455 lines
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455 lines
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<document ID-DOI="10.1038/s42003-023-04498-7" ID-GBIF-Dataset="2dcaf4a2-4980-4971-b951-db14a4483e25" ID-PMC="PMC9935847" ID-PubMed="36797304" ID-Zenodo-Dep="7664992" approvalRequired="4" approvalRequired_for_document="1" approvalRequired_for_taxonomicNames="2" approvalRequired_for_textStreams="1" checkinTime="1677071382952" checkinUser="valdenar" docAuthor="Chimento, Nicolás R., Agnolín, Federico L., Manabe, Makoto, Tsuihiji, Takanobu, Rich, Thomas H., Vickers-Rich, Patricia & Novas, Fernando E." docDate="2023" docId="12276C25FFA41A16FF5FF81B80FEF919" docLanguage="en" docName="CommunBiol.6.146.1-6.pdf" docOrigin="Communications Biology (146) 6" docSource="http://dx.doi.org/10.1038/s42003-023-04498-7" docTitle="Patagorhynchus pascuali Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas 2023, sp. nov." docType="treatment" docVersion="4" lastPageNumber="4" masterDocId="EE1E145DFFA51A15FFD1FF858337FFE9" masterDocTitle="First monotreme from the Late Cretaceous of South America" masterLastPageNumber="6" masterPageNumber="1" pageNumber="2" updateTime="1677075795349" updateUser="ExternalLinkService" zenodo-license-document="CC-BY-ND-4.0">
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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>First monotreme from the Late Cretaceous of South America</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>Chimento, Nicolás R.</mods:namePart>
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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>Agnolín, Federico L.</mods:namePart>
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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>Manabe, Makoto</mods:namePart>
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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>Tsuihiji, Takanobu</mods:namePart>
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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>Rich, Thomas H.</mods:namePart>
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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>Vickers-Rich, Patricia</mods:namePart>
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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>Novas, Fernando E.</mods:namePart>
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</mods:name>
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<mods:typeOfResource>text</mods:typeOfResource>
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<mods:relatedItem type="host">
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<mods:titleInfo>
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<mods:title>Communications Biology</mods:title>
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</mods:titleInfo>
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<mods:part>
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<mods:date>2023</mods:date>
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<mods:detail type="series">
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<mods:title>146</mods:title>
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</mods:detail>
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<mods:detail type="pubDate">
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<mods:number>2023-02-16</mods:number>
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</mods:detail>
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<mods:detail type="volume">
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<mods:number>6</mods:number>
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</mods:detail>
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<mods:extent unit="page">
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<mods:start>1</mods:start>
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<mods:end>6</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/s42003-023-04498-7</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/s42003-023-04498-7</mods:identifier>
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<mods:identifier type="GBIF-Dataset">2dcaf4a2-4980-4971-b951-db14a4483e25</mods:identifier>
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<mods:identifier type="PMC">PMC9935847</mods:identifier>
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<mods:identifier type="PubMed">36797304</mods:identifier>
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<mods:identifier type="Zenodo-Dep">7664992</mods:identifier>
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</mods:mods>
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<treatment ID-DOI="http://doi.org/10.5281/zenodo.7665020" ID-GBIF-Taxon="209339374" ID-Zenodo-Dep="7665020" LSID="urn:lsid:plazi:treatment:12276C25FFA41A16FF5FF81B80FEF919" httpUri="http://treatment.plazi.org/id/12276C25FFA41A16FF5FF81B80FEF919" lastPageId="3" lastPageNumber="4" pageId="1" pageNumber="2">
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<subSubSection box="[142,479,1950,1971]" pageId="1" pageNumber="2" type="nomenclature">
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<paragraph blockId="1.[116,779,1894,1971]" box="[142,479,1950,1971]" pageId="1" pageNumber="2">
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<heading box="[142,479,1950,1971]" fontSize="9" level="2" pageId="1" pageNumber="2" reason="1">
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<taxonomicName authority="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas, 2023" authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" box="[142,390,1950,1971]" genus="Patagorhynchus" kingdom="Animalia" order="Monotremata" pageId="1" pageNumber="2" rank="species" species="pascuali" status="sp. nov.">
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<emphasis box="[142,390,1950,1971]" italics="true" pageId="1" pageNumber="2">Patagorhynchus pascuali</emphasis>
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</taxonomicName>
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<taxonomicNameLabel box="[399,479,1950,1971]" pageId="1" pageNumber="2" rank="species">sp. nov.</taxonomicNameLabel>
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</heading>
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</paragraph>
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</subSubSection>
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<footnote box="[677,1378,2007,2023]" pageId="1" pageNumber="2">
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<paragraph blockId="1.[677,1378,2007,2023]" box="[677,1378,2007,2023]" pageId="1" pageNumber="2">(2023) 6:146 | https://doi.org/10.1038/s42003-023-04498-7 | www.nature.com/commsbio</paragraph>
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</footnote>
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<subSubSection pageId="2" pageNumber="3" type="etymology">
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<paragraph blockId="2.[116,778,136,242]" pageId="2" pageNumber="3">
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<emphasis bold="true" box="[116,228,136,157]" pageId="2" pageNumber="3">Etymology</emphasis>
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. Species name honors the Argentine paleomammalogist Rosendo Pascual (1923–2012), who described the first Cenozoic monotreme remains from Patagonia, thus demonstrating the presence of this clade outside Australia.
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</paragraph>
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</subSubSection>
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<subSubSection pageId="2" pageNumber="3" type="materials_examined">
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<paragraph blockId="2.[116,778,283,389]" pageId="2" pageNumber="3">
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<materialsCitation ID-GBIF-Occurrence="4035843301" collectingDate="2022-03" collectorName="N. R. Chimento" country="Argentina" location="Rio Gallegos" pageId="2" pageNumber="3" specimenCode="MPM-PV-23087" specimenCount="1" stateProvince="Santa Cruz" typeStatus="holotype">
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<emphasis bold="true" box="[116,213,283,304]" pageId="2" pageNumber="3">
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<typeStatus box="[116,213,283,304]" pageId="2" pageNumber="3">Holotype</typeStatus>
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</emphasis>
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.
