603 lines
87 KiB
XML
603 lines
87 KiB
XML
<document ID-DOI="http://doi.org/10.5281/zenodo.6485782" ID-GBIF-Dataset="43fbd3b8-9934-4986-b4c6-d39725751fa4" ID-GBIF-Taxon="157099796" ID-Zenodo-Dep="6485782" approvalRequired="1" approvalRequired_for_bibRefs="1" checkinTime="1557417081988" checkinUser="plazi" docAuthor="Xu, Xing, Zheng, Xiaoting, Sullivan, Corwin, Wang, Xiaoli, Xing, Lida, Wang, Yan, Zhang, Xiaomei, O’Connor, Jingmai K., Zhang, Fucheng & Pan, Yanhong" docDate="2015" docId="03AB87A99F1FE0493333FB3BFEEF5FFA" docLanguage="en" docName="nature.521.14423.pdf" docOrigin="Nature 521" docStyle="DocumentStyle{}" docTitle="Yi qi Xu & Zheng & Sullivan & Wang & Xing & Wang & Zhang & O’Connor & Zhang & Pan 2015, gen. et sp. nov." docType="treatment" docVersion="10" lastPageId="3" lastPageNumber="73" masterDocId="FF92FFD19F1FE04A327CFFF7FFF85D5D" masterDocTitle="A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings" masterLastPageNumber="82" masterPageNumber="70" pageId="0" pageNumber="70" updateTime="1650932009381" 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>A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings</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>Xu, Xing</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>Zheng, Xiaoting</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>Sullivan, Corwin</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>Wang, Xiaoli</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>Xing, Lida</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>Wang, Yan</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>Zhang, Xiaomei</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>O’Connor, Jingmai K.</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>Zhang, Fucheng</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>Pan, Yanhong</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>Nature</mods:title>
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</mods:titleInfo>
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<mods:part>
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<mods:date>2015</mods:date>
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<mods:detail type="pubDate">
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<mods:number>2015-05-07</mods:number>
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</mods:detail>
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<mods:detail type="volume">
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<mods:number>521</mods:number>
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</mods:detail>
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<mods:extent unit="page">
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<mods:start>70</mods:start>
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<mods:end>82</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:classification>journal article</mods:classification>
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<mods:identifier type="DOI">10.1038/nature14423</mods:identifier>
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<mods:identifier type="GBIF-Dataset">43fbd3b8-9934-4986-b4c6-d39725751fa4</mods:identifier>
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<mods:identifier type="Zenodo-Dep">2688054</mods:identifier>
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<treatment ID-DOI="http://doi.org/10.5281/zenodo.6485782" ID-GBIF-Taxon="157099796" ID-Zenodo-Dep="6485782" LSID="urn:lsid:plazi:treatment:03AB87A99F1FE0493333FB3BFEEF5FFA" httpUri="http://treatment.plazi.org/id/03AB87A99F1FE0493333FB3BFEEF5FFA" lastPageId="3" lastPageNumber="73" pageId="0" pageNumber="70">
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<subSubSection box="[335,535,1228,1249]" pageId="0" pageNumber="70" type="nomenclature">
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<paragraph blockId="0.[98,771,534,1249]" box="[335,535,1228,1249]" pageId="0" pageNumber="70">
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<taxonomicName authority="Xu & Zheng & Sullivan & Wang & Xing & Wang & Zhang & O’Connor & Zhang & Pan, 2015" authorityName="Xu & Zheng & Sullivan & Wang & Xing & Wang & Zhang & O’Connor & Zhang & Pan" authorityYear="2015" box="[335,382,1228,1249]" class="Reptilia" family="Scansoriopterygidae" genus="Yi" higherTaxonomySource="GBIF,CoL" kingdom="Animalia" order="Dinosauria" pageId="0" pageNumber="70" phylum="Chordata" rank="species" species="qi" status="gen. et sp. nov.">
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<emphasis box="[335,382,1228,1249]" italics="true" pageId="0" pageNumber="70">Yi qi</emphasis>
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</taxonomicName>
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<taxonomicNameLabel box="[388,535,1228,1249]" pageId="0" pageNumber="70">gen. et sp. nov.</taxonomicNameLabel>
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</paragraph>
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</subSubSection>
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<subSubSection pageId="0" pageNumber="70" type="etymology">
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<paragraph blockId="0.[98,772,1277,1867]" pageId="0" pageNumber="70">
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<emphasis bold="true" box="[98,213,1277,1298]" pageId="0" pageNumber="70">Etymology.</emphasis>
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The generic and specific names are derived from Mandarin
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<taxonomicName box="[206,228,1306,1327]" pageId="0" pageNumber="70">
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<emphasis box="[206,228,1306,1327]" italics="true" pageId="0" pageNumber="70">Yi</emphasis>
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</taxonomicName>
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(wing) and
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<emphasis box="[357,376,1306,1327]" italics="true" pageId="0" pageNumber="70">qi</emphasis>
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(strange), respectively, referring to the bizarre wings of this animal. The intended pronunciation of the name is roughly ‘‘ee chee’’.
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</paragraph>
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</subSubSection>
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<subSubSection pageId="0" pageNumber="70" type="materials_examined">
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<materialsCitation ID-GBIF-Occurrence="2239524148" collectionCode="housed at the Shandong Tianyu Museum of Nature" country="China" county="Qinglong County" location="Callovian-Oxfordian stage 4, 11" municipality="Tiaojishan Formation" pageId="0" pageNumber="70" specimenCode="STM 31-2" specimenCount="1" stateProvince="Hebei Province" typeStatus="holotype">
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<paragraph blockId="0.[98,772,1277,1867]" pageId="0" pageNumber="70">
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<emphasis bold="true" box="[98,198,1391,1412]" pageId="0" pageNumber="70">
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<typeStatus box="[98,194,1391,1412]" pageId="0" pageNumber="70">Holotype</typeStatus>
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.
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</emphasis>
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<specimenCode box="[208,309,1391,1412]" pageId="0" pageNumber="70">STM 31-2</specimenCode>
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(
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<collectionCode pageId="0" pageNumber="70">housed at the Shandong Tianyu Museum of Nature</collectionCode>
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), an articulated partial skeleton with associated soft tissue preserved on a slab and counter slab. The specimen was collected by a local farmer, but its provenance and authenticity have been confirmed by multiple lines of evidence including sedimentology, taphonomy and computed tomography (CT) data (Extended Data
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<figureCitation box="[645,730,1533,1555]" captionStart-0="Figure 1" captionStart-1="Figure 2" captionStart-2="Figure 3" captionStart-3="Extended" captionStartId-0="1.[113,172,1346,1365]" captionStartId-1="2.[1042,1101,145,164]" captionStartId-2="2.[98,157,1728,1747]" captionStartId-3="7.[113,198,761,780]" captionTargetBox-0="[117,782,154,1316]" captionTargetBox-1="[98,1004,160,720]" captionTargetBox-2="[120,750,790,1706]" captionTargetBox-3="[468,1134,151,746]" captionTargetId-0="figure@1.[122,688,673,750]" captionTargetId-1="figure@2.[550,1005,157,533]" captionTargetId-2="figure@2.[398,487,1053,1591]" captionTargetId-3="figure@7.[468,1134,151,746]" captionTargetPageId-0="1" captionTargetPageId-1="2" captionTargetPageId-2="2" captionText-0="Figure 1 | Yi qi holotype (STM 31-2). a, b, Photograph (a) and line drawing (b) of specimen; c, skull and mandible in lateral view; d, premaxillary tooth in lateral view; e, left manus; f, styliform elements (the distally unexposed left styliform element articulates with the wrist, and the orientation of the right styliform element implies a similar relationship to the carpus even though its proximal part is missing). Light and dark grey shading indicates feathers and membranous tissues, respectively.an, angular; cv, cervical vertebrae;d, dentary; dr, dorsal ribs;emf,external mandibular fenestra; en, external naris; f, frontal; lf, left femur;lh, left humerus; lmd2–4, left manual digits 2–4; lmt, left metatarsals; lr, left radius; ls, left scapula; lse, left styliform element; lu, left ulna; mb, mandible; mcII–IV, metacarpals II–IV; n, nasal; or, orbit; p, parietal; phII1 to IV4, phalanges II-1 to IV-4; pma, premaxilla; rmd2–4, right manual digits 2–4; rf, right femur; rfi, right fibula; rh, right humerus; rmc, right metacarpals; rmt, right metatarsals; rr, right radius; rse, right styliform element; rt, right tibiotarsus; ru, right ulna; sk, skull. Scale bar, 2 cm." captionText-1="Figure 2 | Soft tissues preserved in Yi qi holotype (STM 31-2). a–e, Feathers above the skull (a), along the humerus (b) and along the tibiotarsus (c); isolated basally converging (d) and brush-like (e) feathers; f, sheet-like soft tissue associated with the right forelimb (yellow arrows point to patches of sheet-like soft tissue); g, comparison of sheet-like soft tissue (above digit II) and individual feathers (below digit II)." captionText-2="Figure 3 | Simplified coelurosaurian phylogeny showing the recovered position of Yi. The skeletal silhouette and two possible alternative planform reconstructions of Yi highlight the proportionally long and robust forelimbs and large leg feathers that Yi shares with other basal paravian theropods, indicating the presence of aerial capability, and the inferred membranous wings, a feature unique among known paravians but seen in most other gliding or flying tetrapods. Various uncertainties, such as how the styliform element is oriented and whether membranous tissue is present lateral to the trunk as in most volant tetrapods, imply that a variety of reconstructions of the aerodynamic apparatus of Yi are currently plausible (see Supplementary Information for additional possible reconstructions)." captionText-3="Extended Data Figure 4 | Volumetric model generated from superimposed CT slices. Because there is little density contrast between the fossil and the matrix, the outline of the fossil is somewhat vague." httpUri-0="https://zenodo.org/record/2688056/files/figure.png" httpUri-1="https://zenodo.org/record/2688060/files/figure.png" httpUri-2="https://zenodo.org/record/2688066/files/figure.png" httpUri-3="https://zenodo.org/record/2688078/files/figure.png" pageId="0" pageNumber="70">Figs 1–4</figureCitation>
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; see also Supplementary Information).
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</paragraph>
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<paragraph blockId="0.[98,772,1277,1867]" pageId="0" pageNumber="70">
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<emphasis bold="true" box="[98,311,1590,1612]" pageId="0" pageNumber="70">Locality and horizon.</emphasis>
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Mutoudeng,
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<collectingCounty box="[439,610,1590,1612]" pageId="0" pageNumber="70">Qinglong County</collectingCounty>
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,
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<collectingRegion box="[618,768,1590,1612]" country="China" name="Hebei" pageId="0" pageNumber="70">Hebei Province</collectingRegion>
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,
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<collectingCountry box="[98,160,1618,1640]" name="China" pageId="0" pageNumber="70">China</collectingCountry>
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.
