New records of Testudines from the Presidente Prudente Formation of the Bauru Group (Late Cretaceous), with a revised diagnosis for Roxochelys wanderleyi and palaeoichnological remarks

Abstract

Fossils of Testudines from the Cretaceous Bauru Group in Brazil have been known since the beginning of the last century. However, our knowledge about them is still limited. In this contribution, we describe new turtle remains from the Late Cretaceous Presidente Prudente Formation, collected in two relatively underexplored municipalities in the western part of the state of São Paulo. Studied material includes isolated remains of indeterminate Testudines, shell fragments identified as cf. Roxochelys and a moderately complete plastron of Roxochelys wanderleyi. The new Roxochelys material allowed us to provide an emended diagnosis for this taxon, correcting inadequate aspects of past diagnoses and providing a new morphological trait for the identification of this genus. Bioerosive features on the outer surface of the sampled turtle remains are described and discussed, including traces attributable to the ichnogenera Gunnellichnus, Karethraichnus, Thatchtelithichnus and Violinichnus. This new record represents an expansion of the geographic range of these ichnotaxa, and a unique record for the Mesozoic of the Southern Hemisphere.