Revisiting a long-overlooked skull: Implications for the distribution of Dinodontosaurus brevirostris (Kannemeyeriiformes) in the Brazilian Triassic.

Abstract

Dicynodonts (Anomodontia: Dicynodontia) were one of the main groups of terrestrial tetrapods in Permian and Triassic faunas. In Brazil, the genus Dinodontosaurus is one of the most common tetrapod taxon in the Triassic Santa Maria Supersequence. This genus has a complex taxonomic history and is represented in the Triassic of both Argentina and Brazil. Nevertheless, only the species Dinodontosaurus tener is currently recognized as being present in Brazil. Dinodontosaurus tener exhibits high morphological variability among known specimens, partly due to taphonomic alterations but also potentially reflecting intraspecific or even interspecific variation. This study evaluates the morphology and taxonomic assignment of specimen MCP-1645-PV, a relatively well-preserved skull whose morphology was briefly described in the 1980s and at that time attributed to the genus Chanaria. Currently, Chanaria platyceps is considered synonymous with Dinodontosaurus brevirostris, a species regarded as endemic to Argentina. In this contribution, we reassess the morphology of specimen MCP-1645-PV and its possible classification as Dinodontosaurus brevirostris, in light of recent advances in the understanding of Dinodontosaurus taxonomy. Based on anatomical and morphometric comparisons, our study indicates the presence of Dinodontosaurus brevirostris in the Brazilian Triassic, highlighting the need for a critical reassessment of historical specimens.