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<collectingMunicipality box="[171,387,1618,1640]" pageId="0" pageNumber="70">Tiaojishan Formation</collectingMunicipality>
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,
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<location LSID="urn:lsid:plazi:treatment:03AB87A99F1FE0493333FB3BFEEF5FFA:8EDD60649F1FE04A33F3F9A5FD485B00" box="[399,688,1616,1640]" country="China" county="Qinglong County" municipality="Tiaojishan Formation" name="Callovian-Oxfordian stage 4, 11" pageId="0" pageNumber="70" stateProvince="Hebei Province">
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Callovian–Oxfordian stage
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<superScript attach="right" box="[662,688,1616,1629]" fontSize="5" pageId="0" pageNumber="70">
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<bibRefCitation author="Xu, K." box="[662,671,1616,1629]" journalOrPublisher="Petroleum Industry Press" pageId="0" pageNumber="70" refId="ref2792" refString="4. Xu, K. et al. Jurassic System in the North of China (VII): The Stratigraphic Region of Northeast China (Petroleum Industry Press, 2003)." title="Jurassic System in the North of China (VII): The Stratigraphic Region of Northeast China" type="book" year="2003">4</bibRefCitation>
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,
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<bibRefCitation author="Sullivan, C." box="[673,688,1616,1629]" journalOrPublisher="J. Vertebr. Paleontol." pageId="0" pageNumber="70" pagination="243 - 280" part="34" refId="ref3064" refString="11. Sullivan, C. et al. The vertebrates of the Jurassic Daohugou Biota of northeastern China. J. Vertebr. Paleontol. 34, 243 - 280 (2014)." title="The vertebrates of the Jurassic Daohugou Biota of northeastern China" type="journal article" year="2014">11</bibRefCitation>
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</superScript>
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</location>
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. On the basis of the provenance of the specimen,
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<taxonomicName box="[519,569,1647,1668]" pageId="0" pageNumber="70">
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<emphasis box="[519,569,1647,1668]" italics="true" pageId="0" pageNumber="70">Yi qi</emphasis>
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</taxonomicName>
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is a member of the Daohugou (or Yanliao) Biota
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<bibRefCitation author="Irmis, R. B." box="[384,399,1672,1685]" journalOrPublisher="J. Vertebr. Paleontol" pageId="0" pageNumber="70" pagination="350 - 361" part="27" refId="ref3099" refString="12. Irmis, R. B. Axial skeletal ontogeny in the Parasuchia (Archosauria: Pseudosuchia) and its implications for ontogenetic determination in Archosaurs. J. Vertebr. Paleontol. 27, 350 - 361 (2007)." title="Axial skeletal ontogeny in the Parasuchia (Archosauria: Pseudosuchia) and its implications for ontogenetic determination in Archosaurs" type="journal article" year="2007">
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<superScript attach="left" box="[384,399,1672,1685]" fontSize="5" pageId="0" pageNumber="70">12</superScript>
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</bibRefCitation>
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.
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</paragraph>
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</materialsCitation>
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||
</subSubSection>
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||
<subSubSection lastPageId="1" lastPageNumber="71" pageId="0" pageNumber="70" type="diagnosis">
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<paragraph blockId="0.[98,772,1277,1867]" lastBlockId="0.[801,1475,534,1867]" pageId="0" pageNumber="70">
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<emphasis bold="true" box="[98,205,1704,1726]" pageId="0" pageNumber="70">Diagnosis.</emphasis>
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A scansoriopterygid theropod distinguishable from other scansoriopterygids in having a low midline crest along the nasals, a relatively small and posteriorly located external mandibular fenestra, tooth crowns that are symmetrical in lateral view and considerably wider mesiodistally than their corresponding roots, a humerus and ulna that are long relative to the tibiotarsus (length ratios are 1.16 and 1.08, respectively, compared to 0.96 and 0.78 in
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<taxonomicName box="[801,969,562,583]" class="Reptilia" family="Not" genus="Epidendrosaurus" higherTaxonomySource="CoL" kingdom="Animalia" order="Dinosauria" pageId="0" pageNumber="70" phylum="Chordata" rank="genus">
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<emphasis box="[801,969,562,583]" italics="true" pageId="0" pageNumber="70">Epidendrosaurus</emphasis>
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</taxonomicName>
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and 0.79 and 0.66 in
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<taxonomicName box="[1187,1323,562,583]" class="Reptilia" family="Not" genus="Epidexipteryx" higherTaxonomySource="CoL" kingdom="Animalia" order="Dinosauria" pageId="0" pageNumber="70" phylum="Chordata" rank="genus">
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<emphasis box="[1187,1323,562,583]" italics="true" pageId="0" pageNumber="70">Epidexipteryx</emphasis>
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</taxonomicName>
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), an extremely short humeral deltopectoral crest, and a long rod-like bone articulating with the wrist.
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</paragraph>
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<paragraph blockId="0.[801,1475,534,1867]" pageId="0" pageNumber="70">
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Key osteological features are as follows. STM 31-2 (
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<figureCitation box="[1311,1363,646,668]" captionStart="Figure 1" captionStartId="1.[113,172,1346,1365]" captionTargetBox="[117,782,154,1316]" captionTargetId="figure@1.[122,688,673,750]" captionTargetPageId="1" captionText="Figure 1 | Yi qi holotype (STM 31-2). a, b, Photograph (a) and line drawing (b) of specimen; c, skull and mandible in lateral view; d, premaxillary tooth in lateral view; e, left manus; f, styliform elements (the distally unexposed left styliform element articulates with the wrist, and the orientation of the right styliform element implies a similar relationship to the carpus even though its proximal part is missing). Light and dark grey shading indicates feathers and membranous tissues, respectively.an, angular; cv, cervical vertebrae;d, dentary; dr, dorsal ribs;emf,external mandibular fenestra; en, external naris; f, frontal; lf, left femur;lh, left humerus; lmd2–4, left manual digits 2–4; lmt, left metatarsals; lr, left radius; ls, left scapula; lse, left styliform element; lu, left ulna; mb, mandible; mcII–IV, metacarpals II–IV; n, nasal; or, orbit; p, parietal; phII1 to IV4, phalanges II-1 to IV-4; pma, premaxilla; rmd2–4, right manual digits 2–4; rf, right femur; rfi, right fibula; rh, right humerus; rmc, right metacarpals; rmt, right metatarsals; rr, right radius; rse, right styliform element; rt, right tibiotarsus; ru, right ulna; sk, skull. Scale bar, 2 cm." httpUri="https://zenodo.org/record/2688056/files/figure.png" pageId="0" pageNumber="70">Fig. 1</figureCitation>
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) is inferred to be an adult on the basis of the closed neurocentral sutures of the visible vertebrae, although this is not a universal criterion for maturity across archosaurian taxa
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<bibRefCitation author="Irmis, R. B." box="[1042,1057,727,740]" journalOrPublisher="J. Vertebr. Paleontol" pageId="0" pageNumber="70" pagination="350 - 361" part="27" refId="ref3099" refString="12. Irmis, R. B. Axial skeletal ontogeny in the Parasuchia (Archosauria: Pseudosuchia) and its implications for ontogenetic determination in Archosaurs. J. Vertebr. Paleontol. 27, 350 - 361 (2007)." title="Axial skeletal ontogeny in the Parasuchia (Archosauria: Pseudosuchia) and its implications for ontogenetic determination in Archosaurs" type="journal article" year="2007">
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<superScript attach="left" box="[1042,1057,727,740]" fontSize="5" pageId="0" pageNumber="70">12</superScript>
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</bibRefCitation>
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. Its body mass is estimated to be approximately 380 g, using an empirical equation
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<bibRefCitation author="Christiansen, P. & Farina, R. A." box="[1207,1222,755,768]" journalOrPublisher="Hist. Biol." pageId="0" pageNumber="70" pagination="85 - 92" part="16" refId="ref3142" refString="13. Christiansen, P. & Farina, R. A. Mass prediction in theropod dinosaurs. Hist. Biol. 16, 85 - 92 (2004)." title="Mass prediction in theropod dinosaurs" type="journal article" year="2004">
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<superScript attach="left" box="[1207,1222,755,768]" fontSize="5" pageId="0" pageNumber="70">13</superScript>
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</bibRefCitation>
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.
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</paragraph>
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<paragraph blockId="0.[801,1475,534,1867]" pageId="0" pageNumber="70">
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The skull and mandible are similar to those of other scansoriopterygids, and to a lesser degree to those of oviraptorosaurs and some basal birds such as
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<taxonomicName authorityName="Z.H.Zhou & F.C.Zhang" authorityYear="2002" box="[946,1039,841,862]" class="Reptilia" family="Not" genus="Sapeornis" higherTaxonomySource="CoL" kingdom="Animalia" order="Dinosauria" pageId="0" pageNumber="70" phylum="Chordata" rank="genus">
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<emphasis box="[946,1039,841,862]" italics="true" pageId="0" pageNumber="70">Sapeornis</emphasis>
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</taxonomicName>
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and
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<taxonomicName authorityName="Zhou & Zhang" authorityYear="2002" box="[1096,1191,841,862]" class="Reptilia" family="Not" genus="Jeholornis" higherTaxonomySource="CoL" kingdom="Animalia" order="Dinosauria" pageId="0" pageNumber="70" phylum="Chordata" rank="genus">
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<emphasis box="[1096,1191,841,862]" italics="true" pageId="0" pageNumber="70">Jeholornis</emphasis>
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</taxonomicName>
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<superScript attach="left" box="[1191,1248,838,851]" fontSize="5" pageId="0" pageNumber="70">11,14–17</superScript>
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: the skull is relatively robust, the snout is short (approximately 40% of skull length), the large premaxilla bears a well-developed subnarial process and extends further ventrally than the small maxilla, the parietal is anteroposteriorly long, the antorbital fossa is much smaller than the orbit, the infratemporal fenestra is large, the anterior end of the robust mandible is downturned, four slightly procumbent premaxillary teeth are located anterior to the external naris, the first premaxillary tooth is larger than the more posterior ones, and the anterior dentary teeth are strongly procumbent (
|
||
<figureCitation box="[937,992,1092,1115]" captionStart="Figure 1" captionStartId="1.[113,172,1346,1365]" captionTargetBox="[117,782,154,1316]" captionTargetId="figure@1.[122,688,673,750]" captionTargetPageId="1" captionText="Figure 1 | Yi qi holotype (STM 31-2). a, b, Photograph (a) and line drawing (b) of specimen; c, skull and mandible in lateral view; d, premaxillary tooth in lateral view; e, left manus; f, styliform elements (the distally unexposed left styliform element articulates with the wrist, and the orientation of the right styliform element implies a similar relationship to the carpus even though its proximal part is missing). Light and dark grey shading indicates feathers and membranous tissues, respectively.an, angular; cv, cervical vertebrae;d, dentary; dr, dorsal ribs;emf,external mandibular fenestra; en, external naris; f, frontal; lf, left femur;lh, left humerus; lmd2–4, left manual digits 2–4; lmt, left metatarsals; lr, left radius; ls, left scapula; lse, left styliform element; lu, left ulna; mb, mandible; mcII–IV, metacarpals II–IV; n, nasal; or, orbit; p, parietal; phII1 to IV4, phalanges II-1 to IV-4; pma, premaxilla; rmd2–4, right manual digits 2–4; rf, right femur; rfi, right fibula; rh, right humerus; rmc, right metacarpals; rmt, right metatarsals; rr, right radius; rse, right styliform element; rt, right tibiotarsus; ru, right ulna; sk, skull. Scale bar, 2 cm." httpUri="https://zenodo.org/record/2688056/files/figure.png" pageId="0" pageNumber="70">Fig. 1</figureCitation>
|
||
a–d). The thoracic appendage resembles that of other paravians in that the scapula is proportionally short and the humerus is long and robust, and further resembles that of other scansoriopterygids
|
||
<superScript attach="left" box="[939,978,1173,1186]" fontSize="5" pageId="0" pageNumber="70">
|
||
<bibRefCitation author="Zhang, F. & Zhou, Z. & Xu, X. & Wang, X. & Sullivan, C." box="[939,954,1173,1186]" journalOrPublisher="Nature" pageId="0" pageNumber="70" pagination="1105 - 1108" part="455" refId="ref3174" refString="14. Zhang, F., Zhou, Z., Xu, X., Wang, X. & Sullivan, C. A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers. Nature 455, 1105 - 1108 (2008)." title="A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers" type="journal article" year="2008">14</bibRefCitation>
|
||
–
|
||
<bibRefCitation author="Zhang, F. & Zhou, Z. & Xu, X. & Wang, X." box="[963,978,1173,1186]" journalOrPublisher="Naturwissenschaften" pageId="0" pageNumber="70" pagination="394 - 398" part="89" refId="ref3272" refString="16. Zhang, F., Zhou, Z., Xu, X. & Wang, X. A juvenile coelurosaurian theropod from China indicates arboreal habits. Naturwissenschaften 89, 394 - 398 (2002)." title="A juvenile coelurosaurian theropod from China indicates arboreal habits" type="journal article" year="2002">16</bibRefCitation>
|
||
</superScript>
|
||
in having a robust scapular blade, a short humeral deltopectoral crest, a straight ulna that is only slightly more robust than the radius, a metacarpal IV that is longer and more robust than metacarpal III (we identify the three manual digits of
|
||
<taxonomicName box="[1277,1299,1260,1281]" pageId="0" pageNumber="70">
|
||
<emphasis box="[1277,1299,1260,1281]" italics="true" pageId="0" pageNumber="70">Yi</emphasis>
|
||
</taxonomicName>
|
||
and other maniraptorans as II–III–IV, following the position-based numbering used in most ornithological literature, although we acknowledge that an anatomy-based I–II–III numbering convention is preferred by most dinosaur workers), and non-ungual phalanges of digit IV that are all greatly elongated (
|
||
<figureCitation box="[908,1023,1399,1421]" captionStart="Figure 1" captionStartId="1.[113,172,1346,1365]" captionTargetBox="[117,782,154,1316]" captionTargetId="figure@1.[122,688,673,750]" captionTargetPageId="1" captionText="Figure 1 | Yi qi holotype (STM 31-2). a, b, Photograph (a) and line drawing (b) of specimen; c, skull and mandible in lateral view; d, premaxillary tooth in lateral view; e, left manus; f, styliform elements (the distally unexposed left styliform element articulates with the wrist, and the orientation of the right styliform element implies a similar relationship to the carpus even though its proximal part is missing). Light and dark grey shading indicates feathers and membranous tissues, respectively.an, angular; cv, cervical vertebrae;d, dentary; dr, dorsal ribs;emf,external mandibular fenestra; en, external naris; f, frontal; lf, left femur;lh, left humerus; lmd2–4, left manual digits 2–4; lmt, left metatarsals; lr, left radius; ls, left scapula; lse, left styliform element; lu, left ulna; mb, mandible; mcII–IV, metacarpals II–IV; n, nasal; or, orbit; p, parietal; phII1 to IV4, phalanges II-1 to IV-4; pma, premaxilla; rmd2–4, right manual digits 2–4; rf, right femur; rfi, right fibula; rh, right humerus; rmc, right metacarpals; rmt, right metatarsals; rr, right radius; rse, right styliform element; rt, right tibiotarsus; ru, right ulna; sk, skull. Scale bar, 2 cm." httpUri="https://zenodo.org/record/2688056/files/figure.png" pageId="0" pageNumber="70">Fig. 1a, b, e</figureCitation>
|
||
).
