Brazilian Permian dvinosaurs (Amphibia, Temnospondyli): revised description and phylogeny

ABSTRACT

Recently collected temnospondyl fossils from the Cisuralian Pedra de Fogo Formation (north-eastern Brazil) indicate a diverse assemblage of aquatic tetrapods, including the dvinosaurs Timonya anneae and Procuhy nazariensis. Here we present revised diagnoses for these species and detailed descriptions of their holotypes. Timonya anneae is distinguished from all other dvinosaurs by several cranial characters including: combined width of both parietals less than interorbital width; presence of a groove-like internal carotid artery foramen; and presence of an ossified opisthotic. In the mandible, T. anneae presents two parasymphyseal fossae on each side of the mandibular symphysis to accommodate palatal fangs and a well-developed postglenoid area. Procuhy nazariensis, mostly preserved as a mold of the skull table and mandible, is diagnosed by the presence of the anteriormost extension of the squamosal posterior to parietal midlength; pineal foramen posterior to the midlength of the parietal; supratemporal exposed on the posterior border of the skull table; and presence of postglenoid process of the surangular separated from the retroarticular process of the articular by the mandibular sulcus. A new inclusive phylogeny of Temnospondyli indicates that Dvinosauria consists of the Trimerorhachidae (including Procuhy as the sister-taxon of Trimerorhachis) and the ‘short-snouted’ dvinosaurs, with Timonya as an early-diverging representative of the latter clade. The Pedra de Fogo dvinosaurs show close relationships with Cisuralian taxa from the North American southwest, reinforcing close paleogeographic connections between these regions in the late Paleozoic, but represent endemic taxa, corroborating the pattern suggested by the plant fossil record.

ACKNOWLEDGEMENTS

Research was supported by grants from The Negaunee Foundation, The Grainger Foundation, the Field Museum of Natural History, Conselho Nacional para a Ciencia e Tecnologia (CNPq 401848.2010-8, 456608/2014-1), National Geographic Committee for Research and Exploration (9601-14), Universidad de Buenos Aires Ciencia y Técnica (UBACyT 20020170100643), Sofja Kovalevskaja Award of the Alexander von Humboldt Foundation, and the Natural History Museum of London. We thank S. Bessone and S. Gibson for preparation of the delicate Timonya specimens, A. Shinya for additional fossil preparation, B. Smith (Varian Medical Systems) for CT-scanning assistance, and R. Sadleir for assistance with processing the CT data. We thank the editor A. Huttenlocker and E. V. Dias and T. Arbez for their constructive reviews. This is CAM’s contribution R-345 to the Instituto de Estudios Andinos Don Pablo Groeber.