245,1426,129,889]" captionTargetPageId="2" captionText="Fig. 2 | Details of the histology of Spicomellus afer, NHMUK PV R37142. a,c, Thin-section photographs of the fused rib and osteoderm. The darker region at the top of the image in a and to the top left of the image in c bears the histological characteristics of an osteoderm, while the lighter region below bears histological characteristics of the rib. A strip of structural fibres extending across this interface can be observed in c. b, Thin-section photograph of the spine of NHMUK PV R37142 S. afer showing a cortex of woven bone and an inner core of highly vascularized trabecular bone. d, A section of NHMUK PV R37142 S. afer with the osteoderm and rib sections segmented separately so the morphology of each can be seen. The osteoderm is in blue, while the rib is shown in white." figureDoi="http://doi.org/10.5281/zenodo.5842127" httpUri="https://zenodo.org/record/5842127/files/figure.png" pageId="2">2a</figureCitation>
|
||
). At least three generations of secondary osteons are present (
|
||
<figureCitation box="[693,763,1774,1796]" captionStart="Fig" captionStartId="1.[113,143,1216,1236]" captionTargetBox="[263,1349,141,1183]" captionTargetId="figure-377@1.[299,1295,598,1183]" captionTargetPageId="1" captionText="Fig. 1 | Morphology and histology of Spicomellus afer, NHMUK PV R37412. a–d, Photographs (a,b) and 3D model produced from XCT scanning (c,d) showing the specimen in anterior/posterior (a,c) and dorsal (b,d) views. Red lines on a and b indicate where the specimen was sectioned for histological analysis. Red colouration on c and d indicates a cement used to consolidate the specimen. e–g, Thin-section photographs of the rod: full section of the rod (e) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (f) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (g) showing heavily remodelled cortical bone. Yellow box in e indicates the position of f, blue box indicates the position of g. h, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in Spicomellus (f). i, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of Spicomellus (g)." figureDoi="http://doi.org/10.5281/zenodo.5842124" httpUri="https://zenodo.org/record/5842124/files/figure.png" pageId="2">Fig. 1g</figureCitation>
|
||
). Many small osteocyte lacunae are present with short or no visible processes, whereas the osteocyte lacunae in remodelled bone are more ovate with more extensive processes.
|
||
</paragraph>
|
||
<paragraph blockId="2.[113,778,1914,1992]" lastBlockId="2.[810,1475,1157,1992]" pageId="2">
|
||
<emphasis bold="true" box="[113,323,1914,1936]" pageId="2">Taxonomic identity.</emphasis>
|
||
Given its unique anatomy, we considered a non-tetrapod osteichthyan affinity for NHMUK PV R37412, but rejected this hypothesis for several reasons. First, the specimen was found in a terrestrial sedimentary sequence
|
||
<bibRefCitation author="Maidment, S. C. R. & Raven, T. J. & Ouarhache, D. & Barrett, P. M." box="[1294,1301,1157,1169]" journalOrPublisher="Gondwana Res." pageId="2" pagination="82 - 97" part="77" refId="ref4800" refString="4. Maidment, S. C. R., Raven, T. J., Ouarhache, D. & Barrett, P. M. North Africa's first stegosaur: implications for Gondwanan thyreophoran dinosaur diversity. Gondwana Res. 77, 82 - 97 (2020)." title="North Africa's first stegosaur: implications for Gondwanan thyreophoran dinosaur diversity" type="journal article" year="2020">
|
||
<superScript attach="left" box="[1294,1301,1157,1169]" fontSize="5" pageId="2">4</superScript>
|
||
</bibRefCitation>
|
||
, which seems an unlikely source for what would have been an exceptionally large fish, but exclusion is also possible based on histological criteria. Teeth are ankylosed to the jaw in a range of osteichthyan fishes
|
||
<bibRefCitation author="Berkovitz, B. & Shellis, R. P." box="[1454,1468,1241,1253]" journalOrPublisher="Academic Press" pageId="2" refId="ref5211" refString="13. Berkovitz, B. & Shellis, R. P. The Teeth of Non-mammalian Vertebrates (Academic Press, 2017)." title="The Teeth of Non-mammalian Vertebrates" type="book" year="2017">
|
||
<superScript attach="left" box="[1454,1468,1241,1253]" fontSize="5" pageId="2">13</superScript>
|
||
</bibRefCitation>
|
||
, similar to the way the spikes are fused to the rod in NHMUK PV R37412. However, fish teeth are usually composed of orthodentine surrounding a pulp cavity, with characteristic elongate odontoblast tubules extending through the dentine
|
||
<bibRefCitation author="Berkovitz, B. & Shellis, R. P." box="[1216,1230,1353,1365]" journalOrPublisher="Academic Press" pageId="2" refId="ref5211" refString="13. Berkovitz, B. & Shellis, R. P. The Teeth of Non-mammalian Vertebrates (Academic Press, 2017)." title="The Teeth of Non-mammalian Vertebrates" type="book" year="2017">
|
||
<superScript attach="left" box="[1216,1230,1353,1365]" fontSize="5" pageId="2">13</superScript>
|
||
</bibRefCitation>
|
||
. Several chondrichthyans
|
||
<superScript attach="left" box="[843,878,1381,1393]" fontSize="5" pageId="2">
|
||
<bibRefCitation author="Schnetz, L. & Pfaff, C. & Kriwet, J." box="[843,857,1381,1393]" journalOrPublisher="J. Morphol." pageId="2" pagination="1584 - 1598" part="277" refId="ref5236" refString="14. Schnetz, L., Pfaff, C. & Kriwet, J. Tooth development and histology patterns in lamniform sharks (Elasmobranchii, Lamniformes) revisited. J. Morphol. 277, 1584 - 1598 (2016)." title="Tooth development and histology patterns in lamniform sharks (Elasmobranchii, Lamniformes) revisited" type="journal article" year="2016">14</bibRefCitation>
|
||
–
|
||
<bibRefCitation author="Jambura, P. L. & et al." box="[864,878,1381,1393]" journalOrPublisher="J. Anat." pageId="2" pagination="753 - 771" part="236" refId="ref5326" refString="16. Jambura, P. L. et al. Evolutionary trajectories of tooth histology patterns in modern sharks (Chondrichthyes, Elasmobranchii). J. Anat. 236, 753 - 771 (2020)." title="Evolutionary trajectories of tooth histology patterns in modern sharks (Chondrichthyes, Elasmobranchii)" type="journal article" year="2020">16</bibRefCitation>
|
||
</superScript>
|
||
and a few osteichthyans
|
||
<bibRefCitation author="Berkovitz, B. & Shellis, R. P." box="[1127,1141,1381,1393]" journalOrPublisher="Academic Press" pageId="2" refId="ref5211" refString="13. Berkovitz, B. & Shellis, R. P. The Teeth of Non-mammalian Vertebrates (Academic Press, 2017)." title="The Teeth of Non-mammalian Vertebrates" type="book" year="2017">
|
||
<superScript attach="left" box="[1127,1141,1381,1393]" fontSize="5" pageId="2">13</superScript>
|
||
</bibRefCitation>
|
||
have trabecular bone-like osteodentine within the pulp cavity, but in the latter this is generally surrounded by a pallial layer of orthodentine. However, there is no histological evidence of orthodentine in the specimen and other aspects of its histology and morphology favour a tetrapod origin.
