A reassessment of the species “Podocnemis” brasiliensis (Pleurodira, Pelomedusoides) from the Late Cretaceous Bauru Group

Abstract The Bauru Group of the Paraná Basin (Upper Cretaceous) has yielded a rich assemblage of fossil turtles, with nine formally named species. However, many of the taxa described for this unit are poorly known, being considered nomina dubia by most authors. One such taxon is “ Podocnemis ” brasiliensis , described in the 1930’s and known only from its lectotype, a fragmentary plastron. In this paper we present new turtle remains that are attributable to “ P. ” brasiliensis , preserving parts of the plastron that were lacking in the lectotype. This novel anatomical information has permitted us to emend the diagnosis of “ P. ” brasiliensis and recognize it as a valid species of Pan-Podocnemididae, although its phylogenetic position within that clade is still unsettled. Fragmentary specimens that had been attributed to “ P. ” brasiliensis in the past were revised, and we concluded they cannot be confidently assigned to this taxon. We also analyzed variation in average shell thickness among podocnemidoids, to evaluate whether this variation was correlated with taxonomic distinctions. Though we could not estimate the average shell thickness for “ P. ” brasiliensis , our results demonstrate that the species Bauruemys elegans has a relatively thinner shell in comparison to other South American podocnemidoids.