|
||
</paragraph>
|
||
<paragraph blockId="0.[801,1475,534,1867]" lastBlockId="1.[816,1490,156,2002]" lastPageId="1" lastPageNumber="71" pageId="0" pageNumber="70">
|
||
The most striking feature of
|
||
<taxonomicName box="[1116,1138,1428,1449]" pageId="0" pageNumber="70">
|
||
<emphasis box="[1116,1138,1428,1449]" italics="true" pageId="0" pageNumber="70">Yi</emphasis>
|
||
</taxonomicName>
|
||
is the presence of an anomalous, slightly curved, distally tapered, rod-like structure (see Supplementary Information for further description), whose length considerably exceeds that of the ulna, associated with each wrist and apparently extending from the ulnar side of the carpus (
|
||
<figureCitation box="[1229,1335,1539,1561]" captionStart="Figure 1" captionStartId="1.[113,172,1346,1365]" captionTargetBox="[117,782,154,1316]" captionTargetId="figure@1.[122,688,673,750]" captionTargetPageId="1" captionText="Figure 1 | Yi qi holotype (STM 31-2). a, b, Photograph (a) and line drawing (b) of specimen; c, skull and mandible in lateral view; d, premaxillary tooth in lateral view; e, left manus; f, styliform elements (the distally unexposed left styliform element articulates with the wrist, and the orientation of the right styliform element implies a similar relationship to the carpus even though its proximal part is missing). Light and dark grey shading indicates feathers and membranous tissues, respectively.an, angular; cv, cervical vertebrae;d, dentary; dr, dorsal ribs;emf,external mandibular fenestra; en, external naris; f, frontal; lf, left femur;lh, left humerus; lmd2–4, left manual digits 2–4; lmt, left metatarsals; lr, left radius; ls, left scapula; lse, left styliform element; lu, left ulna; mb, mandible; mcII–IV, metacarpals II–IV; n, nasal; or, orbit; p, parietal; phII1 to IV4, phalanges II-1 to IV-4; pma, premaxilla; rmd2–4, right manual digits 2–4; rf, right femur; rfi, right fibula; rh, right humerus; rmc, right metacarpals; rmt, right metatarsals; rr, right radius; rse, right styliform element; rt, right tibiotarsus; ru, right ulna; sk, skull. Scale bar, 2 cm." httpUri="https://zenodo.org/record/2688056/files/figure.png" pageId="0" pageNumber="70">Fig. 1a, b, f</figureCitation>
|
||
and Extended Data
|
||
<figureCitation box="[852,907,1566,1589]" captionStart="Extended" captionStartId="8.[98,183,1365,1384]" captionTargetId="figure@8.[297,1276,151,1349]" captionTargetPageId="8" captionText="Extended Data Figure 5 | Photographs of preserved integumentary features of STM 31-2. a–c, Feathers over the neck (a), along the humerus (b) and along the humerus and ulna (c); d, isolated basally converging feathers; e, sheet-like" httpUri="https://zenodo.org/record/2702196/files/figure.png" pageId="0" pageNumber="70">Fig. 5</figureCitation>
|
||
). These structures resemble the preserved bones on the slab in colour, and in displaying a granular texture under magnification. Energy dispersive spectrometry (EDS) analysis of the elemental composition of the rod extending from the right wrist confirms that it is a bone (or possibly a skeletal element composed of calcified cartilage) and not a soft-tissue structure (Extended Data
|
||
<figureCitation box="[1312,1375,1706,1728]" captionStart="Extended" captionStartId="9.[113,198,880,899]" captionTargetBox="[236,1368,154,858]" captionTargetId="figure@9.[235,1368,151,864]" captionText="Extended Data Figure 6 | Elemental compositions of the styliform element and comparison samples based on EDS analyses. EDS spectra derived from: a, right manual phalanx II-1; b, right styliform element; c, feathers associated with right tibia; and d, sedimentary matrix." httpUri="https://zenodo.org/record/2688080/files/figure.png" pageId="0" pageNumber="70">Fig. 6</figureCitation>
|
||
; see also Supplementary Information). However, the rod-like bone of the forelimb of
|
||
<taxonomicName box="[884,906,1762,1783]" pageId="0" pageNumber="70">
|
||
<emphasis box="[884,906,1762,1783]" italics="true" pageId="0" pageNumber="70">Yi</emphasis>
|
||
</taxonomicName>
|
||
is morphologically unlike any normal theropod skeletal element. Indeed, no equivalent of the rod-like bone is known in any other dinosaur even outside Theropoda, but similar structures are present in a diverse array of extant and extinct flying or gliding tetrapod groups
|
||
<superScript attach="left" box="[267,298,1751,1764]" fontSize="5" pageId="1" pageNumber="71">
|
||
<bibRefCitation author="Schutt, W. A. Jr & Simmons, N. B." box="[267,274,1751,1764]" journalOrPublisher="J. Mamm. Evol." pageId="1" pageNumber="71" pagination="1 - 32" part="5" refId="ref2856" refString="6. Schutt, W. A. Jr & Simmons, N. B. Morphology and homology of the chiropteran calcar, with comments on the phylogenetic relationships of Archaeopteropus. J. Mamm. Evol. 5, 1 - 32 (1998)." title="Morphology and homology of the chiropteran calcar, with comments on the phylogenetic relationships of Archaeopteropus" type="journal article" year="1998">6</bibRefCitation>
|
||
–
|
||
<bibRefCitation author="Simmons, N. B. & Seymour, K. L. & Habersetzer, J. & Gunnell, G. F." box="[283,298,1751,1764]" journalOrPublisher="Nature" pageId="1" pageNumber="71" pagination="818 - 821" part="451" refId="ref3013" refString="10. Simmons, N. B., Seymour, K. L., Habersetzer, J. & Gunnell, G. F. Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation. Nature 451, 818 - 821 (2008)." title="Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation" type="journal article" year="2008">10</bibRefCitation>
|
||
</superScript>
|
||
. For example, a rod of bone or cartilage is attached to the wrists of petauristine squirrels
|
||
<bibRefCitation author="Johnson-Murray, J. L." box="[493,508,1779,1792]" journalOrPublisher="J. Mamm." pageId="1" pageNumber="71" pagination="374 - 384" part="58" refId="ref3357" refString="18. Johnson-Murray, J. L. Myology of the gliding membranes of some Petauristine rodents (genera: Glaucomys, Pteromys, Petinomys, and Petaurista). J. Mamm. 58, 374 - 384 (1977)." title="Myology of the gliding membranes of some Petauristine rodents (genera: Glaucomys, Pteromys, Petinomys, and Petaurista)" type="journal article" year="1977">
|
||
<superScript attach="right" box="[493,508,1779,1792]" fontSize="5" pageId="1" pageNumber="71">18</superScript>
|
||
</bibRefCitation>
|
||
; the elbows of anomalurid squirrels
|
||
<bibRefCitation author="Jackson, S. M." box="[197,212,1808,1821]" journalOrPublisher="Mammal Rev." pageId="1" pageNumber="71" pagination="9 - 30" part="30" refId="ref3400" refString="19. Jackson, S. M. Glide angle in the genus Petaurus and a review of gliding mammals. Mammal Rev. 30, 9 - 30 (2000)." title="Glide angle in the genus Petaurus and a review of gliding mammals" type="journal article" year="2000">
|
||
<superScript attach="right" box="[197,212,1808,1821]" fontSize="5" pageId="1" pageNumber="71">19</superScript>
|
||
</bibRefCitation>
|
||
, the gliding marsupial
|
||
<taxonomicName baseAuthorityName="Kerr" baseAuthorityYear="1792" box="[479,670,1810,1831]" class="Mammalia" family="Pseudocheiridae" genus="Petauroides" kingdom="Animalia" order="Diprotodontia" pageId="1" pageNumber="71" phylum="Chordata" rank="species" species="volans">
|
||
<emphasis box="[479,670,1810,1831]" italics="true" pageId="1" pageNumber="71">Petauroides volans</emphasis>
|
||
</taxonomicName>
|
||
<bibRefCitation author="Jackson, S. M." box="[670,685,1808,1821]" journalOrPublisher="Mammal Rev." pageId="1" pageNumber="71" pagination="9 - 30" part="30" refId="ref3400" refString="19. Jackson, S. M. Glide angle in the genus Petaurus and a review of gliding mammals. Mammal Rev. 30, 9 - 30 (2000)." title="Glide angle in the genus Petaurus and a review of gliding mammals" type="journal article" year="2000">
|
||
<superScript attach="left" box="[670,685,1808,1821]" fontSize="5" pageId="1" pageNumber="71">19</superScript>
|
||
</bibRefCitation>
|
||
and the Oligocene epoch eomyid rodent
|
||
<taxonomicName box="[437,577,1839,1860]" class="Mammalia" family="Eomyidae" genus="Eomys" higherTaxonomySource="GBIF" kingdom="Animalia" order="Rodentia" pageId="1" pageNumber="71" phylum="Chordata" rank="species" species="quercyi">
|
||