|
||
</paragraph>
|
||
<paragraph blockId="2.[810,1475,1157,1992]" pageId="2">
|
||
Osteoderms are thought to form via metaplasia, a specific case of intramembranous ossification
|
||
<superScript attach="left" box="[1140,1189,1549,1561]" fontSize="5" pageId="2">
|
||
<bibRefCitation author="Scheyer, T. M. & Sander, P. M." box="[1140,1154,1549,1561]" journalOrPublisher="J. Vertebr. Paleontol." pageId="2" pagination="874 - 893" part="24" refId="ref5103" refString="11. Scheyer, T. M. & Sander, P. M. Histology of ankylosaur osteoderms: implications for systematics and function. J. Vertebr. Paleontol. 24, 874 - 893 (2004)." title="Histology of ankylosaur osteoderms: implications for systematics and function" type="journal article" year="2004">11</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Reid, R. E. H." box="[1158,1172,1549,1561]" journalOrPublisher="BYU Geol. Stud." pageId="2" pagination="25 - 72" part="41" refId="ref5365" refString="17. Reid, R. E. H. Bone histology of the Cleveland-Lloyd dinosaurs and of dinosaurs in general, part 1: introduction to bone tissues. BYU Geol. Stud. 41, 25 - 72 (1996)." title="Bone histology of the Cleveland-Lloyd dinosaurs and of dinosaurs in general, part 1: introduction to bone tissues" type="journal article" year="1996">17</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Main, R. P. & de Ricqles, A. & Horner, J. R. & Padian, K." box="[1175,1189,1549,1561]" journalOrPublisher="Paleobiology" pageId="2" pagination="291 - 314" part="31" refId="ref5409" refString="18. Main, R. P., de Ricqles, A., Horner, J. R. & Padian, K. The evolution and function of thyreophoran dinosaur scutes: implications for plate function in stegosaurs. Paleobiology 31, 291 - 314 (2005)." title="The evolution and function of thyreophoran dinosaur scutes: implications for plate function in stegosaurs" type="journal article" year="2005">18</bibRefCitation>
|
||
</superScript>
|
||
but see
|
||
<bibRefCitation author="Dubansky, B. H. & Dubansky, B. D." box="[1272,1286,1549,1561]" journalOrPublisher="Anat. Rec." pageId="2" pagination="56 - 76" part="301" refId="ref5461" refString="19. Dubansky, B. H. & Dubansky, B. D. Natural development of dermal ectopic bone in the American alligator (Alligator mississippiensis) resembles heterotopic ossification disorders in humans. Anat. Rec. 301, 56 - 76 (2018)." title="Natural development of dermal ectopic bone in the American alligator (Alligator mississippiensis) resembles heterotopic ossification disorders in humans" type="journal article" year="2018">
|
||
<superScript attach="left" box="[1272,1286,1549,1561]" fontSize="5" pageId="2">19</superScript>
|
||
</bibRefCitation>
|
||
. Metaplastic bone typically has low levels of vascularity and small or no osteocyte lacunae that lack visible processes
|
||
<superScript attach="right" box="[1150,1181,1605,1617]" fontSize="5" pageId="2">
|
||
<bibRefCitation author="Reid, R. E. H." box="[1150,1164,1605,1617]" journalOrPublisher="BYU Geol. Stud." pageId="2" pagination="25 - 72" part="41" refId="ref5365" refString="17. Reid, R. E. H. Bone histology of the Cleveland-Lloyd dinosaurs and of dinosaurs in general, part 1: introduction to bone tissues. BYU Geol. Stud. 41, 25 - 72 (1996)." title="Bone histology of the Cleveland-Lloyd dinosaurs and of dinosaurs in general, part 1: introduction to bone tissues" type="journal article" year="1996">17</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Main, R. P. & de Ricqles, A. & Horner, J. R. & Padian, K." box="[1167,1181,1605,1617]" journalOrPublisher="Paleobiology" pageId="2" pagination="291 - 314" part="31" refId="ref5409" refString="18. Main, R. P., de Ricqles, A., Horner, J. R. & Padian, K. The evolution and function of thyreophoran dinosaur scutes: implications for plate function in stegosaurs. Paleobiology 31, 291 - 314 (2005)." title="The evolution and function of thyreophoran dinosaur scutes: implications for plate function in stegosaurs" type="journal article" year="2005">18</bibRefCitation>
