A new short-faced archosauriform from the Upper Triassic Placerias/Downs' quarry complex, Arizona, USA, expands the morphological diversity of the Triassic archosauriform radiation

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dc.contributor.authorHeckert, Andrew B.en
dc.contributor.authorNesbitt, Sterling J.en
dc.contributor.authorStocker, Michelle R.en
dc.contributor.authorSchneider, Vincent P.en
dc.contributor.authorHoffman, Devin K.en
dc.contributor.authorZimmer, Brian W.en
dc.contributor.departmentGeosciencesen
dc.coverage.stateArizonaen
dc.date.accessioned2021-07-20T18:48:06Zen
dc.date.available2021-07-20T18:48:06Zen
dc.date.issued2021-08en
dc.description.abstractThe Placerias/Downs' Quarry complex in eastern Arizona, USA, is the most diverse Upper Triassic vertebrate locality known. We report a new short-faced archosauriform, Syntomiprosopus sucherorum gen. et sp. nov., represented by four incomplete mandibles, that expands that diversity with a morphology unique among Late Triassic archosauriforms. The most distinctive feature of Syntomiprosopus gen. nov. is its anteroposteriorly short, robust mandible with 3-4 anterior, a larger caniniform, and 1-3 "postcanine" alveoli. The size and shape of the alveoli and the preserved tips of replacement teeth preclude assignment to any taxon known only from teeth. Additional autapomorphies of S. sucherorum gen. et sp. nov. include a large fossa associated with the mandibular fenestra, an interdigitating suture of the surangular with the dentary, fine texture ornamenting the medial surface of the splenial, and a surangular ridge that completes a 90 degrees arc. The external surfaces of the mandibles bear shallow, densely packed, irregular, fine pits and narrow, arcuate grooves. This combination of character states allows an archosauriform assignment; however, an associated and similarly sized braincase indicates that Syntomiprosopus n. gen. may represent previously unsampled disparity in early-diverging crocodylomorphs. The Placerias Quarry is Adamanian (Norian, maximum depositional age similar to 219 Ma), and this specimen appears to be an early example of shortening of the skull, which occurs later in diverse archosaur lineages, including the Late Cretaceous crocodyliform Simosuchus. This is another case where Triassic archosauriforms occupied morphospace converged upon by other archosaurs later in the Mesozoic and further demonstrates that even well-sampled localities can yield new taxa.en
dc.description.notesFunding to support open access publication of this contribution was provided by the Department of Geological Sciences, the College of Arts and Sciences, and the Honors College at Appalachian State University.en
dc.description.sponsorshipDepartment of Geological Sciences at Appalachian State University; College of Arts and Sciences at Appalachian State University; Honors College at Appalachian State Universityen
dc.description.versionPublished versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.doihttps://doi.org/10.1007/s00114-021-01733-1en
dc.identifier.eissn1432-1904en
dc.identifier.issn0028-1042en
dc.identifier.issue4en
dc.identifier.other32en
dc.identifier.pmid34213630en
dc.identifier.urihttp://hdl.handle.net/10919/104229en
dc.identifier.volume108en
dc.language.isoenen
dc.rightsCreative Commons Attribution 4.0 Internationalen
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.subjectCrocodylomorphaen
dc.subjectConvergent evolutionen
dc.subjectNorianen
dc.subjectJawen
dc.subjectDiversityen
dc.subjectArchosauriformesen
dc.titleA new short-faced archosauriform from the Upper Triassic Placerias/Downs' quarry complex, Arizona, USA, expands the morphological diversity of the Triassic archosauriform radiationen
dc.title.serialScience of Natureen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten
dc.type.dcmitypeStillImageen

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