<emphasis box="[437,577,1839,1860]" italics="true" pageId="1" pageNumber="71">
|
||
<taxonomicName authorityName="Schlosser" authorityYear="1884" box="[437,500,1839,1860]" genus="Eomys" pageId="1" pageNumber="71" rank="genus">Eomys</taxonomicName>
|
||
quercyi
|
||
</emphasis>
|
||
</taxonomicName>
|
||
<bibRefCitation author="Storch, G. & Engesser, B. & Wuttke, M." box="[577,585,1836,1849]" journalOrPublisher="Nature" pageId="1" pageNumber="71" pagination="439 - 441" part="379" refId="ref2979" refString="9. Storch, G., Engesser, B. & Wuttke, M. Oldest fossil record of gliding in rodents. Nature 379, 439 - 441 (1996)." title="Oldest fossil record of gliding in rodents" type="journal article" year="1996">
|
||
<superScript attach="left" box="[577,585,1836,1849]" fontSize="5" pageId="1" pageNumber="71">9</superScript>
|
||
</bibRefCitation>
|
||
; the ankles of many bats, including some early ones
|
||
<superScript attach="left" box="[428,454,1864,1877]" fontSize="5" pageId="1" pageNumber="71">
|
||
<bibRefCitation author="Storch, G. & Engesser, B. & Wuttke, M." box="[428,436,1864,1877]" journalOrPublisher="Nature" pageId="1" pageNumber="71" pagination="439 - 441" part="379" refId="ref2979" refString="9. Storch, G., Engesser, B. & Wuttke, M. Oldest fossil record of gliding in rodents. Nature 379, 439 - 441 (1996)." title="Oldest fossil record of gliding in rodents" type="journal article" year="1996">9</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Simmons, N. B. & Seymour, K. L. & Habersetzer, J. & Gunnell, G. F." box="[438,454,1864,1877]" journalOrPublisher="Nature" pageId="1" pageNumber="71" pagination="818 - 821" part="451" refId="ref3013" refString="10. Simmons, N. B., Seymour, K. L., Habersetzer, J. & Gunnell, G. F. Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation. Nature 451, 818 - 821 (2008)." title="Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation" type="journal article" year="2008">10</bibRefCitation>
|
||
</superScript>
|
||
; and the wrists of all pterosaurs
|
||
<bibRefCitation author="Bennett, S. C." box="[779,787,1864,1877]" journalOrPublisher="J. Vertebr. Paleontol." pageId="1" pageNumber="71" pagination="881 - 891" part="27" refId="ref2946" refString="8. Bennett, S. C. Articulation and function of the pteroid bone of pterosaurs. J. Vertebr. Paleontol. 27, 881 - 891 (2007)." title="Articulation and function of the pteroid bone of pterosaurs" type="journal article" year="2007">
|
||
<superScript attach="right" box="[779,787,1864,1877]" fontSize="5" pageId="1" pageNumber="71">8</superScript>
|
||
</bibRefCitation>
|
||
(that is, the pteroid). In particular, the rod-like bone of
|
||
<taxonomicName box="[647,669,1896,1917]" pageId="1" pageNumber="71">
|
||
<emphasis box="[647,669,1896,1917]" italics="true" pageId="1" pageNumber="71">Yi</emphasis>
|
||
</taxonomicName>
|
||
is strikingly similar to the enlarged carpally situated element seen in some petauristines
|
||
<bibRefCitation author="Thorington, R. W. Jr & Darrow, K. A. C. J." box="[175,182,1949,1961]" journalOrPublisher="J. Mamm." pageId="1" pageNumber="71" pagination="245 - 250" part="79" refId="ref2904" refString="7. Thorington, R. W. Jr & Darrow, K. A. C. J. Wing tip anatomy and aerodynamics in flying squirrels. J. Mamm. 79, 245 - 250 (1998)." title="Wing tip anatomy and aerodynamics in flying squirrels" type="journal article" year="1998">
|
||
<superScript attach="right" box="[175,182,1949,1961]" fontSize="5" pageId="1" pageNumber="71">7</superScript>
|
||
</bibRefCitation>
|
||
, including the Japanese giant flying squirrel
|
||
<taxonomicName baseAuthorityName="Temminck" baseAuthorityYear="1827" class="Mammalia" family="Sciuridae" genus="Petaurista" kingdom="Animalia" order="Rodentia" pageId="1" pageNumber="71" phylum="Chordata" rank="species" species="leucogenys">
|
||
<emphasis italics="true" pageId="1" pageNumber="71">Petaurista leucogenys</emphasis>
|
||
</taxonomicName>
|
||
(Extended Data
|
||
<figureCitation box="[325,378,1980,2002]" captionStart="Extended" captionStartId="10.[98,183,1191,1210]" captionTargetBox="[225,1350,151,1169]" captionTargetId="figure@10.[220,1353,151,1175]" captionTargetPageId="10" captionText="Extended Data Figure 7 | Aerodynamic apparatuses in Yi and other tetrapods. a–c, Wing of Yi, Bat Model (a), Maniraptoran Model (b), and Frog Model (c); d, bat wing; e, pigeon wing; f, pterosaur wing; g, giant Japanese flying squirrel wing. Yellow colour indicates styliform element in a, b, c, d, f, and g." httpUri="https://zenodo.org/record/2688088/files/figure.png" pageId="1" pageNumber="71">Fig. 7</figureCitation>
|
||
; see also Supplementary Information). For convenience, we adopt ‘styliform element’ as a general term for unjointed, rod-like bony or cartilaginous structures that extend from distal limb joints in tetrapods.
|
||
</paragraph>
|
||
<footnote pageId="0" pageNumber="70">
|
||
<paragraph blockId="0.[98,1474,1890,1999]" pageId="0" pageNumber="70">
|
||
<superScript attach="right" box="[98,105,1890,1900]" fontSize="4" pageId="0" pageNumber="70">1</superScript>
|
||
Institute of Geology and Paleontology,Linyi University, Linyi City, Shandong 276005, China.
|
||
<bibRefCitation author="Xu, X." box="[740,747,1890,1900]" journalOrPublisher="Nature" pageId="0" pageNumber="70" pagination="335 - 340" part="421" refId="ref2724" refString="2. Xu, X. et al. Four-winged dinosaurs from China. Nature 421, 335 - 340 (2003)." title="Four-winged dinosaurs from China" type="journal article" year="2003">
|
||
<superScript attach="right" box="[740,747,1890,1900]" fontSize="4" pageId="0" pageNumber="70">2</superScript>
|
||
</bibRefCitation>
|
||
Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology,Chinese Academy of Sciences, Beijing 100044,China.
|
||
<bibRefCitation author="Hu, D. & Hou, L. & Zhang, L. & Xu, X." box="[813,820,1913,1923]" journalOrPublisher="Nature" pageId="0" pageNumber="70" pagination="640 - 643" part="461" refId="ref2748" refString="3. Hu, D., Hou, L., Zhang, L. & Xu, X. A pre- Archaeopteryx troodontid from China with long feathers on the metatarsus. Nature 461, 640 - 643 (2009)." title="A pre- Archaeopteryx troodontid from China with long feathers on the metatarsus" type="journal article" year="2009">
|
||
<superScript attach="right" box="[813,820,1913,1923]" fontSize="4" pageId="0" pageNumber="70">3</superScript>
|
||
</bibRefCitation>
|
||
Shandong Tianyu Museum of Nature, Pingyi, Shandong 273300, China.
|
||
<bibRefCitation author="Xu, K." box="[1320,1327,1913,1923]" journalOrPublisher="Petroleum Industry Press" pageId="0" pageNumber="70" refId="ref2792" refString="4. Xu, K. et al. Jurassic System in the North of China (VII): The Stratigraphic Region of Northeast China (Petroleum Industry Press, 2003)." title="Jurassic System in the North of China (VII): The Stratigraphic Region of Northeast China" type="book" year="2003">
|
||
<superScript attach="right" box="[1320,1327,1913,1923]" fontSize="4" pageId="0" pageNumber="70">4</superScript>
|
||
</bibRefCitation>
|
||
School of the Earth Sciences and Resources,China University of Geosciences, Beijing 100083,China.
|
||
<bibRefCitation author="Li, Q." box="[663,670,1936,1946]" journalOrPublisher="Nature" pageId="0" pageNumber="70" pagination="350 - 353" part="507" refId="ref2826" refString="5. Li, Q. et al. Melanosome evolution indicates a key physiological shift within feathered dinosaurs. Nature 507, 350 - 353 (2014)." title="Melanosome evolution indicates a key physiological shift within feathered dinosaurs" type="journal article" year="2014">
|
||
<superScript attach="right" box="[663,670,1936,1946]" fontSize="4" pageId="0" pageNumber="70">5</superScript>
|
||
</bibRefCitation>
|
||
Key Laboratory of Economic Stratigraphy and Palaeogeography of Chinese Academy of Sciences,Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China.
|
||
</paragraph>
|
||
<footnote box="[98,432,1984,1999]" pageId="0" pageNumber="70">
|
||
<paragraph blockId="0.[98,1474,1890,1999]" box="[98,432,1984,1999]" pageId="0" pageNumber="70">
|
||
<emphasis bold="true" box="[98,106,1985,1999]" italics="true" pageId="0" pageNumber="70">*</emphasis>
|
||
These authors contributed equally to this work.