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<specimenCode box="[228,398,283,304]" pageId="2" pageNumber="3">MPM-PV-23087</specimenCode>
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, Museo Padre Molina (
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<location LSID="urn:lsid:plazi:treatment:12276C25FFA41A16FF5FF81B80FEF919:9F518BE8FFA71A17FD53FE9E8031FED8" box="[642,774,283,305]" country="Argentina" name="Rio Gallegos" pageId="2" pageNumber="3" stateProvince="Santa Cruz">Rio Gallegos</location>
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,
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<collectingRegion box="[116,230,311,332]" country="Argentina" name="Santa Cruz" pageId="2" pageNumber="3">Santa Cruz</collectingRegion>
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,
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<collectingCountry box="[242,347,311,333]" name="Argentina" pageId="2" pageNumber="3">Argentina</collectingCountry>
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), a right lower m2 attached to a fragment of dentary. Collected by
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<collectorName box="[361,519,339,361]" pageId="2" pageNumber="3">N. R. Chimento</collectorName>
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during a joint ArgentineJapanese field trip in
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<date box="[337,463,367,389]" pageId="2" pageNumber="3" value="2022-03">
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<collectingDate box="[337,463,367,389]" pageId="2" pageNumber="3" value="2022-03">March 2022</collectingDate>
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</date>
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.
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</materialsCitation>
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</paragraph>
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</subSubSection>
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<subSubSection box="[116,617,429,451]" pageId="2" pageNumber="3" type="diagnosis">
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<paragraph blockId="2.[116,617,429,451]" box="[116,617,429,451]" pageId="2" pageNumber="3">
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<emphasis bold="true" box="[116,220,429,451]" pageId="2" pageNumber="3">Diagnosis</emphasis>
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. The same as for genus by monotypy.
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</paragraph>
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</subSubSection>
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<subSubSection pageId="2" pageNumber="3" type="materials_examined">
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<paragraph blockId="2.[116,778,492,709]" pageId="2" pageNumber="3">
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<emphasis bold="true" box="[116,359,492,514]" pageId="2" pageNumber="3">Type locality and age</emphasis>
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. La Anita farm, Santa Cruz Province, Patagonia, Argentina. The tooth was collected from the “Puma Cave” fossil site (S 50 30.639 W 72 33.617), Chorrillo Formation, early Maastrichtian7,8. This new discovery expands the list of Late Cretaceous mammaliaforms recorded in the Chorrillo Formation and equivalent Dorotea Formation in southern Chile, previously known to include gondwanatherians (
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<taxonomicName authorityName="Goin, Martinelli, Soto-Acuña, Vieytes, Leslie, Fernández, Pino, Trevisan, Kaluza, Reguero, Leppe, Ortíz, Rubilar-Rogers & Vargas" authorityYear="2020" box="[512,657,659,680]" class="Mammalia" genus="Magallanodon" higherTaxonomySource="GBIF" kingdom="Animalia" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
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<emphasis box="[512,657,659,680]" italics="true" pageId="2" pageNumber="3">Magallanodon</emphasis>
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</taxonomicName>
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) and dryolestoids (
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<taxonomicName box="[208,334,687,708]" class="Mammalia" family="Mesungulatidae" genus="Orretherium" higherTaxonomySource="GBIF" kingdom="Animalia" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
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<emphasis box="[208,334,687,708]" italics="true" pageId="2" pageNumber="3">Orretherium</emphasis>
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</taxonomicName>
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)9–11,13.
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</paragraph>
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</subSubSection>
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<subSubSection pageId="2" pageNumber="3" type="description">
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<paragraph blockId="2.[116,778,750,1972]" pageId="2" pageNumber="3">
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<emphasis bold="true" box="[116,240,750,772]" pageId="2" pageNumber="3">Description</emphasis>
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. Despite the occlusal surface being somewhat damaged, the morphology of the main cusps and anatomical details can be clearly discerned. The tooth is identified as a second lower molar based on the similarities with the m2 of
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<taxonomicName authorityName="Woodburne & Tedford" authorityYear="1975" box="[658,773,834,855]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
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<emphasis box="[658,773,834,855]" italics="true" pageId="2" pageNumber="3">Obdurodon</emphasis>
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</taxonomicName>
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, including a subrectangular-shaped outline in occlusal view, the presence of two lobes each bearing three cusps, a mid-valley lacking cusps, and prominent anterior and posterior cingulids (
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<figureCitation box="[123,183,945,967]" captionStart="Fig" captionStartId="1.[810,840,876,896]" captionTargetBox="[820,1460,135,853]" captionTargetId="figure-526@1.[820,1460,135,853]" captionTargetPageId="1" captionText="Fig. 1 Images of Patagorhynchus pascuali, MPM-PV-23087. Lower molar 2 and part of the right jaw, in a, occlusal view; b, medial/lingual view; c, lateral/labial view; d, posterior view; e, anterior view. Scale bar: length 2 mm. Abbreviations, ac, anterior cingulid; alv, alveolus; ant, anterior; ar, anterior root; hy, hypoconid; hl, hypoconulid; lapcc, labial posterior cingular cusp; liacc, lingual anterior cingular cusp; me, metaconid; mv, mid-valley; NC1, neomorphic cusp 1; pa, paraconid; pc, posterior cingulid; pr, protoconid; prt, posterior root." figureDoi="http://doi.org/10.5281/zenodo.7664994" httpUri="https://zenodo.org/record/7664994/files/figure.png" pageId="2" pageNumber="3">Fig. 1</figureCitation>
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). Immediately anterior to m2, the fragmentary mandible shows a partially preserved and relatively small alveolus on the labial margin, which presumably corresponds to one of the roots of m1.
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</paragraph>
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<paragraph blockId="2.[116,778,750,1972]" pageId="2" pageNumber="3">
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The
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<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" box="[192,351,1057,1078]" genus="Patagorhynchus" pageId="2" pageNumber="3" rank="genus">
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<emphasis box="[192,351,1057,1078]" italics="true" pageId="2" pageNumber="3">Patagorhynchus</emphasis>
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</taxonomicName>
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m2 exhibits a distinct morphology that easily identifies it as a monotreme. This includes a unique lophid and cusp structure resulting in the presence of two mesiodistally compressed lobes that are sub-equally in shaped and size each consisting of three cusps, twinned paraconid and metaconid, wrapping cingulid, hypsodont lobes, and un-basined talonid12,14,15.