|
||
</superScript>
|
||
. Bone formed via metaplasia from the dermis often exhibits extensive fibre patterns reflecting the incorporation of collagen fibres from the original extracellular matrix
|
||
<superScript attach="left" box="[876,924,1689,1701]" fontSize="5" pageId="2">
|
||
<bibRefCitation author="Scheyer, T. M. & Sander, P. M." box="[876,890,1689,1701]" journalOrPublisher="J. Vertebr. Paleontol." pageId="2" pagination="874 - 893" part="24" refId="ref5103" refString="11. Scheyer, T. M. & Sander, P. M. Histology of ankylosaur osteoderms: implications for systematics and function. J. Vertebr. Paleontol. 24, 874 - 893 (2004)." title="Histology of ankylosaur osteoderms: implications for systematics and function" type="journal article" year="2004">11</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Main, R. P. & de Ricqles, A. & Horner, J. R. & Padian, K." box="[893,907,1689,1701]" journalOrPublisher="Paleobiology" pageId="2" pagination="291 - 314" part="31" refId="ref5409" refString="18. Main, R. P., de Ricqles, A., Horner, J. R. & Padian, K. The evolution and function of thyreophoran dinosaur scutes: implications for plate function in stegosaurs. Paleobiology 31, 291 - 314 (2005)." title="The evolution and function of thyreophoran dinosaur scutes: implications for plate function in stegosaurs" type="journal article" year="2005">18</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Kirby, A. & et al." box="[910,924,1689,1701]" journalOrPublisher="J. Anat." pageId="2" pagination="1035 - 1043" part="236" refId="ref5510" refString="20. Kirby, A. et al. A comparative histological study of the osteoderms in the lizards Heloderma suspectum (Squamata: Helodermatidae) and Varanus komodoensis (Squamata: Varanidae). J. Anat. 236, 1035 - 1043 (2020)." title="A comparative histological study of the osteoderms in the lizards Heloderma suspectum (Squamata: Helodermatidae) and Varanus komodoensis (Squamata: Varanidae)" type="journal article" year="2020">20</bibRefCitation>
|
||
</superScript>
|
||
. The presence of extensive structural fibre bundles in the upper part of the horizontal bar strongly suggests that it is an osteoderm formed via intramembranous ossification within the stratum compactum, and indicates that the skin would have been reinforced with thick striations of structural fibres, adding strength and tear resistance
|
||
<bibRefCitation author="Shadwick, R. E. & Russell, A. P. & Lauff, R. F." box="[992,1006,1829,1841]" journalOrPublisher="Philos. Trans. R. Soc. Lond. B" pageId="2" pagination="419 - 428" part="337" refId="ref5558" refString="21. Shadwick, R. E., Russell, A. P. & Lauff, R. F. The structure and mechanical design of rhinoceros dermal armour. Philos. Trans. R. Soc. Lond. B 337, 419 - 428 (1992)." title="The structure and mechanical design of rhinoceros dermal armour" type="journal article" year="1992">
|
||
<superScript attach="left" box="[992,1006,1829,1841]" fontSize="5" pageId="2">21</superScript>
|
||
</bibRefCitation>
|
||
. The lower part of the rod bears the histological characteristics of tetrapod postcranial bone
|
||
<bibRefCitation author="Hall, B. K." box="[1249,1263,1857,1869]" journalOrPublisher="Elsevier" pageId="2" refId="ref5610" refString="22. Hall, B. K. Bones and Cartilage, Development and Evolutionary Skeletal Biology (Elsevier, 2015)." title="Bones and Cartilage, Development and Evolutionary Skeletal Biology" type="book" year="2015">
|
||
<superScript attach="left" box="[1249,1263,1857,1869]" fontSize="5" pageId="2">22</superScript>
|
||
</bibRefCitation>
|
||
, and is morphologically consistent with being a dorsal rib.