|
||
</paragraph>
|
||
</footnote>
|
||
</footnote>
|
||
<paragraph blockId="1.[816,1490,156,2002]" pageId="1" pageNumber="71">
|
||
Integumentary structures and preserved melanosomes are as follows. Two major types of integumentary structure are preserved (see Supplementary Information for further description): feathers and membranous soft tissue (
|
||
<figureCitation box="[1073,1176,325,347]" captionStart="Figure 1" captionStartId="1.[113,172,1346,1365]" captionTargetBox="[117,782,154,1316]" captionTargetId="figure@1.[122,688,673,750]" captionTargetPageId="1" captionText="Figure 1 | Yi qi holotype (STM 31-2). a, b, Photograph (a) and line drawing (b) of specimen; c, skull and mandible in lateral view; d, premaxillary tooth in lateral view; e, left manus; f, styliform elements (the distally unexposed left styliform element articulates with the wrist, and the orientation of the right styliform element implies a similar relationship to the carpus even though its proximal part is missing). Light and dark grey shading indicates feathers and membranous tissues, respectively.an, angular; cv, cervical vertebrae;d, dentary; dr, dorsal ribs;emf,external mandibular fenestra; en, external naris; f, frontal; lf, left femur;lh, left humerus; lmd2–4, left manual digits 2–4; lmt, left metatarsals; lr, left radius; ls, left scapula; lse, left styliform element; lu, left ulna; mb, mandible; mcII–IV, metacarpals II–IV; n, nasal; or, orbit; p, parietal; phII1 to IV4, phalanges II-1 to IV-4; pma, premaxilla; rmd2–4, right manual digits 2–4; rf, right femur; rfi, right fibula; rh, right humerus; rmc, right metacarpals; rmt, right metatarsals; rr, right radius; rse, right styliform element; rt, right tibiotarsus; ru, right ulna; sk, skull. Scale bar, 2 cm." httpUri="https://zenodo.org/record/2688056/files/figure.png" pageId="1" pageNumber="71">Figs 1a, b</figureCitation>
|
||
,
|
||
<figureCitation box="[1190,1202,325,346]" captionStart="Figure 2" captionStartId="2.[1042,1101,145,164]" captionTargetId="figure@2.[550,1005,157,533]" captionTargetPageId="2" captionText="Figure 2 | Soft tissues preserved in Yi qi holotype (STM 31-2). a–e, Feathers above the skull (a), along the humerus (b) and along the tibiotarsus (c); isolated basally converging (d) and brush-like (e) feathers; f, sheet-like soft tissue associated with the right forelimb (yellow arrows point to patches of sheet-like soft tissue); g, comparison of sheet-like soft tissue (above digit II) and individual feathers (below digit II)." httpUri="https://zenodo.org/record/2688060/files/figure.png" pageId="1" pageNumber="71">2</figureCitation>
|
||
and Extended Data
|
||
<figureCitation box="[1418,1478,324,347]" captionStart="Extended" captionStartId="8.[98,183,1365,1384]" captionTargetId="figure@8.[297,1276,151,1349]" captionTargetPageId="8" captionText="Extended Data Figure 5 | Photographs of preserved integumentary features of STM 31-2. a–c, Feathers over the neck (a), along the humerus (b) and along the humerus and ulna (c); d, isolated basally converging feathers; e, sheet-like" httpUri="https://zenodo.org/record/2702196/files/figure.png" pageId="1" pageNumber="71">Fig. 5</figureCitation>
|
||
). Thin stiff filamentous feathers are distributed around the skull (15– 20 mm long;
|
||
<figureCitation box="[953,1023,381,403]" captionStart="Figure 2" captionStartId="2.[1042,1101,145,164]" captionTargetId="figure@2.[550,1005,157,533]" captionTargetPageId="2" captionText="Figure 2 | Soft tissues preserved in Yi qi holotype (STM 31-2). a–e, Feathers above the skull (a), along the humerus (b) and along the tibiotarsus (c); isolated basally converging (d) and brush-like (e) feathers; f, sheet-like soft tissue associated with the right forelimb (yellow arrows point to patches of sheet-like soft tissue); g, comparison of sheet-like soft tissue (above digit II) and individual feathers (below digit II)." httpUri="https://zenodo.org/record/2688060/files/figure.png" pageId="1" pageNumber="71">Fig. 2a</figureCitation>
|
||
), and both above and below the neck (about 30 mm long; Extended Data
|
||
<figureCitation box="[1110,1182,408,431]" captionStart="Extended" captionStartId="8.[98,183,1365,1384]" captionTargetId="figure@8.[297,1276,151,1349]" captionTargetPageId="8" captionText="Extended Data Figure 5 | Photographs of preserved integumentary features of STM 31-2. a–c, Feathers over the neck (a), along the humerus (b) and along the humerus and ulna (c); d, isolated basally converging feathers; e, sheet-like" httpUri="https://zenodo.org/record/2702196/files/figure.png" pageId="1" pageNumber="71">Fig. 5a</figureCitation>
|
||
). The feathers attached to the forelimb (35–60 mm long;
|
||
<figureCitation box="[1091,1161,437,459]" captionStart="Figure 2" captionStartId="2.[1042,1101,145,164]" captionTargetId="figure@2.[550,1005,157,533]" captionTargetPageId="2" captionText="Figure 2 | Soft tissues preserved in Yi qi holotype (STM 31-2). a–e, Feathers above the skull (a), along the humerus (b) and along the tibiotarsus (c); isolated basally converging (d) and brush-like (e) feathers; f, sheet-like soft tissue associated with the right forelimb (yellow arrows point to patches of sheet-like soft tissue); g, comparison of sheet-like soft tissue (above digit II) and individual feathers (below digit II)." httpUri="https://zenodo.org/record/2688060/files/figure.png" pageId="1" pageNumber="71">Fig. 2b</figureCitation>
|
||
and Extended Data
|
||
<figureCitation box="[1379,1477,436,459]" captionStart="Extended" captionStartId="8.[98,183,1365,1384]" captionTargetId="figure@8.[297,1276,151,1349]" captionTargetPageId="8" captionText="Extended Data Figure 5 | Photographs of preserved integumentary features of STM 31-2. a–c, Feathers over the neck (a), along the humerus (b) and along the humerus and ulna (c); d, isolated basally converging feathers; e, sheet-like" httpUri="https://zenodo.org/record/2702196/files/figure.png" pageId="1" pageNumber="71">Fig. 5b, c</figureCitation>
|
||
), and to the hindlimb including the metatarsus (up to 60 mm long;
|
||
<figureCitation box="[816,883,493,515]" captionStart="Figure 2" captionStartId="2.[1042,1101,145,164]" captionTargetId="figure@2.[550,1005,157,533]" captionTargetPageId="2" captionText="Figure 2 | Soft tissues preserved in Yi qi holotype (STM 31-2). a–e, Feathers above the skull (a), along the humerus (b) and along the tibiotarsus (c); isolated basally converging (d) and brush-like (e) feathers; f, sheet-like soft tissue associated with the right forelimb (yellow arrows point to patches of sheet-like soft tissue); g, comparison of sheet-like soft tissue (above digit II) and individual feathers (below digit II)." httpUri="https://zenodo.org/record/2688060/files/figure.png" pageId="1" pageNumber="71">Fig. 2c</figureCitation>
|
||
and Extended Data
|
||
<figureCitation box="[1093,1162,492,515]" captionStart="Extended" captionStartId="8.[98,183,1365,1384]" captionTargetId="figure@8.[297,1276,151,1349]" captionTargetPageId="8" captionText="Extended Data Figure 5 | Photographs of preserved integumentary features of STM 31-2. a–c, Feathers over the neck (a), along the humerus (b) and along the humerus and ulna (c); d, isolated basally converging feathers; e, sheet-like" httpUri="https://zenodo.org/record/2702196/files/figure.png" pageId="1" pageNumber="71">Fig. 5e</figureCitation>
|
||
), are much larger than the skull and neck feathers. Some of the filamentous feathers, including those on the skull and neck, appear to exhibit a simple branching pattern, but their dense preservation makes morphological details difficult to observe. Nevertheless, some isolated feathers clearly comprise multiple radiating filaments (
|
||
<figureCitation box="[1009,1075,632,654]" captionStart="Figure 2" captionStartId="2.[1042,1101,145,164]" captionTargetId="figure@2.[550,1005,157,533]" captionTargetPageId="2" captionText="Figure 2 | Soft tissues preserved in Yi qi holotype (STM 31-2). a–e, Feathers above the skull (a), along the humerus (b) and along the tibiotarsus (c); isolated basally converging (d) and brush-like (e) feathers; f, sheet-like soft tissue associated with the right forelimb (yellow arrows point to patches of sheet-like soft tissue); g, comparison of sheet-like soft tissue (above digit II) and individual feathers (below digit II)." httpUri="https://zenodo.org/record/2688060/files/figure.png" pageId="1" pageNumber="71">Fig. 2d</figureCitation>
|
||
and Extended Data
|
||
<figureCitation box="[1265,1331,632,655]" captionStart="Extended" captionStartId="8.[98,183,1365,1384]" captionTargetId="figure@8.[297,1276,151,1349]" captionTargetPageId="8" captionText="Extended Data Figure 5 | Photographs of preserved integumentary features of STM 31-2. a–c, Feathers over the neck (a), along the humerus (b) and along the humerus and ulna (c); d, isolated basally converging feathers; e, sheet-like" httpUri="https://zenodo.org/record/2702196/files/figure.png" pageId="1" pageNumber="71">Fig. 5d</figureCitation>
|
||
), and the majority of the limb feathers have a unique paintbrush-like morphology (
|
||
<figureCitation box="[823,893,688,711]" captionStart="Figure 2" captionStartId="2.[1042,1101,145,164]" captionTargetId="figure@2.[550,1005,157,533]" captionTargetPageId="2" captionText="Figure 2 | Soft tissues preserved in Yi qi holotype (STM 31-2). a–e, Feathers above the skull (a), along the humerus (b) and along the tibiotarsus (c); isolated basally converging (d) and brush-like (e) feathers; f, sheet-like soft tissue associated with the right forelimb (yellow arrows point to patches of sheet-like soft tissue); g, comparison of sheet-like soft tissue (above digit II) and individual feathers (below digit II)." httpUri="https://zenodo.org/record/2688060/files/figure.png" pageId="1" pageNumber="71">Fig. 2e</figureCitation>
|
||
): the proximal three-fourths of each feather is a wide (about 1.2 mm), undifferentiated shaft-like structure, whereas the distal part is composed of numerous near-parallel filaments.
|
||
</paragraph>
|
||
<paragraph blockId="1.[816,1490,156,2002]" pageId="1" pageNumber="71">
|
||
Several patches of membranous soft tissue are exposed around the styliform element and digits in both hands (
|
||
<figureCitation box="[1233,1325,801,823]" captionStart="Figure 1" captionStartId="1.[113,172,1346,1365]" captionTargetBox="[117,782,154,1316]" captionTargetId="figure@1.[122,688,673,750]" captionTargetPageId="1" captionText="Figure 1 | Yi qi holotype (STM 31-2). a, b, Photograph (a) and line drawing (b) of specimen; c, skull and mandible in lateral view; d, premaxillary tooth in lateral view; e, left manus; f, styliform elements (the distally unexposed left styliform element articulates with the wrist, and the orientation of the right styliform element implies a similar relationship to the carpus even though its proximal part is missing). Light and dark grey shading indicates feathers and membranous tissues, respectively.an, angular; cv, cervical vertebrae;d, dentary; dr, dorsal ribs;emf,external mandibular fenestra; en, external naris; f, frontal; lf, left femur;lh, left humerus; lmd2–4, left manual digits 2–4; lmt, left metatarsals; lr, left radius; ls, left scapula; lse, left styliform element; lu, left ulna; mb, mandible; mcII–IV, metacarpals II–IV; n, nasal; or, orbit; p, parietal; phII1 to IV4, phalanges II-1 to IV-4; pma, premaxilla; rmd2–4, right manual digits 2–4; rf, right femur; rfi, right fibula; rh, right humerus; rmc, right metacarpals; rmt, right metatarsals; rr, right radius; rse, right styliform element; rt, right tibiotarsus; ru, right ulna; sk, skull. Scale bar, 2 cm." httpUri="https://zenodo.org/record/2688056/files/figure.png" pageId="1" pageNumber="71">Figs 1a, b</figureCitation>
|
||
,
|
||
<figureCitation box="[1333,1352,801,823]" captionStart="Figure 2" captionStartId="2.[1042,1101,145,164]" captionTargetId="figure@2.[550,1005,157,533]" captionTargetPageId="2" captionText="Figure 2 | Soft tissues preserved in Yi qi holotype (STM 31-2). a–e, Feathers above the skull (a), along the humerus (b) and along the tibiotarsus (c); isolated basally converging (d) and brush-like (e) feathers; f, sheet-like soft tissue associated with the right forelimb (yellow arrows point to patches of sheet-like soft tissue); g, comparison of sheet-like soft tissue (above digit II) and individual feathers (below digit II)." httpUri="https://zenodo.org/record/2688060/files/figure.png" pageId="1" pageNumber="71">2f</figureCitation>
|
||
and Extended Data
|
||
<figureCitation box="[867,950,829,851]" captionStart="Extended" captionStartId="8.[98,183,1365,1384]" captionTargetId="figure@8.[297,1276,151,1349]" captionTargetPageId="8" captionText="Extended Data Figure 5 | Photographs of preserved integumentary features of STM 31-2. a–c, Feathers over the neck (a), along the humerus (b) and along the humerus and ulna (c); d, isolated basally converging feathers; e, sheet-like" httpUri="https://zenodo.org/record/2702196/files/figure.png" pageId="1" pageNumber="71">Fig. 5f, g</figureCitation>
|
||
). Additional patches appear to exist, but cannot be easily exposed (see Supplementary Information). The tissue has a sheet-like appearance, making it clearly distinguishable from the individual filaments or small groups of filaments that represent feathers (
|
||
<figureCitation box="[1408,1478,913,936]" captionStart="Figure 2" captionStartId="2.[1042,1101,145,164]" captionTargetId="figure@2.[550,1005,157,533]" captionTargetPageId="2" captionText="Figure 2 | Soft tissues preserved in Yi qi holotype (STM 31-2). a–e, Feathers above the skull (a), along the humerus (b) and along the tibiotarsus (c); isolated basally converging (d) and brush-like (e) feathers; f, sheet-like soft tissue associated with the right forelimb (yellow arrows point to patches of sheet-like soft tissue); g, comparison of sheet-like soft tissue (above digit II) and individual feathers (below digit II)." httpUri="https://zenodo.org/record/2688060/files/figure.png" pageId="1" pageNumber="71">Fig. 2g</figureCitation>
|
||
), and in some areas displays prominent ripple-like striations that may represent either fibres or closely spaced folds. The membranous tissue does not closely resemble any type of integumentary structure previously reported in theropods from the Mesozoic era deposits of northeastern China.