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</paragraph>
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<paragraph blockId="2.[116,778,750,1972]" pageId="2" pageNumber="3">
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The m2 is 5.8 mm in mesiodistal length (see Supplementary Results 3), indicating that this tooth of
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<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" box="[569,725,1280,1301]" genus="Patagorhynchus" pageId="2" pageNumber="3" rank="genus">
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<emphasis box="[569,725,1280,1301]" italics="true" pageId="2" pageNumber="3">Patagorhynchus</emphasis>
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</taxonomicName>
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was possibly intermediate in size between
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<taxonomicName box="[511,667,1309,1330]" class="Mammalia" family="Ornithorhynchidae" genus="Monotrematum" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
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<emphasis box="[511,667,1309,1330]" italics="true" pageId="2" pageNumber="3">Monotrematum</emphasis>
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</taxonomicName>
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and some species of
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<taxonomicName authorityName="Woodburne & Tedford" authorityYear="1975" box="[237,349,1336,1357]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
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<emphasis box="[237,349,1336,1357]" italics="true" pageId="2" pageNumber="3">Obdurodon</emphasis>
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</taxonomicName>
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. The m2 is mesiodistally longer than transversely wide, and narrows mesially. Six large cusps are present: protoconid, paraconid, metaconid, hypoconid, hypoconulid, and NC1 (neomorphic cuspid 1)16. These cusps are relatively low and mound-like and connected by lophids, which form two main lobes or triakididrepanids (
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<figureCitation box="[447,505,1475,1497]" captionStart="Fig" captionStartId="1.[810,840,876,896]" captionTargetBox="[820,1460,135,853]" captionTargetId="figure-526@1.[820,1460,135,853]" captionTargetPageId="1" captionText="Fig. 1 Images of Patagorhynchus pascuali, MPM-PV-23087. Lower molar 2 and part of the right jaw, in a, occlusal view; b, medial/lingual view; c, lateral/labial view; d, posterior view; e, anterior view. Scale bar: length 2 mm. Abbreviations, ac, anterior cingulid; alv, alveolus; ant, anterior; ar, anterior root; hy, hypoconid; hl, hypoconulid; lapcc, labial posterior cingular cusp; liacc, lingual anterior cingular cusp; me, metaconid; mv, mid-valley; NC1, neomorphic cusp 1; pa, paraconid; pc, posterior cingulid; pr, protoconid; prt, posterior root." figureDoi="http://doi.org/10.5281/zenodo.7664994" httpUri="https://zenodo.org/record/7664994/files/figure.png" pageId="2" pageNumber="3">Fig. 1</figureCitation>
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, Supplementary
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<figureCitation box="[676,734,1475,1497]" captionStart="Fig" captionStartId="1.[810,840,1839,1859]" captionTargetBox="[821,1459,1227,1815]" captionTargetId="figure-614@1.[820,1460,1225,1816]" captionTargetPageId="1" captionText="Fig. 2 Comparisons of the second lower molar of selected monotremaformes in occlusal view. a, Patagorhynchus pascuali (based in MPM-PV-23087); b, Obdurodon insignis2,19; c, Monotrematum sudamericanum17; d, Teinolophus trusleri20. Not to scale. Abbreviations: NC1, neoformation cusp 1." figureDoi="http://doi.org/10.5281/zenodo.7664996" httpUri="https://zenodo.org/record/7664996/files/figure.png" pageId="2" pageNumber="3">Fig. 2</figureCitation>
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).
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</paragraph>
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<paragraph blockId="2.[116,778,750,1972]" pageId="2" pageNumber="3">
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The anterior lobe (equivalent to trigonid) is labiolingually narrower and apicobasally taller than the posterior lobe (equivalent to a talonid), a condition shared with
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<taxonomicName authorityName="Woodburne & Tedford" authorityYear="1975" box="[516,627,1559,1580]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[516,627,1559,1580]" italics="true" pageId="2" pageNumber="3">Obdurodon</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
12. In
|
|||
|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" genus="Patagorhynchus" pageId="2" pageNumber="3" rank="genus">
|
|||
|
|
<emphasis italics="true" pageId="2" pageNumber="3">Patagorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
, the anterior lobe is heart-shaped, with the anterior and posterior lophids being slightly convex posteriorly. This results in the paraconids being located anteriorly at the same level as the protoconid. In
|
|||
|
|
<taxonomicName authorityName="Woodburne & Tedford" authorityYear="1975" box="[280,391,1671,1692]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[280,391,1671,1692]" italics="true" pageId="2" pageNumber="3">Obdurodon</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
, by contrast, the anterior lophid is anteriorly convex and the posterior one is straight, resulting in metaconid and protoconid being located at the same level. In
|
|||
|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" box="[116,270,1754,1775]" genus="Patagorhynchus" pageId="2" pageNumber="3" rank="genus">
|
|||
|
|
<emphasis box="[116,270,1754,1775]" italics="true" pageId="2" pageNumber="3">Patagorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
, the paraconid is larger than the metaconid, and its base is ventrally positioned relative to the base of both the metaconid and protoconid, suggesting that the paraconid was more ventrally located than the other cusps.
|
|||
|
|
</paragraph>
|
|||
|
|
<paragraph blockId="2.[116,778,750,1972]" lastBlockId="2.[810,1472,136,1023]" pageId="2" pageNumber="3">The posterior (talonid) lobe is similar in shape to the anterior (trigonid) lobe, but much wider labiolingually. The lingual cusps are notably taller than the labial one (hypoconid). The preserved bases of the NC1 and hypoconulid are subequal in size and position. The hypoconid is mesiodistally narrower than the protoconid.</paragraph>
|
|||
|
|
<paragraph blockId="2.[810,1472,136,1023]" pageId="2" pageNumber="3">
|
|||
|
|
Between the lingual cusps of paired lobes there is a narrow, eye-shaped enamel invagination, reminiscent of a flexid. Such a condition is also present in
|
|||
|
|
<taxonomicName box="[1111,1270,249,270]" class="Mammalia" family="Ornithorhynchidae" genus="Monotrematum" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1111,1270,249,270]" italics="true" pageId="2" pageNumber="3">Monotrematum</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
17 and some specimens of
|
|||
|
|
<taxonomicName authorityName="Woodburne & Tedford" authorityYear="1975" box="[896,1011,276,297]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[896,1011,276,297]" italics="true" pageId="2" pageNumber="3">Obdurodon</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
18.