|
||
</paragraph>
|
||
<paragraph blockId="2.[810,1475,1157,1992]" lastBlockId="3.[113,779,150,1320]" lastPageId="3" pageId="2">
|
||
Consequently, we conclude that NHMUK PV R37412 is a dorsal rib with an osteoderm fused to its external surface (
|
||
<figureCitation box="[1387,1460,1942,1964]" captionStart="Fig" captionStartId="2.[113,143,922,942]" captionTargetBox="[245,1426,129,889]" captionTargetPageId="2" captionText="Fig. 2 | Details of the histology of Spicomellus afer, NHMUK PV R37142. a,c, Thin-section photographs of the fused rib and osteoderm. The darker region at the top of the image in a and to the top left of the image in c bears the histological characteristics of an osteoderm, while the lighter region below bears histological characteristics of the rib. A strip of structural fibres extending across this interface can be observed in c. b, Thin-section photograph of the spine of NHMUK PV R37142 S. afer showing a cortex of woven bone and an inner core of highly vascularized trabecular bone. d, A section of NHMUK PV R37142 S. afer with the osteoderm and rib sections segmented separately so the morphology of each can be seen. The osteoderm is in blue, while the rib is shown in white." figureDoi="http://doi.org/10.5281/zenodo.5842127" httpUri="https://zenodo.org/record/5842127/files/figure.png" pageId="2">Fig. 2d</figureCitation>
|
||
). The morphological and histological characteristics of NHMUK PV R37412, along with its age, suggest referral to Ankylosauria. Possession of dorsal ribs that are ‘T’-shaped in cross-section in their proximal portions is a synapomorphy of Eurypoda (Stegosa uria + Ankylosauria)
|
||
<superScript attach="none" box="[318,343,233,245]" fontSize="5" pageId="3">
|
||
<bibRefCitation author="Vickaryous, M. K. & Maryanska, T. & Weishampel, D. B." box="[318,325,233,245]" editor="Weishampel, D. B." journalOrPublisher="Univ. California Press" pageId="3" pagination="363 - 392" refId="ref4661" refString="1. Vickaryous, M. K., Maryanska, T. & Weishampel, D. B. in The Dinosauria (eds Weishampel, D. B. et al.) 363 - 392 (Univ. California Press, 2004)." type="book chapter" volumeTitle="The Dinosauria" year="2004">1</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Galton, P. M. & Upchurch, P." box="[329,343,233,245]" editor="Weishampel, D. B. & et al." journalOrPublisher="Univ. California Press" pageId="3" pagination="343 - 362" refId="ref5633" refString="23. Galton, P. M. & Upchurch, P. in The Dinosauria (eds Weishampel, D. B. et al.) 343 - 362 (Univ. California Press, 2004)." type="book chapter" volumeTitle="The Dinosauria" year="2004">23</bibRefCitation>
|
||
</superScript>
|
||
, allowing confident referral to the clade. Among eurypodans, the interwoven, plywood-like arrangement of structural fibres observed in this specimen has previously been described in numerous ankylosaurs
|
||
<superScript attach="left" box="[474,523,317,329]" fontSize="5" pageId="3">
|
||
<bibRefCitation author="Scheyer, T. M. & Sander, P. M." box="[474,488,317,329]" journalOrPublisher="J. Vertebr. Paleontol." pageId="3" pagination="874 - 893" part="24" refId="ref5103" refString="11. Scheyer, T. M. & Sander, P. M. Histology of ankylosaur osteoderms: implications for systematics and function. J. Vertebr. Paleontol. 24, 874 - 893 (2004)." title="Histology of ankylosaur osteoderms: implications for systematics and function" type="journal article" year="2004">11</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Barrett, P. M. & Clarke, J. B. & Brinkman, D. B. & Chapman, S. D. & Ensom, P. C." box="[491,505,317,329]" journalOrPublisher="Cretac. Res." pageId="3" pagination="279 - 295" part="23" refId="ref5673" refString="24. Barrett, P. M., Clarke, J. B., Brinkman, D. B., Chapman, S. D. & Ensom, P. C. Morphology, histology and identification of the ' granicones' from the Purbeck Limestone Formation (Lower Cretaceous: Berriasian) of Dorset, southern England. Cretac. Res. 23, 279 - 295 (2002)." title="Morphology, histology and identification of the ' granicones' from the Purbeck Limestone Formation (Lower Cretaceous: Berriasian) of Dorset, southern England" type="journal article" year="2002">24</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Burns, M. E. & Currie, P. J." box="[509,523,317,329]" journalOrPublisher="J. Vertebr. Paleontol." pageId="3" pagination="835 - 851" part="34" refId="ref5748" refString="25. Burns, M. E. & Currie, P. J. External and internal structure of ankylosaur (Dinosauria, Ornithischia) osteoderms and their systematic relevance. J. Vertebr. Paleontol. 34, 835 - 851 (2014)." title="External and internal structure of ankylosaur (Dinosauria, Ornithischia) osteoderms and their systematic relevance" type="journal article" year="2014">25</bibRefCitation>
|
||
</superScript>
|
||
(
|
||
<figureCitation box="[538,611,318,340]" captionStart="Fig" captionStartId="1.[113,143,1216,1236]" captionTargetBox="[263,1349,141,1183]" captionTargetId="figure-377@1.[299,1295,598,1183]" captionTargetPageId="1" captionText="Fig. 1 | Morphology and histology of Spicomellus afer, NHMUK PV R37412. a–d, Photographs (a,b) and 3D model produced from XCT scanning (c,d) showing the specimen in anterior/posterior (a,c) and dorsal (b,d) views. Red lines on a and b indicate where the specimen was sectioned for histological analysis. Red colouration on c and d indicates a cement used to consolidate the specimen. e–g, Thin-section photographs of the rod: full section of the rod (e) (see Fig. 2a for larger version); histological section through the dorsal osteodermal part of the rod (f) showing structural fibre bundles in an orthogonal ‘plywood-like’ arrangement; histological section through the rib part of the rod (g) showing heavily remodelled cortical bone. Yellow box in e indicates the position of f, blue box indicates the position of g. h, Histological section from the sacral shield of NHMUK PV R9293, an indeterminate ankylosaur from the Lower Cretaceous Wealden Group of the UK showing fibre bundles arranged in a pattern similar to that of the osteoderm in Spicomellus (f). i, Histological section from the rib of NHMUK PV R36643, an unnamed ankylosaur from the Callovian Oxford Clay Formation of the UK showing well-vascularized, remodelled cortical bone similar to that of the rib section of Spicomellus (g)." figureDoi="http://doi.org/10.5281/zenodo.5842124" httpUri="https://zenodo.org/record/5842124/files/figure.png" pageId="3">Fig. 1h</figureCitation>
