Computed tomographic analysis of the cranium of the early Permian recumbirostran ‘microsaur’ Euryodus dalyae reveals new details of the braincase and mandible

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dc.contributor.authorGee, BMen_AU
dc.contributor.authorBevitt, JJen_AU
dc.contributor.authorReisz, RRen_AU
dc.date.accessioned2024-10-03T06:35:55Zen_AU
dc.date.available2024-10-03T06:35:55Zen_AU
dc.date.issued2021-05-12en_AU
dc.date.statistics2024-10-03en_AU
dc.description.abstractRecumbirostran ‘microsaurs’ are a clade of Palaeozoic tetrapods that possess numerous morphological adaptations for fossorial ecologies. Re‐study of many ‘microsaurs’ using tomographic methods has provided substantial new data on poorly known anatomy that informs their debated phylogenetic position. Recent studies have identified suites of features among recumbirostrans that place the group within crown Amniota, contrary to hypothesized positions on the amniote stem or the lissamphibian stem. Herein we describe the cranial anatomy of the early Permian gymnarthrid Euryodus dalyae through tomographic analysis of the holotype from South Grandfield, Oklahoma and new specimens from karst deposits near Richards Spur. The braincase of E. dalyae is composed of well‐ossified pleurosphenoids, orbitosphenoids that brace against the skull roof, and unpaired median ossifications. The otic capsules are well‐ossified, and the occiput is unconsolidated. Analysis of the mandibles, typically obscured in articulated specimens, reveals a second tooth row on the dentary, a feature previously unknown in ‘microsaurs’ that is reminiscent of the condition of the co‐occurring captorhinid Captorhinus aguti. The Richards Spur specimens share many of these features, including the second tooth row, but the neurocranium of the scanned specimen (OMNH 53519) differs from that of the holotype of E. dalyae (e.g. absence of unpaired median ossifications), and these specimens are referred to Euryodus sp. These data add to the growing neurocranial dataset of ‘microsaurs’, which is essential for iterative reevaluation of early tetrapod phylogeny. This discovery of multiple tooth rows in ‘microsaurs’ provides further support for the hypothesized close relationships between ‘microsaurs’ and reptiles. © 1999-2024 John Wiley & Sons, Incen_AU
dc.description.sponsorshipWe thank Bill May, Rich Cifelli, Jennifer Larsen, and their colleagues at the OMNH for their support of our work on the Richards Spur locality and to Zhe-Xi Luo and April Neander for scanning FM UR 2296. We also thank Diane Scott for photographs used in Figures 1, 2 and 7, 8 and Supplementary Figures 4–6. Thanks to Jason Pardo, Arjan Mann, and Yara Haridy for discussion. Thanks to Jennifer Olori, an anonymous reviewer, and the editor, Marcello Ruta, for constructive feedback that greatly improved this manuscript. This research was supported by grants from the University of Toronto and the Natural Sciences and Engineering Research Council of Canada (NSERC) to RRR and an Ontario Graduate Scholarship (OGS) to BMG. The authors declare that there are no conflicts of interest.en_AU
dc.identifier.citationGee, B. M., Bevitt, J. J., & Reisz, R. R. (2021). Computed tomographic analysis of the cranium of the early Permian recumbirostran ‘microsaur’ Euryodus dalyae reveals new details of the braincase and mandible. Papers in Palaeontology, 7(2), 721-749. doi:0.1002/spp2.1304en_AU
dc.identifier.issn2056-2799en_AU
dc.identifier.issn2056-2802en_AU
dc.identifier.issue2en_AU
dc.identifier.journaltitlePapers in Palaeontologyen_AU
dc.identifier.pagination721-749en_AU
dc.identifier.urihttp://dx.doi.org/10.1002/spp2.1304en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15707en_AU
dc.identifier.volume7en_AU
dc.languageEnglishen_AU
dc.language.isoenen_AU
dc.publisherWileyen_AU
dc.subjectProton computed tomographyen_AU
dc.subjectFossilsen_AU
dc.subjectEcologyen_AU
dc.subjectSkullen_AU
dc.subjectTeethen_AU
dc.subjectDataen_AU
dc.subjectArchaeological specimensen_AU
dc.titleComputed tomographic analysis of the cranium of the early Permian recumbirostran ‘microsaur’ Euryodus dalyae reveals new details of the braincase and mandibleen_AU
dc.typeJournal Articleen_AU
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