|
|||
|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" box="[1042,1201,276,297]" genus="Patagorhynchus" pageId="2" pageNumber="3" rank="genus">
|
|||
|
|
<emphasis box="[1042,1201,276,297]" italics="true" pageId="2" pageNumber="3">Patagorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
resembles
|
|||
|
|
<taxonomicName box="[1312,1471,277,298]" class="Mammalia" family="Ornithorhynchidae" genus="Monotrematum" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1312,1471,277,298]" italics="true" pageId="2" pageNumber="3">Monotrematum</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
in that the invaginations are delimited by a narrow enamel layer (
|
|||
|
|
<figureCitation box="[817,874,332,354]" captionStart="Fig" captionStartId="1.[810,840,1839,1859]" captionTargetBox="[821,1459,1227,1815]" captionTargetId="figure-614@1.[820,1460,1225,1816]" captionTargetPageId="1" captionText="Fig. 2 Comparisons of the second lower molar of selected monotremaformes in occlusal view. a, Patagorhynchus pascuali (based in MPM-PV-23087); b, Obdurodon insignis2,19; c, Monotrematum sudamericanum17; d, Teinolophus trusleri20. Not to scale. Abbreviations: NC1, neoformation cusp 1." figureDoi="http://doi.org/10.5281/zenodo.7664996" httpUri="https://zenodo.org/record/7664996/files/figure.png" pageId="2" pageNumber="3">Fig. 2</figureCitation>
|
|||
|
|
, Supplementary
|
|||
|
|
<figureCitation box="[1045,1102,332,354]" captionStart="Fig" captionStartId="1.[810,840,1839,1859]" captionTargetBox="[821,1459,1227,1815]" captionTargetId="figure-614@1.[820,1460,1225,1816]" captionTargetPageId="1" captionText="Fig. 2 Comparisons of the second lower molar of selected monotremaformes in occlusal view. a, Patagorhynchus pascuali (based in MPM-PV-23087); b, Obdurodon insignis2,19; c, Monotrematum sudamericanum17; d, Teinolophus trusleri20. Not to scale. Abbreviations: NC1, neoformation cusp 1." figureDoi="http://doi.org/10.5281/zenodo.7664996" httpUri="https://zenodo.org/record/7664996/files/figure.png" pageId="2" pageNumber="3">Fig. 2</figureCitation>
|
|||
|
|
), in contrast to
|
|||
|
|
<taxonomicName authorityName="Woodburne & Tedford" authorityYear="1975" box="[1262,1377,332,353]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1262,1377,332,353]" italics="true" pageId="2" pageNumber="3">Obdurodon</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
in which the invaginations are labiolingually extended19.
|
|||
|
|
</paragraph>
|
|||
|
|
<paragraph blockId="2.[810,1472,136,1023]" pageId="2" pageNumber="3">Both lobes are separated by a wide, deep mid-valley, which extends from the labial through the lingual edges of the tooth. The margins of the valley widen slightly towards the labial edge of the tooth. The valley lacks well-defined cusps or fossettes, and becomes deeper towards its labial margin.</paragraph>
|
|||
|
|
<paragraph blockId="2.[810,1472,136,1023]" pageId="2" pageNumber="3">
|
|||
|
|
Posterior and anterior cingulids are prominent, being wider than those in
|
|||
|
|
<taxonomicName authorityName="Rich, Vickers-Rich, Constantine, Flannery, Kool & van Klaveren" authorityYear="1999" box="[995,1115,555,576]" class="Mammalia" family="Teinolophidae" genus="Teinolophos" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[995,1115,555,576]" italics="true" pageId="2" pageNumber="3">Teinolophos</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
but narrower than those in
|
|||
|
|
<taxonomicName authorityName="Woodburne & Tedford" authorityYear="1975" box="[810,925,583,604]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[810,925,583,604]" italics="true" pageId="2" pageNumber="3">Obdurodon</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
16,20. The posterior cingulum is eroded on its lingual end, but the preserved segment maintains a constant width along its length, being similar in this morphology to that in
|
|||
|
|
<taxonomicName authorityName="Woodburne & Tedford" authorityYear="1975" box="[1351,1466,639,660]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1351,1466,639,660]" italics="true" pageId="2" pageNumber="3">Obdurodon</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
. In contrast, the cingulids become lingually wider in
|
|||
|
|
<taxonomicName authorityName="Rich, Vickers-Rich, Constantine, Flannery, Kool & van Klaveren" authorityYear="1999" box="[810,930,694,715]" class="Mammalia" family="Teinolophidae" genus="Teinolophos" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[810,930,694,715]" italics="true" pageId="2" pageNumber="3">Teinolophos</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
20. The anterior cingulid hosts a small cusp on its lingual end, whereas in the posterior cingulid the labial end shows a cusp (the lingual end of this cingulid is eroded, precluding the recognition of cusps), similar to the morphology in
|
|||
|
|
<taxonomicName class="Mammalia" family="Ornithorhynchidae" genus="Monotrematum" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis italics="true" pageId="2" pageNumber="3">Monotrematum</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
, but differing from that in
|
|||
|
|
<taxonomicName authorityName="Woodburne & Tedford" authorityYear="1975" box="[1123,1238,806,827]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1123,1238,806,827]" italics="true" pageId="2" pageNumber="3">Obdurodon</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
(
|
|||
|
|
<figureCitation box="[1250,1307,806,828]" captionStart="Fig" captionStartId="1.[810,840,1839,1859]" captionTargetBox="[821,1459,1227,1815]" captionTargetId="figure-614@1.[820,1460,1225,1816]" captionTargetPageId="1" captionText="Fig. 2 Comparisons of the second lower molar of selected monotremaformes in occlusal view. a, Patagorhynchus pascuali (based in MPM-PV-23087); b, Obdurodon insignis2,19; c, Monotrematum sudamericanum17; d, Teinolophus trusleri20. Not to scale. Abbreviations: NC1, neoformation cusp 1." figureDoi="http://doi.org/10.5281/zenodo.7664996" httpUri="https://zenodo.org/record/7664996/files/figure.png" pageId="2" pageNumber="3">Fig. 2</figureCitation>
|
|||
|
|
, Supplementary
|
|||
|
|
<figureCitation box="[810,869,834,856]" captionStart="Fig" captionStartId="1.[810,840,1839,1859]" captionTargetBox="[821,1459,1227,1815]" captionTargetId="figure-614@1.[820,1460,1225,1816]" captionTargetPageId="1" captionText="Fig. 2 Comparisons of the second lower molar of selected monotremaformes in occlusal view. a, Patagorhynchus pascuali (based in MPM-PV-23087); b, Obdurodon insignis2,19; c, Monotrematum sudamericanum17; d, Teinolophus trusleri20. Not to scale. Abbreviations: NC1, neoformation cusp 1." figureDoi="http://doi.org/10.5281/zenodo.7664996" httpUri="https://zenodo.org/record/7664996/files/figure.png" pageId="2" pageNumber="3">Fig. 2</figureCitation>
|
|||
|
|
).