|
||
); in contrast, in stegosaurs, only the osteoderms of
|
||
<taxonomicName box="[482,596,346,367]" class="Reptilia" family="Stegosauridae" genus="Stegosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Ornithischia" pageId="3" phylum="Chordata" rank="genus">
|
||
<emphasis box="[482,596,346,367]" italics="true" pageId="3">Stegosaurus</emphasis>
|
||
</taxonomicName>
|
||
have been histologically investigated, and while these possess mineralized fibres around their bases
|
||
<bibRefCitation author="de Buffrenil, V. & Farlow, J. O. & de Ricqles, A." box="[307,321,401,413]" journalOrPublisher="Paleobiology" pageId="3" pagination="459 - 473" part="12" refId="ref5061" refString="10. de Buffrenil, V., Farlow, J. O. & de Ricqles, A. Growth and function of Stegosaurus plates: evidence from bone histology. Paleobiology 12, 459 - 473 (1986)." title="Growth and function of Stegosaurus plates: evidence from bone histology" type="journal article" year="1986">
|
||
<superScript attach="left" box="[307,321,401,413]" fontSize="5" pageId="3">10</superScript>
|
||
</bibRefCitation>
|
||
, they do not have a plywood-like arrangement
|
||
<bibRefCitation author="Scheyer, T. M. & Sander, P. M." box="[165,179,429,441]" journalOrPublisher="J. Vertebr. Paleontol." pageId="3" pagination="874 - 893" part="24" refId="ref5103" refString="11. Scheyer, T. M. & Sander, P. M. Histology of ankylosaur osteoderms: implications for systematics and function. J. Vertebr. Paleontol. 24, 874 - 893 (2004)." title="Histology of ankylosaur osteoderms: implications for systematics and function" type="journal article" year="2004">
|
||
<superScript attach="right" box="[165,179,429,441]" fontSize="5" pageId="3">11</superScript>
|
||
</bibRefCitation>
|
||
. Mineralized fibre bundles have been observed in the early-diverging armoured dinosaur
|
||
<taxonomicName box="[477,608,458,479]" class="Reptilia" family="Scelidosauridae" genus="Scelidosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Ornithischia" pageId="3" phylum="Chordata" rank="genus">
|
||
<emphasis box="[477,608,458,479]" italics="true" pageId="3">Scelidosaurus</emphasis>
|
||
</taxonomicName>
|
||
(which is either the sister taxon to Eurypoda
|
||
<bibRefCitation author="Maidment, S. C. R. & Raven, T. J. & Ouarhache, D. & Barrett, P. M." box="[390,397,485,497]" journalOrPublisher="Gondwana Res." pageId="3" pagination="82 - 97" part="77" refId="ref4800" refString="4. Maidment, S. C. R., Raven, T. J., Ouarhache, D. & Barrett, P. M. North Africa's first stegosaur: implications for Gondwanan thyreophoran dinosaur diversity. Gondwana Res. 77, 82 - 97 (2020)." title="North Africa's first stegosaur: implications for Gondwanan thyreophoran dinosaur diversity" type="journal article" year="2020">
|
||
<superScript attach="left" box="[390,397,485,497]" fontSize="5" pageId="3">4</superScript>
|
||
</bibRefCitation>
|
||
or to Ankylosauria
|
||
<bibRefCitation author="Norman, D. B." box="[587,601,485,497]" journalOrPublisher="Zoo. J. Linn. Soc." pageId="3" pagination="1 - 86" part="191" refId="ref5795" refString="26. Norman, D. B. Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoo. J. Linn. Soc. 191, 1 - 86 (2021)." title="Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships" type="journal article" year="2021">
|
||
<superScript attach="left" box="[587,601,485,497]" fontSize="5" pageId="3">26</superScript>
|
||
</bibRefCitation>
|
||
), but these do not have a plywood-like arrangement either
|
||
<superScript attach="right" box="[517,548,513,525]" fontSize="5" pageId="3">
|
||
<bibRefCitation author="Scheyer, T. M. & Sander, P. M." box="[517,531,513,525]" journalOrPublisher="J. Vertebr. Paleontol." pageId="3" pagination="874 - 893" part="24" refId="ref5103" refString="11. Scheyer, T. M. & Sander, P. M. Histology of ankylosaur osteoderms: implications for systematics and function. J. Vertebr. Paleontol. 24, 874 - 893 (2004)." title="Histology of ankylosaur osteoderms: implications for systematics and function" type="journal article" year="2004">11</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Barrett, P. M. & Clarke, J. B. & Brinkman, D. B. & Chapman, S. D. & Ensom, P. C." box="[534,548,513,525]" journalOrPublisher="Cretac. Res." pageId="3" pagination="279 - 295" part="23" refId="ref5673" refString="24. Barrett, P. M., Clarke, J. B., Brinkman, D. B., Chapman, S. D. & Ensom, P. C. Morphology, histology and identification of the ' granicones' from the Purbeck Limestone Formation (Lower Cretaceous: Berriasian) of Dorset, southern England. Cretac. Res. 23, 279 - 295 (2002)." title="Morphology, histology and identification of the ' granicones' from the Purbeck Limestone Formation (Lower Cretaceous: Berriasian) of Dorset, southern England" type="journal article" year="2002">24</bibRefCitation>
|
||
</superScript>
|
||
. It has been suggested that the osteoderms of
|
||
<taxonomicName box="[354,485,542,563]" class="Reptilia" family="Scelidosauridae" genus="Scelidosaurus" higherTaxonomySource="GBIF" kingdom="Animalia" order="Ornithischia" pageId="3" phylum="Chordata" rank="genus">
|
||
<emphasis box="[354,485,542,563]" italics="true" pageId="3">Scelidosaurus</emphasis>
|
||
</taxonomicName>
|
||
represent the plesiomorphic condition for Ankylosauria