|
||
</paragraph>
|
||
<paragraph blockId="1.[816,1490,156,2002]" pageId="1" pageNumber="71">
|
||
We examined the integumentary structures using scanning electron microscopy (Extended Data
|
||
<figureCitation box="[1104,1162,1110,1132]" captionStart="Extended" captionStartId="11.[113,198,1047,1066]" captionTargetId="figure@11.[235,1368,151,1031]" captionTargetPageId="11" captionText="Extended Data Figure 8 | Scanning electron microscopy sample locations. Numbered circles indicate the locations of samples from the slab and counter slab. 1, distal part of cranial feathers; 2, middle part of tibial feathers; 3, distal part of humeral feathers; 4, distal part of ulnar feathers; 5, proximal part of" figureDoi="http://doi.org/10.5281/zenodo.6485793" httpUri="https://zenodo.org/record/6485793/files/figure.png" pageId="1" pageNumber="71">Fig. 8</figureCitation>
|
||
), revealing what we interpret as preserved melanosomes on both feathers and membranous tissue patches (although several studies have questioned the identification of melanosomes in theropod fossils
|
||
<superScript attach="left" box="[1158,1192,1191,1204]" fontSize="5" pageId="1" pageNumber="71">
|
||
<bibRefCitation author="Feduccia, A." box="[1158,1174,1191,1204]" journalOrPublisher="Auk" pageId="1" pageNumber="71" pagination="1 - 12" part="130" refId="ref3433" refString="20. Feduccia, A. Bird origins anew. Auk 130, 1 - 12 (2013)." title="Bird origins anew" type="journal article" year="2013">20</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Moyer, A. E." box="[1177,1192,1191,1204]" journalOrPublisher="Sci. Rep." pageId="1" pageNumber="71" pagination="4233" part="4" refId="ref3453" refString="21. Moyer, A. E. et al. Melanosomes or microbes: testing an alternative hypothesis for the origin of microbodies in fossil feathers. Sci. Rep. 4, 4233 (2014)." title="Melanosomes or microbes: testing an alternative hypothesis for the origin of microbodies in fossil feathers" type="journal article" year="2014">21</bibRefCitation>
|
||
</superScript>
|
||
). The melanosomes are highly variable in size (long axis 300–2,100 nm), shape (aspect ratio of 1.0 to 3.6) and density (Extended Data
|
||
<figureCitation box="[1136,1191,1250,1272]" captionStart="Extended" captionStartId="12.[98,183,1535,1554]" captionTargetBox="[220,1353,155,1519]" captionTargetId="figure@12.[220,1353,151,1519]" captionTargetPageId="12" captionText="Extended Data Figure 9 | Scanning electron microscopy images of melanosomes and melanosome impressions preserved in Yi qi holotype (STM 31-2). a–m, Note the high morphological diversity of the preserved melanosomes in the feathers, which include: densely distributed, small round phaeomelanosomes and sparsely distributed, medium-sized oval eumelanosomes in the feathers near the skull (a); medium-sized elongate elliptical eumelanosomes in the feathers near the skull (b, c), neck (d, e), humerus (f, g), and ulna (h, i, j); and large oval and elliptical eumelanosomes in the feathers near the tibiotarsus (k, l). The subspherical phaeomelanosomes in the sheet-like soft tissue (m) appear to be less densely distributed than the melanosomes in the feathers." httpUri="https://zenodo.org/record/2688096/files/figure.png" pageId="1" pageNumber="71">Fig. 9</figureCitation>
|
||
). It is noteworthy that some of the preserved melanosomes are among the largest known from either fossil or modern feathers
|
||
<bibRefCitation author="Li, Q." box="[1053,1060,1303,1316]" journalOrPublisher="Nature" pageId="1" pageNumber="71" pagination="350 - 353" part="507" refId="ref2826" refString="5. Li, Q. et al. Melanosome evolution indicates a key physiological shift within feathered dinosaurs. Nature 507, 350 - 353 (2014)." title="Melanosome evolution indicates a key physiological shift within feathered dinosaurs" type="journal article" year="2014">
|
||
<superScript attach="left" box="[1053,1060,1303,1316]" fontSize="5" pageId="1" pageNumber="71">5</superScript>
|
||
</bibRefCitation>
|
||
. The membranous tissue contains only small phaeomelanosomes (long axis 300–400 nm), unlike the filamentous feathers in which eumelanosomes predominate and relatively few phaeomelanosomes are present (see Supplementary Information for details).
|
||
</paragraph>
|
||
</subSubSection>
|
||
<caption httpUri="https://zenodo.org/record/2688056/files/figure.png" pageId="1" pageNumber="71" startId="1.[113,172,1346,1365]" targetBox="[117,782,154,1316]" targetPageId="1">
|
||
<paragraph blockId="1.[113,787,1344,1719]" pageId="1" pageNumber="71">
|
||
<emphasis bold="true" box="[113,191,1346,1365]" pageId="1" pageNumber="71">Figure 1</emphasis>
|
||
<emphasis bold="true" box="[197,201,1344,1366]" pageId="1" pageNumber="71">|</emphasis>
|
||
<emphasis bold="true" box="[206,470,1346,1365]" pageId="1" pageNumber="71">
|
||
<taxonomicName box="[206,227,1346,1365]" pageId="1" pageNumber="71">Yi</taxonomicName>
|
||
qi holotype (STM 31-2). a
|
||
</emphasis>
|
||
,
|
||
<emphasis bold="true" box="[480,492,1346,1365]" pageId="1" pageNumber="71">b</emphasis>
|
||
, Photograph (
|
||
<emphasis bold="true" box="[617,627,1346,1365]" pageId="1" pageNumber="71">a</emphasis>
|
||
) and line drawing (
|
||
<emphasis bold="true" box="[121,133,1372,1391]" pageId="1" pageNumber="71">b</emphasis>
|
||
) of specimen;
|
||
<emphasis bold="true" box="[259,268,1372,1391]" pageId="1" pageNumber="71">c</emphasis>
|
||
, skull and mandible in lateral view;
|
||
<emphasis bold="true" box="[580,592,1372,1391]" pageId="1" pageNumber="71">d</emphasis>
|
||
, premaxillary tooth in lateral view;
|
||
<emphasis bold="true" box="[222,231,1397,1416]" pageId="1" pageNumber="71">e</emphasis>
|
||
, left manus;
|
||
<emphasis bold="true" box="[344,351,1397,1416]" pageId="1" pageNumber="71">f</emphasis>
|
||
, styliform elements (the distally unexposed left styliform element articulates with the wrist, and the orientation of the right styliform element implies a similar relationship to the carpus even though its proximal part is missing). Light and dark grey shading indicates feathers and membranous tissues, respectively.an, angular; cv, cervical vertebrae;d, dentary; dr, dorsal ribs;emf,external mandibular fenestra; en, external naris; f, frontal; lf, left femur;lh, left humerus; lmd2–4, left manual digits 2–4; lmt, left metatarsals; lr, left radius; ls, left scapula; lse, left styliform element; lu, left ulna; mb, mandible; mcII–IV, metacarpals II–IV; n, nasal; or, orbit; p, parietal; phII1 to IV4, phalanges II-1 to IV-4; pma, premaxilla; rmd2–4, right manual digits 2–4; rf, right femur; rfi, right fibula; rh, right humerus; rmc, right metacarpals; rmt, right metatarsals; rr, right radius; rse, right styliform element; rt, right tibiotarsus; ru, right ulna; sk, skull. Scale bar, 2 cm.
|
||
</paragraph>
|
||
</caption>
|
||
<subSubSection lastPageId="3" lastPageNumber="73" pageId="1" pageNumber="71" type="discussion">
|
||
<paragraph blockId="1.[816,1490,156,2002]" pageId="1" pageNumber="71">
|
||
A numerical phylogenetic analysis places
|
||
<taxonomicName box="[1255,1277,1448,1469]" pageId="1" pageNumber="71">
|
||
<emphasis box="[1255,1277,1448,1469]" italics="true" pageId="1" pageNumber="71">Yi</emphasis>
|
||
</taxonomicName>
|
||
within the enigmatic
|
||
<taxonomicName authorityName="Czerkas et Yuan" authorityYear="2002" box="[816,1012,1475,1497]" class="Reptilia" family="Scansoriopterygidae" higherTaxonomySource="GBIF,CoL" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="71" phylum="Chordata" rank="family">Scansoriopterygidae</taxonomicName>
|
||
family
|
||
<superScript attach="right" box="[1081,1118,1472,1485]" fontSize="5" pageId="1" pageNumber="71">
|
||
<bibRefCitation author="Zhang, F. & Zhou, Z. & Xu, X. & Wang, X. & Sullivan, C." box="[1081,1096,1472,1485]" journalOrPublisher="Nature" pageId="1" pageNumber="71" pagination="1105 - 1108" part="455" refId="ref3174" refString="14. Zhang, F., Zhou, Z., Xu, X., Wang, X. & Sullivan, C. A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers. Nature 455, 1105 - 1108 (2008)." title="A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers" type="journal article" year="2008">14</bibRefCitation>
|
||
–
|
||
<bibRefCitation author="Czerkas, S. A & Yuan, C. X" box="[1104,1118,1472,1485]" editor="Czerkas, S. J" pageId="1" pageNumber="71" pagination="63 - 95" refId="ref3313" refString="17. Czerkas, S. A. & Yuan, C. X. in Feathered Dinosaurs and the Origin of Flight (ed. Czerkas, S. J.) 63 - 95 (The Dinosaur Museum, 2002)." title="The Dinosaur Museum" type="book" volumeTitle="Feathered Dinosaurs and the Origin of Flight" year="2002">17</bibRefCitation>
|
||
</superScript>
|
||
, which in turn is posited as the sister taxon to other paravians (
|
||
<figureCitation box="[1103,1167,1503,1525]" captionStart="Figure 3" captionStartId="2.[98,157,1728,1747]" captionTargetBox="[120,750,790,1706]" captionTargetId="figure@2.[398,487,1053,1591]" captionTargetPageId="2" captionText="Figure 3 | Simplified coelurosaurian phylogeny showing the recovered position of Yi. The skeletal silhouette and two possible alternative planform reconstructions of Yi highlight the proportionally long and robust forelimbs and large leg feathers that Yi shares with other basal paravian theropods, indicating the presence of aerial capability, and the inferred membranous wings, a feature unique among known paravians but seen in most other gliding or flying tetrapods. Various uncertainties, such as how the styliform element is oriented and whether membranous tissue is present lateral to the trunk as in most volant tetrapods, imply that a variety of reconstructions of the aerodynamic apparatus of Yi are currently plausible (see Supplementary Information for additional possible reconstructions)." httpUri="https://zenodo.org/record/2688066/files/figure.png" pageId="1" pageNumber="71">Fig. 3</figureCitation>
|
||
and Extended Data Fig. 10). Scansoriopterygids including
|
||
<taxonomicName box="[1105,1127,1532,1553]" pageId="1" pageNumber="71">
|
||
<emphasis box="[1105,1127,1532,1553]" italics="true" pageId="1" pageNumber="71">Yi</emphasis>
|
||
</taxonomicName>
|
||
have numerous unusual skeletal features, including a highly elongated third finger and a highly modified pelvis
|
||
<superScript attach="right" box="[872,923,1584,1597]" fontSize="5" pageId="1" pageNumber="71">
|
||
<bibRefCitation author="Zhang, F. & Zhou, Z. & Xu, X. & Wang, X. & Sullivan, C." box="[872,888,1584,1597]" journalOrPublisher="Nature" pageId="1" pageNumber="71" pagination="1105 - 1108" part="455" refId="ref3174" refString="14. Zhang, F., Zhou, Z., Xu, X., Wang, X. & Sullivan, C. A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers. Nature 455, 1105 - 1108 (2008)." title="A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers" type="journal article" year="2008">14</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Zhang, F. & Zhou, Z. & Xu, X. & Wang, X." box="[890,906,1584,1597]" journalOrPublisher="Naturwissenschaften" pageId="1" pageNumber="71" pagination="394 - 398" part="89" refId="ref3272" refString="16. Zhang, F., Zhou, Z., Xu, X. & Wang, X. A juvenile coelurosaurian theropod from China indicates arboreal habits. Naturwissenschaften 89, 394 - 398 (2002)." title="A juvenile coelurosaurian theropod from China indicates arboreal habits" type="journal article" year="2002">16</bibRefCitation>
|
||
,
|
||
<bibRefCitation author="Czerkas, S. A & Yuan, C. X" box="[908,923,1584,1597]" editor="Czerkas, S. J" pageId="1" pageNumber="71" pagination="63 - 95" refId="ref3313" refString="17. Czerkas, S. A. & Yuan, C. X. in Feathered Dinosaurs and the Origin of Flight (ed. Czerkas, S. J.) 63 - 95 (The Dinosaur Museum, 2002)." title="The Dinosaur Museum" type="book" volumeTitle="Feathered Dinosaurs and the Origin of Flight" year="2002">17</bibRefCitation>
|
||
</superScript>
|
||
. They also display unusual integumentary features: despite being basal paravians, they lack pinnate feathers, but their filamentous feathers resemble the pinnate feathers of other pennaraptorans in having morphologically diverse melanosomes
|
||
<bibRefCitation author="Li, Q." box="[1254,1261,1668,1681]" journalOrPublisher="Nature" pageId="1" pageNumber="71" pagination="350 - 353" part="507" refId="ref2826" refString="5. Li, Q. et al. Melanosome evolution indicates a key physiological shift within feathered dinosaurs. Nature 507, 350 - 353 (2014)." title="Melanosome evolution indicates a key physiological shift within feathered dinosaurs" type="journal article" year="2014">
|
||
<superScript attach="left" box="[1254,1261,1668,1681]" fontSize="5" pageId="1" pageNumber="71">5</superScript>
|
||
</bibRefCitation>
|
||
. Given that scansoriopterygids are phylogenetically nested within Pennaraptora, they appear to represent a case of extreme morphological divergence near the origin of birds, involving not only extensive modification of the skeleton but also secondary loss of normal pennaraptoran pinnate feathers.