|
|||
|
|
</paragraph>
|
|||
|
|
<paragraph blockId="2.[810,1472,136,1023]" pageId="2" pageNumber="3">
|
|||
|
|
The tooth bears two roots that are broad labiolingually and constricted at mid-height; they are obliquely oriented with respect to the main axis of the tooth. Regarding the root number,
|
|||
|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" box="[810,969,945,966]" genus="Patagorhynchus" pageId="2" pageNumber="3" rank="genus">
|
|||
|
|
<emphasis box="[810,969,945,966]" italics="true" pageId="2" pageNumber="3">Patagorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
retains the ancestral condition in m2 shared with
|
|||
|
|
<taxonomicName authorityName="Rich, Vickers-Rich, Constantine, Flannery, Kool & van Klaveren" authorityYear="1999" box="[810,930,973,994]" class="Mammalia" family="Teinolophidae" genus="Teinolophos" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[810,930,973,994]" italics="true" pageId="2" pageNumber="3">Teinolophos</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
(and probably
|
|||
|
|
<taxonomicName box="[1098,1257,974,995]" class="Mammalia" family="Ornithorhynchidae" genus="Monotrematum" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1098,1257,974,995]" italics="true" pageId="2" pageNumber="3">Monotrematum</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
), differing from the multiple roots present in
|
|||
|
|
<taxonomicName authorityName="Woodburne & Tedford" authorityYear="1975" box="[1073,1188,1001,1022]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1073,1188,1001,1022]" italics="true" pageId="2" pageNumber="3">Obdurodon</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
and
|
|||
|
|
<taxonomicName box="[1242,1412,1001,1022]" class="Mammalia" family="Ornithorhynchidae" genus="Ornithorhynchus" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1242,1412,1001,1022]" italics="true" pageId="2" pageNumber="3">Ornithorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
16,20.
|
|||
|
|
</paragraph>
|
|||
|
|
</subSubSection>
|
|||
|
|
<subSubSection lastPageId="3" lastPageNumber="4" pageId="2" pageNumber="3" type="discussion">
|
|||
|
|
<paragraph blockId="2.[810,1472,1084,1972]" box="[810,927,1084,1107]" pageId="2" pageNumber="3">
|
|||
|
|
<heading bold="true" box="[810,927,1084,1107]" fontSize="9" level="1" pageId="2" pageNumber="3" reason="0">
|
|||
|
|
<emphasis bold="true" box="[810,927,1084,1107]" pageId="2" pageNumber="3">Discussion</emphasis>
|
|||
|
|
</heading>
|
|||
|
|
</paragraph>
|
|||
|
|
<paragraph blockId="2.[810,1472,1084,1972]" pageId="2" pageNumber="3">
|
|||
|
|
As indicated above, the crown shape of
|
|||
|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" box="[1235,1394,1113,1134]" genus="Patagorhynchus" pageId="2" pageNumber="3" rank="genus">
|
|||
|
|
<emphasis box="[1235,1394,1113,1134]" italics="true" pageId="2" pageNumber="3">Patagorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
unambiguously indicates that this taxon belongs to monotremes. With the aim to test the phylogenetic position of
|
|||
|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" box="[1270,1429,1169,1190]" genus="Patagorhynchus" pageId="2" pageNumber="3" rank="genus">
|
|||
|
|
<emphasis box="[1270,1429,1169,1190]" italics="true" pageId="2" pageNumber="3">Patagorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
, we scored this tooth into a previously published data matrix composed by 558 characters and 128 taxa21 (see Supplementary Methods 1 and 2). We concentrated on the characters available in this new tooth, a total of 54 characters can be scored for
|
|||
|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" genus="Patagorhynchus" pageId="2" pageNumber="3" rank="genus">
|
|||
|
|
<emphasis italics="true" pageId="2" pageNumber="3">Patagorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
(Supplementary Results 1 and 2). The results of the phylogenetic analysis consistently place
|
|||
|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" box="[1214,1373,1336,1357]" genus="Patagorhynchus" pageId="2" pageNumber="3" rank="genus">
|
|||
|
|
<emphasis box="[1214,1373,1336,1357]" italics="true" pageId="2" pageNumber="3">Patagorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
as nested within monotremes, together with the genera
|
|||
|
|
<emphasis italics="true" pageId="2" pageNumber="3">
|
|||
|
|
<taxonomicName authority=", Tachyglossus" authorityName="Tachyglossus" class="Mammalia" family="Ornithorhynchidae" genus="Ornithorhynchus" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">Ornithorhynchus, Tachyglossus</taxonomicName>
|
|||
|
|
,
|
|||
|
|
<taxonomicName box="[956,1115,1392,1413]" class="Mammalia" family="Ornithorhynchidae" genus="Monotrematum" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">Monotrematum</taxonomicName>
|
|||
|
|
</emphasis>
|
|||
|
|
and
|
|||
|
|
<taxonomicName authorityName="Woodburne & Tedford" authorityYear="1975" box="[1178,1293,1392,1413]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1178,1293,1392,1413]" italics="true" pageId="2" pageNumber="3">Obdurodon</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
(
|
|||
|
|
<figureCitation box="[1312,1376,1392,1414]" captionStart="Fig" captionStartId="3.[116,146,1112,1132]" captionTargetBox="[127,766,136,1087]" captionTargetId="figure-766@3.[127,767,135,1088]" captionTargetPageId="3" captionText="Fig. 3 Simplified calibrated cladogram showing the phylogenetic affinities of Patagorhynchus pascuali. Basal Monotremaformes44 are indicated in red and Monotremata in green. The Late Cretaceous (Maastrichtian) palaeogeographical map (based in Scotese35) indicates the fossiliferous sites that yielded fossil toothed monotremes and distribution of the extant platypus Ornithorhynchus anatinus shaded in light brown. [1], occurrence of Patagorhynchus pascuali, La Anita farm, Chorrillo Formation (Maastrichtian, Late Cretaceous); [2], occurrence of Monotrematum sudamericanum, Punta Peligro locality, Salamanca Formation (Danian, lower Paleocene); [3], occurrence of Obdurodon spp., different localities from South Australia, Queensland, and New South Wales Oligocene-Pliocene); [4], Pleistocene occurrences and geographic distribution of extant Ornithorhynchus anatinus." figureDoi="http://doi.org/10.5281/zenodo.7664998" httpUri="https://zenodo.org/record/7664998/files/figure.png" pageId="2" pageNumber="3">Fig. 3</figureCitation>
|
|||
|
|
, Supplementary
|
|||
|
|