|
||
<bibRefCitation author="Scheyer, T. M. & Sander, P. M." box="[388,402,569,581]" journalOrPublisher="J. Vertebr. Paleontol." pageId="3" pagination="874 - 893" part="24" refId="ref5103" refString="11. Scheyer, T. M. & Sander, P. M. Histology of ankylosaur osteoderms: implications for systematics and function. J. Vertebr. Paleontol. 24, 874 - 893 (2004)." title="Histology of ankylosaur osteoderms: implications for systematics and function" type="journal article" year="2004">
|
||
<superScript attach="left" box="[388,402,569,581]" fontSize="5" pageId="3">11</superScript>
|
||
</bibRefCitation>
|
||
, and that the unique possession of a plywood-like arrangement of structural fibres in the osteoderms of ankylosaurs indicates an increased contribution from the dense connective tissues of the stratum compactum during osteoderm skeletogenesis relative to that of other thyreophorans
|
||
<bibRefCitation author="Burns, M. E. & Currie, P. J." box="[645,659,681,693]" journalOrPublisher="J. Vertebr. Paleontol." pageId="3" pagination="835 - 851" part="34" refId="ref5748" refString="25. Burns, M. E. & Currie, P. J. External and internal structure of ankylosaur (Dinosauria, Ornithischia) osteoderms and their systematic relevance. J. Vertebr. Paleontol. 34, 835 - 851 (2014)." title="External and internal structure of ankylosaur (Dinosauria, Ornithischia) osteoderms and their systematic relevance" type="journal article" year="2014">
|
||
<superScript attach="left" box="[645,659,681,693]" fontSize="5" pageId="3">25</superScript>
|
||
</bibRefCitation>
|
||
. It is therefore most parsimonious to consider that the plywood-like arrangement of structural fibre bundles is a synapomorphy of Ankylosauria within Thyreophora based on the evidence currently available, a conclusion also reached by other authors
|
||
<superScript attach="left" box="[553,585,793,805]" fontSize="5" pageId="3">
|
||
<bibRefCitation author="Scheyer, T. M. & Sander, P. M." box="[553,567,793,805]" journalOrPublisher="J. Vertebr. Paleontol." pageId="3" pagination="874 - 893" part="24" refId="ref5103" refString="11. Scheyer, T. M. & Sander, P. M. Histology of ankylosaur osteoderms: implications for systematics and function. J. Vertebr. Paleontol. 24, 874 - 893 (2004)." title="Histology of ankylosaur osteoderms: implications for systematics and function" type="journal article" year="2004">11</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Burns, M. E. & Currie, P. J." box="[571,585,793,805]" journalOrPublisher="J. Vertebr. Paleontol." pageId="3" pagination="835 - 851" part="34" refId="ref5748" refString="25. Burns, M. E. & Currie, P. J. External and internal structure of ankylosaur (Dinosauria, Ornithischia) osteoderms and their systematic relevance. J. Vertebr. Paleontol. 34, 835 - 851 (2014)." title="External and internal structure of ankylosaur (Dinosauria, Ornithischia) osteoderms and their systematic relevance" type="journal article" year="2014">25</bibRefCitation>
|
||
</superScript>
|
||
. The plywood-like arrangement of structural fibres therefore supports referral of
|
||
<taxonomicName box="[718,777,822,843]" genus="Spicomellus" pageId="3" rank="species" species="afer">
|
||
<emphasis box="[718,777,822,843]" italics="true" pageId="3">S. afer</emphasis>
|
||
</taxonomicName>
|
||
to Ankylosauria
|
||
<superScript attach="left" box="[272,338,849,861]" fontSize="5" pageId="3">
|
||
<bibRefCitation author="Scheyer, T. M. & Sander, P. M." box="[272,286,849,861]" journalOrPublisher="J. Vertebr. Paleontol." pageId="3" pagination="874 - 893" part="24" refId="ref5103" refString="11. Scheyer, T. M. & Sander, P. M. Histology of ankylosaur osteoderms: implications for systematics and function. J. Vertebr. Paleontol. 24, 874 - 893 (2004)." title="Histology of ankylosaur osteoderms: implications for systematics and function" type="journal article" year="2004">11</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Main, R. P. & de Ricqles, A. & Horner, J. R. & Padian, K." box="[289,303,849,861]" journalOrPublisher="Paleobiology" pageId="3" pagination="291 - 314" part="31" refId="ref5409" refString="18. Main, R. P., de Ricqles, A., Horner, J. R. & Padian, K. The evolution and function of thyreophoran dinosaur scutes: implications for plate function in stegosaurs. Paleobiology 31, 291 - 314 (2005)." title="The evolution and function of thyreophoran dinosaur scutes: implications for plate function in stegosaurs" type="journal article" year="2005">18</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Barrett, P. M. & Clarke, J. B. & Brinkman, D. B. & Chapman, S. D. & Ensom, P. C." box="[307,321,849,861]" journalOrPublisher="Cretac. Res." pageId="3" pagination="279 - 295" part="23" refId="ref5673" refString="24. Barrett, P. M., Clarke, J. B., Brinkman, D. B., Chapman, S. D. & Ensom, P. C. Morphology, histology and identification of the ' granicones' from the Purbeck Limestone Formation (Lower Cretaceous: Berriasian) of Dorset, southern England. Cretac. Res. 23, 279 - 295 (2002)." title="Morphology, histology and identification of the ' granicones' from the Purbeck Limestone Formation (Lower Cretaceous: Berriasian) of Dorset, southern England" type="journal article" year="2002">24</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Burns, M. E. & Currie, P. J." box="[324,338,849,861]" journalOrPublisher="J. Vertebr. Paleontol." pageId="3" pagination="835 - 851" part="34" refId="ref5748" refString="25. Burns, M. E. & Currie, P. J. External and internal structure of ankylosaur (Dinosauria, Ornithischia) osteoderms and their systematic relevance. J. Vertebr. Paleontol. 34, 835 - 851 (2014)." title="External and internal structure of ankylosaur (Dinosauria, Ornithischia) osteoderms and their systematic relevance" type="journal article" year="2014">25</bibRefCitation>
|
||
</superScript>
|
||
.