|
||
</paragraph>
|
||
<paragraph blockId="1.[816,1490,156,2002]" lastBlockId="2.[801,1475,778,2002]" lastPageId="2" lastPageNumber="72" pageId="1" pageNumber="71">
|
||
Large flight feathers and even propatagia are present in the basal oviraptorosaur
|
||
<taxonomicName box="[964,1083,1868,1889]" class="Reptilia" family="Caudipterygidae" genus="Caudipteryx" higherTaxonomySource="GBIF,CoL" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="71" phylum="Chordata" rank="genus">
|
||
<emphasis box="[964,1083,1868,1889]" italics="true" pageId="1" pageNumber="71">Caudipteryx</emphasis>
|
||
</taxonomicName>
|
||
and the basal deinonychosaurs
|
||
<taxonomicName box="[1384,1490,1868,1889]" class="Reptilia" family="Not" genus="Anchiornis" higherTaxonomySource="CoL" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="71" phylum="Chordata" rank="genus">
|
||
<emphasis box="[1384,1490,1868,1889]" italics="true" pageId="1" pageNumber="71">Anchiornis</emphasis>
|
||
</taxonomicName>
|
||
and
|
||
<taxonomicName box="[863,981,1896,1917]" class="Reptilia" family="Dromaeosauridae" genus="Microraptor" higherTaxonomySource="GBIF,CoL" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="71" phylum="Chordata" rank="genus">
|
||
<emphasis box="[863,981,1896,1917]" italics="true" pageId="1" pageNumber="71">Microraptor</emphasis>
|
||
</taxonomicName>
|
||
<superScript attach="left" box="[981,1005,1893,1906]" fontSize="5" pageId="1" pageNumber="71">
|
||
<bibRefCitation author="Ji, Q. & Currie, P. J. & Norell, M. A. & Ji, S. - A." box="[981,987,1893,1906]" journalOrPublisher="Nature" pageId="1" pageNumber="71" pagination="753 - 761" part="393" refId="ref2679" refString="1. Ji, Q., Currie, P. J., Norell, M. A. & Ji, S. - A. Two feathered dinosaurs from northeastern China. Nature 393, 753 - 761 (1998)." title="Two feathered dinosaurs from northeastern China" type="journal article" year="1998">1</bibRefCitation>
|
||
–
|
||
<bibRefCitation author="Hu, D. & Hou, L. & Zhang, L. & Xu, X." box="[997,1005,1893,1906]" journalOrPublisher="Nature" pageId="1" pageNumber="71" pagination="640 - 643" part="461" refId="ref2748" refString="3. Hu, D., Hou, L., Zhang, L. & Xu, X. A pre- Archaeopteryx troodontid from China with long feathers on the metatarsus. Nature 461, 640 - 643 (2009)." title="A pre- Archaeopteryx troodontid from China with long feathers on the metatarsus" type="journal article" year="2009">3</bibRefCitation>
|
||
</superScript>
|
||
(and a propatagium has been identified in the scansoriopterygid
|
||
<taxonomicName box="[999,1161,1924,1945]" class="Reptilia" family="Not" genus="Epidendrosaurus" higherTaxonomySource="CoL" kingdom="Animalia" order="Dinosauria" pageId="1" pageNumber="71" phylum="Chordata" rank="genus">
|
||
<emphasis box="[999,1161,1924,1945]" italics="true" pageId="1" pageNumber="71">Epidendrosaurus</emphasis>
|
||
</taxonomicName>
|
||
<bibRefCitation author="Czerkas, S. A. & Feduccia, A" box="[1162,1177,1921,1934]" journalOrPublisher="J. Ornithol" pageId="1" pageNumber="71" pagination="841 - 851" part="155" refId="ref3492" refString="22. Czerkas, S. A. & Feduccia, A. Jurassic archosaur is a non-dinosaurian bird. J. Ornithol. 155, 841 - 851 (2014)." title="Jurassic archosaur is a non-dinosaurian bird" type="book" year="2014">
|
||
<superScript attach="right" box="[1162,1177,1921,1934]" fontSize="5" pageId="1" pageNumber="71">22</superScript>
|
||
</bibRefCitation>
|
||
), indicating that the feathered wing is a primitive feature of the Pennaraptora even though basal members of this group are flightless
|
||
<bibRefCitation author="Foth, C. & Tischlinger, H. & Rauhut, O. W. M." box="[1163,1178,1977,1990]" journalOrPublisher="Nature" pageId="1" pageNumber="71" pagination="79 - 82" part="511" refId="ref3525" refString="23. Foth, C., Tischlinger, H. & Rauhut, O. W. M. New specimen of Archaeopteryx provides insights into the evolution of pennaceous feathers. Nature 511, 79 - 82 (2014)." title="New specimen of Archaeopteryx provides insights into the evolution of pennaceous feathers" type="journal article" year="2014">
|
||
<superScript attach="left" box="[1163,1178,1977,1990]" fontSize="5" pageId="1" pageNumber="71">23</superScript>
|
||
</bibRefCitation>
|
||
. Both phylogenetic bracketing
|
||
<bibRefCitation author="Witmer, L. M." box="[1474,1489,1977,1990]" editor="Thomason, J. J." journalOrPublisher="Cambridge Univ. Press" pageId="1" pageNumber="71" pagination="19 - 33" refId="ref3568" refString="24. Witmer, L. M. in Functional Morphology in Vertebrate Paleontology (ed. Thomason, J. J.) 19 - 33 (Cambridge Univ. Press, 1995)." type="book chapter" volumeTitle="Functional Morphology in Vertebrate Paleontology" year="1995">
|
||
<superScript attach="left" box="[1474,1489,1977,1990]" fontSize="5" pageId="1" pageNumber="71">24</superScript>
|
||
</bibRefCitation>
|
||
and the preserved morphology of the shoulder girdle and forelimb suggest that
|
||
<taxonomicName box="[923,945,807,828]" pageId="2" pageNumber="72">
|
||
<emphasis box="[923,945,807,828]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
resembles other basal paravians in the overall skeletal structure of its thoracic girdle and appendages. In
|
||
<taxonomicName box="[1311,1332,834,855]" pageId="2" pageNumber="72">
|
||
<emphasis box="[1311,1332,834,855]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
, however, the large flight feathers present in other pennaraptorans appear to be at least partly replaced by membranes supported by the styliform element and manual digits, in stark contrast to the archetypal wings that are universal in birds and their closest relatives. The highly elongated manual digit IV of
|
||
<taxonomicName box="[991,1013,974,995]" pageId="2" pageNumber="72">
|
||
<emphasis box="[991,1013,974,995]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
and other scansoriopterygids is unique among theropods but superficially similar to the long manual digits II–V of bats and the highly elongated fourth finger in pterosaurs. Furthermore, some major components of the wing of
|
||
<taxonomicName box="[1184,1205,1058,1079]" pageId="2" pageNumber="72">
|
||
<emphasis box="[1184,1205,1058,1079]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
, such as the membrane and styliform element, are not known in other winged theropods. The discovery of
|
||
<taxonomicName box="[923,945,1113,1134]" pageId="2" pageNumber="72">
|
||
<emphasis box="[923,945,1113,1134]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
thus adds considerably to the known diversity of thoracic appendage morphologies present near the transition to birds.
|
||
</paragraph>
|
||
<caption httpUri="https://zenodo.org/record/2688060/files/figure.png" pageId="2" pageNumber="72" targetBox="[98,1004,160,720]" targetPageId="2">
|
||
<paragraph blockId="2.[1042,1478,143,366]" pageId="2" pageNumber="72">
|
||
<emphasis bold="true" box="[1042,1119,145,164]" pageId="2" pageNumber="72">
|
||
Figure
|
||
<pageNumber ambiguity="1" box="[1108,1119,145,164]" fuzzyness="0" pageId="2" pageNumber="72" score="2.0" value="2">2</pageNumber>
|
||
</emphasis>
|
||
<emphasis bold="true" box="[1126,1130,143,165]" pageId="2" pageNumber="72">|</emphasis>
|
||
<emphasis bold="true" pageId="2" pageNumber="72">
|
||
Soft tissues preserved in
|
||
<taxonomicName box="[1352,1373,145,164]" pageId="2" pageNumber="72">Yi</taxonomicName>
|
||
qi holotype (STM 31-2). a–e
|
||
</emphasis>
|
||
, Feathers above the skull
|
||
</paragraph>
|
||
<paragraph blockId="2.[1042,1478,143,366]" pageId="2" pageNumber="72">
|
||
(
|
||
<emphasis bold="true" box="[1050,1060,196,215]" pageId="2" pageNumber="72">a</emphasis>
|
||
), along the humerus (
|
||
<emphasis bold="true" box="[1246,1258,196,215]" pageId="2" pageNumber="72">b</emphasis>
|
||
) and along the tibiotarsus (
|
||
<emphasis bold="true" box="[1050,1059,221,240]" pageId="2" pageNumber="72">c</emphasis>
|
||
); isolated basally converging (
|
||
<emphasis bold="true" box="[1322,1334,221,240]" pageId="2" pageNumber="72">d</emphasis>
|
||
) and brush-like (
|
||
<emphasis bold="true" box="[1050,1059,246,265]" pageId="2" pageNumber="72">e</emphasis>
|
||
) feathers;
|
||
<emphasis bold="true" box="[1150,1157,246,265]" pageId="2" pageNumber="72">f</emphasis>
|
||
, sheet-like soft tissue associated with the right forelimb (yellow arrows point to patches of sheet-like soft tissue);
|
||
<emphasis bold="true" box="[1249,1260,297,316]" pageId="2" pageNumber="72">g</emphasis>
|
||
, comparison of sheet-like soft tissue (above digit II) and individual feathers (below digit II).