<figureCitation box="[902,958,1420,1442]" captionStart="Fig" captionStartId="1.[810,840,876,896]" captionTargetBox="[820,1460,135,853]" captionTargetId="figure-526@1.[820,1460,135,853]" captionTargetPageId="1" captionText="Fig. 1 Images of Patagorhynchus pascuali, MPM-PV-23087. Lower molar 2 and part of the right jaw, in a, occlusal view; b, medial/lingual view; c, lateral/labial view; d, posterior view; e, anterior view. Scale bar: length 2 mm. Abbreviations, ac, anterior cingulid; alv, alveolus; ant, anterior; ar, anterior root; hy, hypoconid; hl, hypoconulid; lapcc, labial posterior cingular cusp; liacc, lingual anterior cingular cusp; me, metaconid; mv, mid-valley; NC1, neomorphic cusp 1; pa, paraconid; pc, posterior cingulid; pr, protoconid; prt, posterior root." figureDoi="http://doi.org/10.5281/zenodo.7664994" httpUri="https://zenodo.org/record/7664994/files/figure.png" pageId="2" pageNumber="3">Fig. 1</figureCitation>
|
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).
|
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</paragraph>
|
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<paragraph blockId="2.[810,1472,1084,1972]" pageId="2" pageNumber="3">
|
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|
|
Australia has yielded the most complete fossil record of monotremes2, including an array of Barremian through Cenomanian taxa, as well as several species of the Oligocene-Pliocene monotreme
|
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|
|
<taxonomicName authorityName="Woodburne & Tedford" authorityYear="1975" box="[942,1057,1531,1552]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
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|
|
<emphasis box="[942,1057,1531,1552]" italics="true" pageId="2" pageNumber="3">Obdurodon</emphasis>
|
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</taxonomicName>
|
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|
|
. In this context, the presence of the toothed monotreme
|
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|
|
<taxonomicName box="[1030,1189,1560,1581]" class="Mammalia" family="Ornithorhynchidae" genus="Monotrematum" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="genus">
|
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<emphasis box="[1030,1189,1560,1581]" italics="true" pageId="2" pageNumber="3">Monotrematum</emphasis>
|
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</taxonomicName>
|
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|
|
in the early Paleocene of Patagonia1,22 was interpreted as the result of a single dispersal of monotremes from Australia to South America, before or during the Late Cretaceous or early Paleocene2–6. Discovery of
|
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|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" genus="Patagorhynchus" pageId="2" pageNumber="3" rank="genus">
|
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<emphasis italics="true" pageId="2" pageNumber="3">Patagorhynchus</emphasis>
|
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</taxonomicName>
|
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|
|
clearly demonstrates that the monotremes had already attained a wide paleogeographic distribution, stretching across southern South America, Australia, and Antarctica, the later one as a connecting pathway (but fossil monotremes are still unknown from this landmass), constituting a clade characteristic of the Weddelian Paleobiogeographical Province23–28.
|
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</paragraph>
|
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<paragraph blockId="2.[810,1472,1084,1972]" lastBlockId="3.[810,1472,136,1776]" lastPageId="3" lastPageNumber="4" pageId="2" pageNumber="3">
|
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|
The new discovery expands the list of mammals documented in the Chorrillo and equivalent Dorotea formations of southern South America, adding the
|
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|
<taxonomicName authorityName=", Bonaparte" authorityYear="1837" box="[1104,1243,1894,1915]" class="Mammalia" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="2" pageNumber="3" phylum="Chordata" rank="order">Monotremata</taxonomicName>
|
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to the assemblage of non-therian mammals (i.e., gondwanatherians and meridiolestidan dryolestoids9–11,13). Remarkably, monotremes are absent from the extensively sampled Late Cretaceous localities of northern and central Patagonia2,29,30. Such a difference among mammalian assemblages characteristic of Patagonia is consistent with the uneven distribution of non-avian dinosaurs in this region. For example, megaraptorid theropods, colossosaurian titanosaurs, and elasmarian iguanodontians are numerically dominant in the Chorrillo Formation8,31 whereas abelisaurid theropods and saltasaurine titanosaurs are prevalent in coeval units in northern Patagonia. Similar differences are documented in terrestrial and marine biotas between southern and northern Patagonia32–34. Thus, evidence at hand suggests that the Maastrichtian vertebrate fauna in southern Patagonia was different from that in northern Patagonia. It is noteworthy that the former had, instead, several taxa in common with Australia (
|
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|
<emphasis box="[740,767,1867,1888]" italics="true" pageId="3" pageNumber="4">e.g</emphasis>
|
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|
.,
|
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<taxonomicName authorityName=", Bonaparte" authorityYear="1837" box="[116,257,1894,1915]" class="Mammalia" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="3" pageNumber="4" phylum="Chordata" rank="order">Monotremata</taxonomicName>
|
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|
,
|
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|
<taxonomicName box="[275,439,1894,1916]" family="Megaraptoridae" higherTaxonomySource="GBIF" kingdom="Animalia" pageId="3" pageNumber="4" phylum="Chordata" rank="family">Megaraptoridae</taxonomicName>
|
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|
|
). It is likely that a latitudinal zonation of environmental conditions (i.e., dry and warm in northern Patagonia versus humid and cold in southern Patagonia) controlled the distribution and partial abundance of the above-mentioned vertebrate clades.