|
||
</paragraph>
|
||
<paragraph blockId="3.[113,779,150,1320]" pageId="3">
|
||
This structural fibre arrangement is also known in other tetrapods, including turtles
|
||
<superScript attach="left" box="[343,375,905,917]" fontSize="5" pageId="3">
|
||
<bibRefCitation author="Barrett, P. M. & Clarke, J. B. & Brinkman, D. B. & Chapman, S. D. & Ensom, P. C." box="[343,357,905,917]" journalOrPublisher="Cretac. Res." pageId="3" pagination="279 - 295" part="23" refId="ref5673" refString="24. Barrett, P. M., Clarke, J. B., Brinkman, D. B., Chapman, S. D. & Ensom, P. C. Morphology, histology and identification of the ' granicones' from the Purbeck Limestone Formation (Lower Cretaceous: Berriasian) of Dorset, southern England. Cretac. Res. 23, 279 - 295 (2002)." title="Morphology, histology and identification of the ' granicones' from the Purbeck Limestone Formation (Lower Cretaceous: Berriasian) of Dorset, southern England" type="journal article" year="2002">24</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Scheyer, T. M. & Syromyatnikova, E. V. & Danilov, I. G." box="[361,375,905,917]" journalOrPublisher="Foss. Rec." pageId="3" pagination="69 - 85" part="20" refId="ref5841" refString="27. Scheyer, T. M., Syromyatnikova, E. V. & Danilov, I. G. Turtle shell bone and osteoderm histology of Mesozoic and Cenozoic stem-trionychian Adocidae and Nanhsiungchelyida (Crypodira: Adocusia) from Central Asia, Mongolia and North America. Foss. Rec. 20, 69 - 85 (2017)." title="Turtle shell bone and osteoderm histology of Mesozoic and Cenozoic stem-trionychian Adocidae and Nanhsiungchelyida (Crypodira: Adocusia) from Central Asia, Mongolia and North America" type="journal article" year="2017">27</bibRefCitation>
|
||
</superScript>
|
||
, aetosaurs
|
||
<bibRefCitation author="Cerda, I. A. & Desojo, J. B. & Scheyer, T. M." box="[482,496,905,917]" journalOrPublisher="Palaeontology" pageId="3" pagination="721 - 745" part="61" refId="ref5904" refString="28. Cerda, I. A., Desojo, J. B. & Scheyer, T. M. Novel data on aetosaur (Archosauria: Pseudosuchia) osteoderm microanatomy and histology: palaeobiological implications. Palaeontology 61, 721 - 745 (2018)." title="Novel data on aetosaur (Archosauria: Pseudosuchia) osteoderm microanatomy and histology: palaeobiological implications" type="journal article" year="2018">
|
||
<superScript attach="right" box="[482,496,905,917]" fontSize="5" pageId="3">28</superScript>
|
||
</bibRefCitation>
|
||
, phytosaurs
|
||
<superScript attach="left" box="[618,649,905,917]" fontSize="5" pageId="3">
|
||
<bibRefCitation author="D'Emic, M. D. & Wilson, J. A. & Chatterjee, S." box="[618,632,905,917]" journalOrPublisher="J. Vertebr. Paleontol." pageId="3" pagination="165 - 177" part="29" refId="ref5953" refString="29. D'Emic, M. D., Wilson, J. A. & Chatterjee, S. The titanosaur (Dinosauria: Sauropoda) osteoderm record: review and first definitive specimen from India. J. Vertebr. Paleontol. 29, 165 - 177 (2009)." title="The titanosaur (Dinosauria: Sauropoda) osteoderm record: review and first definitive specimen from India" type="journal article" year="2009">29</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Scheyer, T. M. & Desojo, J. B. & Cerda, I. A." box="[635,649,905,917]" journalOrPublisher="Anat. Rec." pageId="3" pagination="240 - 260" part="297" refId="ref6006" refString="30. Scheyer, T. M., Desojo, J. B. & Cerda, I. A. Bone histology of phytosaur, aetosaur, and other archosauriform osteoderms (Eureptilia, Archosauromorpha). Anat. Rec. 297, 240 - 260 (2014)." title="Bone histology of phytosaur, aetosaur, and other archosauriform osteoderms (Eureptilia, Archosauromorpha)" type="journal article" year="2014">30</bibRefCitation>
|
||
</superScript>
|
||
, and titanosaurian sauropods
|
||
<bibRefCitation author="Cerda, I. A. & Garcia, R. A. & Powell, J. E. & Lopez, O." box="[300,314,933,945]" journalOrPublisher="J. Vertebr. Paleontol." pageId="3" pagination="905791" part="35" refId="ref6058" refString="31. Cerda, I. A., Garcia, R. A., Powell, J. E. & Lopez, O. Morphology, microanatomy and histology of titanosaur (Dinosauria, Sauropoda) osteoderms from the Upper Cretaceous of Patagonia. J. Vertebr. Paleontol. 35, e 905791 (2015)." title="Morphology, microanatomy and histology of titanosaur (Dinosauria, Sauropoda) osteoderms from the Upper Cretaceous of Patagonia" type="journal article" year="2015">
|
||
<superScript attach="left" box="[300,314,933,945]" fontSize="5" pageId="3">31</superScript>
|
||
</bibRefCitation>
|
||
, but NHMUK PV R37412 can be excluded from referral to any of these groups on morphological and stratigraphic grounds. No known phytosaur osteoderms are spine-like
|
||
<bibRefCitation author="Stocker, M. R. & Butler, R. J." box="[758,772,989,1001]" editor="Nesbitt, S. J. & et al." journalOrPublisher="Geological Society, London" pageId="3" pagination="91 - 117" refId="ref6119" refString="32. Stocker, M. R. & Butler, R. J. in Anatomy, Phylogeny and Palaeobiology of Early Archosaurs and their Kin (eds Nesbitt, S. J. et al.) 91 - 117 (Geological Society, London, 2013)." type="book chapter" volumeTitle="Anatomy, Phylogeny and Palaeobiology of Early Archosaurs and their Kin" year="2013">