|
||
</paragraph>
|
||
</caption>
|
||
<paragraph blockId="2.[801,1475,778,2002]" pageId="2" pageNumber="72">
|
||
Because other amniotes that possess a styliform element invariably utilize this structure to support an aerodynamic membrane that contributes to gliding or powered flight
|
||
<superScript attach="left" box="[1143,1174,1223,1236]" fontSize="5" pageId="2" pageNumber="72">
|
||
<bibRefCitation author="Schutt, W. A. Jr & Simmons, N. B." box="[1143,1150,1223,1236]" journalOrPublisher="J. Mamm. Evol." pageId="2" pageNumber="72" pagination="1 - 32" part="5" refId="ref2856" refString="6. Schutt, W. A. Jr & Simmons, N. B. Morphology and homology of the chiropteran calcar, with comments on the phylogenetic relationships of Archaeopteropus. J. Mamm. Evol. 5, 1 - 32 (1998)." title="Morphology and homology of the chiropteran calcar, with comments on the phylogenetic relationships of Archaeopteropus" type="journal article" year="1998">6</bibRefCitation>
|
||
–
|
||
<bibRefCitation author="Simmons, N. B. & Seymour, K. L. & Habersetzer, J. & Gunnell, G. F." box="[1159,1174,1223,1236]" journalOrPublisher="Nature" pageId="2" pageNumber="72" pagination="818 - 821" part="451" refId="ref3013" refString="10. Simmons, N. B., Seymour, K. L., Habersetzer, J. & Gunnell, G. F. Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation. Nature 451, 818 - 821 (2008)." title="Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation" type="journal article" year="2008">10</bibRefCitation>
|
||
</superScript>
|
||
, and alternative functions for a long, unjointed rod of bone or cartilage extending from a distal limb joint are difficult to imagine (see Supplementary Information), the occurrence of a styliform element in
|
||
<taxonomicName box="[1180,1202,1310,1331]" pageId="2" pageNumber="72">
|
||
<emphasis box="[1180,1202,1310,1331]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
is a strong indication that membranous aerodynamic surfaces and some degree of aerial capability were present in this taxon. Further evidence that
|
||
<taxonomicName box="[1337,1359,1366,1387]" pageId="2" pageNumber="72">
|
||
<emphasis box="[1337,1359,1366,1387]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
was volant comes from the preserved patches of membranous tissue associated with the styliform element and digits, and from the proportions of the appendicular skeleton (see Supplementary Information). It is worth emphasizing that, even if our inference that
|
||
<taxonomicName box="[1224,1246,1477,1498]" pageId="2" pageNumber="72">
|
||
<emphasis box="[1224,1246,1477,1498]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
was an aerially adapted taxon with membranous wings proves incorrect, the styliform element and membranous tissue patches will stand as highly unusual features that imply some kind of equally distinctive forelimb function in this peculiar theropod.
|
||
</paragraph>
|
||
<paragraph blockId="2.[801,1475,778,2002]" lastBlockId="3.[113,787,155,679]" lastPageId="3" lastPageNumber="73" pageId="2" pageNumber="72">
|
||
Even under our preferred interpretation, the flight apparatus of
|
||
<taxonomicName box="[1453,1475,1618,1639]" pageId="2" pageNumber="72">
|
||
<emphasis box="[1453,1475,1618,1639]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
cannot be confidently reconstructed due to the incomplete preservation of the wing membrane in the only known specimen, combined with uncertainties regarding the styliform element’s orientation and connection to the wrist. However, the range of possible flight apparatus configurations can be explored by considering different reconstructions (
|
||
<figureCitation box="[863,918,1784,1806]" captionStart="Figure 3" captionStartId="2.[98,157,1728,1747]" captionTargetBox="[120,750,790,1706]" captionTargetId="figure@2.[398,487,1053,1591]" captionTargetPageId="2" captionText="Figure 3 | Simplified coelurosaurian phylogeny showing the recovered position of Yi. The skeletal silhouette and two possible alternative planform reconstructions of Yi highlight the proportionally long and robust forelimbs and large leg feathers that Yi shares with other basal paravian theropods, indicating the presence of aerial capability, and the inferred membranous wings, a feature unique among known paravians but seen in most other gliding or flying tetrapods. Various uncertainties, such as how the styliform element is oriented and whether membranous tissue is present lateral to the trunk as in most volant tetrapods, imply that a variety of reconstructions of the aerodynamic apparatus of Yi are currently plausible (see Supplementary Information for additional possible reconstructions)." httpUri="https://zenodo.org/record/2688066/files/figure.png" pageId="2" pageNumber="72">Fig. 3</figureCitation>
|
||
and Extended Data
|
||
<figureCitation box="[1120,1175,1784,1806]" captionStart="Extended" captionStartId="10.[98,183,1191,1210]" captionTargetBox="[225,1350,151,1169]" captionTargetId="figure@10.[220,1353,151,1175]" captionTargetPageId="10" captionText="Extended Data Figure 7 | Aerodynamic apparatuses in Yi and other tetrapods. a–c, Wing of Yi, Bat Model (a), Maniraptoran Model (b), and Frog Model (c); d, bat wing; e, pigeon wing; f, pterosaur wing; g, giant Japanese flying squirrel wing. Yellow colour indicates styliform element in a, b, c, d, f, and g." httpUri="https://zenodo.org/record/2688088/files/figure.png" pageId="2" pageNumber="72">Fig. 7</figureCitation>
|
||
) that are supported to varying degrees by morphological and taphonomic information from the specimen, fundamental aerodynamic principles, and the aerial locomotion of other volant tetrapods. Preliminary analysis of the wing loadings and other properties of some of these configurations supports the plausibility of
|
||
<taxonomicName box="[1012,1034,1925,1946]" pageId="2" pageNumber="72">
|
||
<emphasis box="[1012,1034,1925,1946]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
as a volant taxon (see Supplementary Information). In having wings with a well-developed membranous component,
|
||
<taxonomicName box="[923,945,1980,2001]" pageId="2" pageNumber="72">
|
||
<emphasis box="[923,945,1980,2001]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
would differ from other volant paravians but resemble distantly related groups including pterosaurs, bats and many gliding mammals, representing a striking case of convergent evolution of the aerodynamic apparatus among tetrapods
|
||
<superScript attach="left" box="[513,544,208,221]" fontSize="5" pageId="3" pageNumber="73">
|
||
<bibRefCitation author="Schutt, W. A. Jr & Simmons, N. B." box="[513,520,208,221]" journalOrPublisher="J. Mamm. Evol." pageId="3" pageNumber="73" pagination="1 - 32" part="5" refId="ref2856" refString="6. Schutt, W. A. Jr & Simmons, N. B. Morphology and homology of the chiropteran calcar, with comments on the phylogenetic relationships of Archaeopteropus. J. Mamm. Evol. 5, 1 - 32 (1998)." title="Morphology and homology of the chiropteran calcar, with comments on the phylogenetic relationships of Archaeopteropus" type="journal article" year="1998">6</bibRefCitation>
|
||
–
|
||
<bibRefCitation author="Simmons, N. B. & Seymour, K. L. & Habersetzer, J. & Gunnell, G. F." box="[529,544,208,221]" journalOrPublisher="Nature" pageId="3" pageNumber="73" pagination="818 - 821" part="451" refId="ref3013" refString="10. Simmons, N. B., Seymour, K. L., Habersetzer, J. & Gunnell, G. F. Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation. Nature 451, 818 - 821 (2008)." title="Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation" type="journal article" year="2008">
|
||
<pageNumber ambiguity="1" box="[529,544,208,221]" fuzzyness="0" pageId="3" pageNumber="73" score="3.0" value="10">10</pageNumber>
|
||
</bibRefCitation>
|
||
</superScript>
|
||
.
|
||
</paragraph>
|
||
<caption httpUri="https://zenodo.org/record/2688066/files/figure.png" pageId="2" pageNumber="72" startId="2.[98,157,1728,1747]" targetBox="[120,750,790,1706]" targetPageId="2">
|
||
<paragraph blockId="2.[98,771,1726,1999]" pageId="2" pageNumber="72">
|
||
<emphasis bold="true" box="[98,175,1728,1747]" pageId="2" pageNumber="72">Figure 3</emphasis>
|
||
<emphasis bold="true" box="[182,186,1726,1748]" pageId="2" pageNumber="72">|</emphasis>
|
||
<emphasis bold="true" pageId="2" pageNumber="72">
|
||
Simplified coelurosaurian phylogeny showing the recovered position of
|
||
<taxonomicName box="[203,225,1753,1772]" pageId="2" pageNumber="72">Yi</taxonomicName>
|
||
.
|
||
</emphasis>
|
||
The skeletal silhouette and two possible alternative planform reconstructions of
|
||
<taxonomicName box="[261,280,1779,1797]" pageId="2" pageNumber="72">
|
||
<emphasis box="[261,280,1779,1797]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
highlight the proportionally long and robust forelimbs and large leg feathers that
|
||
<taxonomicName box="[328,347,1804,1822]" pageId="2" pageNumber="72">
|
||
<emphasis box="[328,347,1804,1822]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
shares with other basal paravian theropods, indicating the presence of aerial capability, and the inferred membranous wings, a feature unique among known paravians but seen in most other gliding or flying tetrapods. Various uncertainties, such as how the styliform element is oriented and whether membranous tissue is present lateral to the trunk as in most volant tetrapods, imply that a variety of reconstructions of the aerodynamic apparatus of
|
||
<taxonomicName box="[330,349,1956,1974]" pageId="2" pageNumber="72">
|
||
<emphasis box="[330,349,1956,1974]" italics="true" pageId="2" pageNumber="72">Yi</emphasis>
|
||
</taxonomicName>
|
||
are currently plausible (see Supplementary Information for additional possible reconstructions).
|
||
</paragraph>
|
||
</caption>
|
||
<paragraph blockId="3.[113,787,155,679]" pageId="3" pageNumber="73">
|
||
The mode of aerial locomotion that might have been used by
|
||
<taxonomicName box="[743,765,240,261]" pageId="3" pageNumber="73">
|
||
<emphasis box="[743,765,240,261]" italics="true" pageId="3" pageNumber="73">Yi</emphasis>
|
||
</taxonomicName>
|
||
is difficult to reconstruct on the basis of present evidence.
|
||
<taxonomicName box="[664,686,268,289]" pageId="3" pageNumber="73">
|
||
<emphasis box="[664,686,268,289]" italics="true" pageId="3" pageNumber="73">Yi</emphasis>
|
||
</taxonomicName>
|
||
may have been capable of flapping flight or only of gliding, or may have combined the two locomotor styles as in many extant birds and some bats (see Supplementary Information). There are some indications that
|
||
<taxonomicName box="[765,787,351,372]" pageId="3" pageNumber="73">
|
||
<emphasis box="[765,787,351,372]" italics="true" pageId="3" pageNumber="73">Yi</emphasis>
|
||
</taxonomicName>
|
||
may have relied more on gliding than on flapping, including the lack of strongly expanded muscle attachment surfaces on the forelimb bones and the possibility that the unwieldy styliform element would have interfered with the rapid oscillations and rotations of the distal part of the forelimb needed for efficient flapping flight, but the mode of aerial locomotion that is most likely for
|
||
<taxonomicName box="[433,455,519,540]" pageId="3" pageNumber="73">
|
||
<emphasis box="[433,455,519,540]" italics="true" pageId="3" pageNumber="73">Yi</emphasis>
|
||
</taxonomicName>
|
||
remains uncertain. Regardless, the evident occurrence in this taxon of a membranous wing supported by a styliform element represents an unexpected aerodynamic innovation close to the origin of birds, and highlights the breadth of flight-related morphological experimentation that took place in the early stages of paravian history.
|
||
</paragraph>
|
||
</subSubSection>
|
||
</treatment>
|
||
</document> |