|
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|
|
</paragraph>
|
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|
|
<footnote box="[430,1131,2007,2023]" pageId="2" pageNumber="3">
|
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|
|
<paragraph blockId="2.[430,1131,2007,2023]" box="[430,1131,2007,2023]" pageId="2" pageNumber="3">(2023) 6:146 | https://doi.org/10.1038/s42003-023-04498-7 | www.nature.com/commsbio</paragraph>
|
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|
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</footnote>
|
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<paragraph blockId="3.[810,1472,136,1776]" pageId="3" pageNumber="4">The presence of monotremes in the southern La Anita fossil site (which occupied a paleolatitude of approximately 60° S during the Maastrichtian, roughly the same as that of southern Australia35) is congruent with the interpretation by Flannery et al.2 that monotremes evolved under humid, cool and densely forested environments in circumpolar Gondwana. Some authors already proposed that certain anatomical and physiological characteristics of living monotremes (e.g., low metabolism, a mechanoreceptive and electroreceptive beak for probe feeding, and relatively large body size) may have evolved in the context of polar environments2,18,36.</paragraph>
|
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|
<paragraph blockId="3.[810,1472,136,1776]" pageId="3" pageNumber="4">
|
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|
|
The crown morphology of the only available molar of
|
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|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" genus="Patagorhynchus" pageId="3" pageNumber="4" rank="genus">
|
|||
|
|
<emphasis italics="true" pageId="3" pageNumber="4">Patagorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
is closely similar to that of the Paleogene
|
|||
|
|
<taxonomicName class="Mammalia" family="Ornithorhynchidae" genus="Monotrematum" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="3" pageNumber="4" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis italics="true" pageId="3" pageNumber="4">Monotrematum</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
and the Neogene
|
|||
|
|
<taxonomicName authorityName="Woodburne & Tedford" authorityYear="1975" box="[1135,1249,555,576]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="3" pageNumber="4" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1135,1249,555,576]" italics="true" pageId="3" pageNumber="4">Obdurodon</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
, revealing a highly conservative dental morphology for toothed monotremes15. Remarkably, this molar pattern underwent only minor changes for approximately 60 million years from the Late Cretaceous through to Miocene times. This duration of stasis in dental morphology considerably exceeds that seen in other mammalian groups (
|
|||
|
|
<emphasis box="[896,922,723,744]" italics="true" pageId="3" pageNumber="4">e.g</emphasis>
|
|||
|
|
., therians and dryolestoids37–40).
|
|||
|
|
</paragraph>
|
|||
|
|
<paragraph blockId="3.[810,1472,136,1776]" pageId="3" pageNumber="4">
|
|||
|
|
The labiolingually broad segment of the molar of
|
|||
|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" genus="Patagorhynchus" pageId="3" pageNumber="4" rank="genus">
|
|||
|
|
<emphasis italics="true" pageId="3" pageNumber="4">Patagorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
and the reduction in the number of teeth (eventually restricted to only two upper molars inferred for
|
|||
|
|
<taxonomicName box="[1294,1453,807,828]" class="Mammalia" family="Ornithorhynchidae" genus="Monotrematum" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="3" pageNumber="4" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1294,1453,807,828]" italics="true" pageId="3" pageNumber="4">Monotrematum</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
2) may be congruent with the duck-billed morphology of the snout documented in more derived ornithorhynchids. In addition, the presence of a hypertrophied mandibular canal in
|
|||
|
|
<taxonomicName authorityName="Rich, Vickers-Rich, Constantine, Flannery, Kool & van Klaveren" authorityYear="1999" box="[1351,1471,890,911]" class="Mammalia" family="Teinolophidae" genus="Teinolophos" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="3" pageNumber="4" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1351,1471,890,911]" italics="true" pageId="3" pageNumber="4">Teinolophos</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
suggests the development of electroreception occurred early in the evolutionary history of
|
|||
|
|
<taxonomicName authorityName=", Bonaparte" authorityYear="1837" box="[1045,1184,946,967]" class="Mammalia" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="3" pageNumber="4" phylum="Chordata" rank="order">Monotremata</taxonomicName>
|
|||
|
|
and that the acquisition of a specialized duckbill for high-resolution aquatic electroreception is unique to the clade39. Based on such evidence, we hypothesize that a highly sensitive duck-billed snout is likely to have already been present in Late Cretaceous monotremes, such as
|
|||
|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" genus="Patagorhynchus" pageId="3" pageNumber="4" rank="genus">
|
|||
|
|
<emphasis italics="true" pageId="3" pageNumber="4">Patagorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
. Apparently, a similar anatomical inference could be made for the rest of the body, as suggested by the morphology of the distal femur of
|
|||
|
|
<taxonomicName box="[1020,1179,1141,1162]" class="Mammalia" family="Ornithorhynchidae" genus="Monotrematum" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="3" pageNumber="4" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1020,1179,1141,1162]" italics="true" pageId="3" pageNumber="4">Monotrematum</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
41 being almost identical to that of the living platypus. As in
|
|||
|
|
<taxonomicName box="[1211,1381,1169,1190]" class="Mammalia" family="Ornithorhynchidae" genus="Ornithorhynchus" kingdom="Animalia" order="Monotremata" pageId="3" pageNumber="4" phylum="Chordata" rank="genus">
|
|||
|
|
<emphasis box="[1211,1381,1169,1190]" italics="true" pageId="3" pageNumber="4">Ornithorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
, extinct monotremes may have had a sprawling posture of their hind limbs, and eventually adapted for swimming42. The possibility that
|
|||
|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" box="[860,1019,1252,1273]" genus="Patagorhynchus" pageId="3" pageNumber="4" rank="genus">
|
|||
|
|
<emphasis box="[860,1019,1252,1273]" italics="true" pageId="3" pageNumber="4">Patagorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
had already acquired ecological and behavioral characteristics similar to those of the living platypus, which inhabits ponds and lakes, is congruent with sedimentological evidence suggesting that such environments were prevalent during deposition of the Chorrillo Formation7, as well as with occurrences of
|
|||
|
|
<taxonomicName box="[972,1124,1392,1414]" class="Magnoliopsida" family="Nymphaeaceae" kingdom="Plantae" order="Nymphaeales" pageId="3" pageNumber="4" phylum="Tracheophyta" rank="family">Nymphaeaceae</taxonomicName>
|
|||
|
|
aquatic plants, freshwater snails and abundant larvae of chironomid insects, with the latter two invertebrates constituting part of the food for the living platypuses8,36,43.