|
||
<superScript attach="left" box="[758,772,989,1001]" fontSize="5" pageId="3">32</superScript>
|
||
</bibRefCitation>
|
||
, but those of some aetosaurs are
|
||
<bibRefCitation author="Desojo, J. B. & et al." box="[438,452,1017,1029]" editor="Nesbitt, S. J. & et al." journalOrPublisher="Geological Society, London" pageId="3" pagination="203 - 239" refId="ref6170" refString="33. Desojo, J. B., et al. in Anatomy, Phylogeny and Palaeobiology of Early Archosaurs and their Kin (eds Nesbitt, S. J. et al.) 203 - 239 (Geological Society, London, 2013)." type="book chapter" volumeTitle="Anatomy, Phylogeny and Palaeobiology of Early Archosaurs and their Kin" year="2013">
|
||
<superScript attach="left" box="[438,452,1017,1029]" fontSize="5" pageId="3">33</superScript>
|
||
</bibRefCitation>
|
||
. However, both phytosaurs and aetosaurs went extinct before the end of the Triassic
|
||
<superScript attach="right" box="[633,664,1045,1057]" fontSize="5" pageId="3">
|
||
<bibRefCitation author="Scheyer, T. M. & Desojo, J. B. & Cerda, I. A." box="[633,647,1045,1057]" journalOrPublisher="Anat. Rec." pageId="3" pagination="240 - 260" part="297" refId="ref6006" refString="30. Scheyer, T. M., Desojo, J. B. & Cerda, I. A. Bone histology of phytosaur, aetosaur, and other archosauriform osteoderms (Eureptilia, Archosauromorpha). Anat. Rec. 297, 240 - 260 (2014)." title="Bone histology of phytosaur, aetosaur, and other archosauriform osteoderms (Eureptilia, Archosauromorpha)" type="journal article" year="2014">30</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Desojo, J. B. & et al." box="[650,664,1045,1057]" editor="Nesbitt, S. J. & et al." journalOrPublisher="Geological Society, London" pageId="3" pagination="203 - 239" refId="ref6170" refString="33. Desojo, J. B., et al. in Anatomy, Phylogeny and Palaeobiology of Early Archosaurs and their Kin (eds Nesbitt, S. J. et al.) 203 - 239 (Geological Society, London, 2013)." type="book chapter" volumeTitle="Anatomy, Phylogeny and Palaeobiology of Early Archosaurs and their Kin" year="2013">33</bibRefCitation>
|
||
</superScript>
|
||
, so referral to these groups would invoke an unprecedented 30–40 million-year ghost lineage in either case. A few turtles possess osteoderms
|
||
<bibRefCitation author="Barrett, P. M. & Clarke, J. B. & Brinkman, D. B. & Chapman, S. D. & Ensom, P. C." box="[758,772,1101,1113]" journalOrPublisher="Cretac. Res." pageId="3" pagination="279 - 295" part="23" refId="ref5673" refString="24. Barrett, P. M., Clarke, J. B., Brinkman, D. B., Chapman, S. D. & Ensom, P. C. Morphology, histology and identification of the ' granicones' from the Purbeck Limestone Formation (Lower Cretaceous: Berriasian) of Dorset, southern England. Cretac. Res. 23, 279 - 295 (2002)." title="Morphology, histology and identification of the ' granicones' from the Purbeck Limestone Formation (Lower Cretaceous: Berriasian) of Dorset, southern England" type="journal article" year="2002">
|
||
<superScript attach="left" box="[758,772,1101,1113]" fontSize="5" pageId="3">24</superScript>
|
||
</bibRefCitation>
|
||
, including conical spines
|
||
<bibRefCitation author="Gaffney, E. S." box="[356,370,1129,1141]" journalOrPublisher="Bull. Am. Mus. Nat. Hist." pageId="3" pagination="1 - 263" part="194" refId="ref6218" refString="34. Gaffney, E. S. The comparative osteology of the Triassic turtle Proganochelys. Bull. Am. Mus. Nat. Hist. 194, 1 - 263 (1990)." title="The comparative osteology of the Triassic turtle Proganochelys" type="journal article" year="1990">
|
||
<superScript attach="left" box="[356,370,1129,1141]" fontSize="5" pageId="3">34</superScript>
|
||
</bibRefCitation>
|
||
, but their osteoderms are much smaller than those of NHMUK PV R37412 and often have a characteristic pustulate surface texture. Titanosaurid sauropods lack spine-like osteoderms
|
||
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,
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|
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and the clade did not originate until the Cretaceous
|
||
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</bibRefCitation>
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||
, requiring a 23 million-year ghost lineage. By contrast, the armoured dinosaurs possessed a wide variety of plate- and spine-like osteoderms and originated in the Early Jurassic
|
||
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,
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<bibRefCitation author="Maidment, S. C. R. & Raven, T. J. & Ouarhache, D. & Barrett, P. M." box="[538,545,1297,1309]" journalOrPublisher="Gondwana Res." pageId="3" pagination="82 - 97" part="77" refId="ref4800" refString="4. Maidment, S. C. R., Raven, T. J., Ouarhache, D. & Barrett, P. M. North Africa's first stegosaur: implications for Gondwanan thyreophoran dinosaur diversity. Gondwana Res. 77, 82 - 97 (2020)." title="North Africa's first stegosaur: implications for Gondwanan thyreophoran dinosaur diversity" type="journal article" year="2020">4</bibRefCitation>
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.
|
||
</paragraph>
|
||
</subSubSection>
|
||
</treatment>
|
||
</document> |