|
|||
|
|
</paragraph>
|
|||
|
|
<caption ID-DOI="http://doi.org/10.5281/zenodo.7664998" ID-Zenodo-Dep="7664998" httpUri="https://zenodo.org/record/7664998/files/figure.png" pageId="3" pageNumber="4" startId="3.[116,146,1112,1132]" targetBox="[127,766,136,1087]" targetPageId="3">
|
|||
|
|
<paragraph blockId="3.[116,778,1112,1466]" pageId="3" pageNumber="4">
|
|||
|
|
<emphasis bold="true" pageId="3" pageNumber="4">
|
|||
|
|
Fig. 3 Simplified calibrated cladogram showing the phylogenetic affinities of
|
|||
|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" box="[229,449,1140,1159]" genus="Patagorhynchus" pageId="3" pageNumber="4" rank="species" species="pascuali">
|
|||
|
|
<emphasis bold="true" box="[229,449,1140,1159]" italics="true" pageId="3" pageNumber="4">Patagorhynchus pascuali</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
.
|
|||
|
|
</emphasis>
|
|||
|
|
Basal Monotremaformes
|
|||
|
|
<superScript attach="left" box="[680,700,1137,1152]" fontSize="6" pageId="3" pageNumber="4">44</superScript>
|
|||
|
|
are indicated in red and
|
|||
|
|
<taxonomicName authorityName=", Bonaparte" authorityYear="1837" box="[301,422,1168,1187]" class="Mammalia" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="3" pageNumber="4" phylum="Chordata" rank="order">Monotremata</taxonomicName>
|
|||
|
|
in green. The Late Cretaceous (Maastrichtian) palaeogeographical map (based in Scotese
|
|||
|
|
<superScript attach="left" box="[634,652,1192,1207]" fontSize="6" pageId="3" pageNumber="4">35</superScript>
|
|||
|
|
) indicates the fossiliferous sites that yielded fossil toothed monotremes and distribution of the extant platypus
|
|||
|
|
<taxonomicName baseAuthorityName="Shaw" baseAuthorityYear="1799" box="[320,532,1252,1271]" class="Mammalia" family="Ornithorhynchidae" genus="Ornithorhynchus" kingdom="Animalia" order="Monotremata" pageId="3" pageNumber="4" phylum="Chordata" rank="species" species="anatinus">
|
|||
|
|
<emphasis box="[320,532,1252,1271]" italics="true" pageId="3" pageNumber="4">Ornithorhynchus anatinus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
shaded in light brown. [1], occurrence of
|
|||
|
|
<taxonomicName authority=", La Anita" authorityName="La Anita" box="[245,536,1280,1299]" genus="Patagorhynchus" pageId="3" pageNumber="4" rank="species" species="pascuali">
|
|||
|
|
<emphasis box="[245,450,1280,1299]" italics="true" pageId="3" pageNumber="4">Patagorhynchus pascuali</emphasis>
|
|||
|
|
, La Anita
|
|||
|
|
</taxonomicName>
|
|||
|
|
farm, Chorrillo Formation (Maastrichtian, Late Cretaceous); [2], occurrence of
|
|||
|
|
<taxonomicName authority=", Punta Peligro" authorityName="Punta Peligro" class="Mammalia" family="Ornithorhynchidae" genus="Monotrematum" higherTaxonomySource="GBIF" kingdom="Animalia" order="Monotremata" pageId="3" pageNumber="4" phylum="Chordata" rank="species" species="sudamericanum">
|
|||
|
|
<emphasis italics="true" pageId="3" pageNumber="4">Monotrematum sudamericanum</emphasis>
|
|||
|
|
, Punta Peligro
|
|||
|
|
</taxonomicName>
|
|||
|
|
locality, Salamanca Formation (Danian, lower Paleocene); [3], occurrence of
|
|||
|
|
<taxonomicName box="[394,533,1363,1382]" class="Mammalia" family="Ornithorhynchidae" genus="Obdurodon" kingdom="Animalia" order="Monotremata" pageId="3" pageNumber="4" phylum="Chordata" rank="species" species="undetermined">
|
|||
|
|
<emphasis box="[394,486,1363,1382]" italics="true" pageId="3" pageNumber="4">Obdurodon</emphasis>
|
|||
|
|
spp.
|
|||
|
|
</taxonomicName>
|
|||
|
|
, different localities from South Australia, Queensland, and New South Wales Oligocene-Pliocene); [4], Pleistocene occurrences and geographic distribution of extant
|
|||
|
|
<taxonomicName baseAuthorityName="Shaw" baseAuthorityYear="1799" box="[116,329,1447,1466]" class="Mammalia" family="Ornithorhynchidae" genus="Ornithorhynchus" kingdom="Animalia" order="Monotremata" pageId="3" pageNumber="4" phylum="Chordata" rank="species" species="anatinus">
|
|||
|
|
<emphasis box="[116,329,1447,1466]" italics="true" pageId="3" pageNumber="4">Ornithorhynchus anatinus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
.
|
|||
|
|
</paragraph>
|
|||
|
|
</caption>
|
|||
|
|
<paragraph blockId="3.[810,1472,136,1776]" pageId="3" pageNumber="4">
|
|||
|
|
Discovery of
|
|||
|
|
<taxonomicName authorityName="Chimento & Agnolín & Manabe & Tsuihiji & Rich & Vickers-Rich & Novas" authorityYear="2023" box="[968,1127,1503,1524]" genus="Patagorhynchus" pageId="3" pageNumber="4" rank="genus">
|
|||
|
|
<emphasis box="[968,1127,1503,1524]" italics="true" pageId="3" pageNumber="4">Patagorhynchus</emphasis>
|
|||
|
|
</taxonomicName>
|
|||
|
|
gives an insight into the degree of continuity between the terrestrial vertebrate faunas of western and eastern Gondwana during the Late Cretaceous, suggesting the lack of paleobiogeographic barriers to their dispersal prior to the deep-water opening of the Drake Passage and the Tasman Gateway. The diversification of monotremes towards the end of the Mesozoic suggested by the present discovery implies that an extensive and still unknown history of this clade of peculiar mammals awaits to be documented in Mesozoic beds in southern South America.
|
|||
|
|
</paragraph>
|
|||
|
|
</subSubSection>
|
|||
|
|
</treatment>
|
|||
|
|
</document>
|