New records of fossil vertebrates from the upper cretaceous adamantina formation (Bauru group), southeastern Brazil

Abstract

The Adamantina Formation (Bauru Group), between Lucélia and Irapuru municipalities (northwestern São Paulo State, southeastern Brazil), has been in the last years a very important area for collecting Upper Cretaceous fossil vertebrates. So far, the main groups recovered include Testudines, Crocodyliformes and Dinosauria (Theropoda and Titanosauria). The fossil material is usually disarticulated and fragmented and was collected from very fine-grained sandstones, with muddy matrix and cross-stratification and lamination. Testudines are represented by fragments of carapaces and plastrons. Crocodyliformes are composed only of fragmented osteological remains and isolated teeth. Maniraptora is especially represented by isolated teeth, allowing the identification of the Dromaeosaurinae, Velociraptorinae and Troodontidae clades, in addition to some probable endemic groups. Titanosauria is the most representative and abundant group in these fossil localities, however materials are mainly fragments of ribs and some appendicular bones, without diagnostic osteological elements, like caudal vertebrae. The lithological characteristics of the outcrops suggest a paleoenvironment of braided rivers, in an arid climate, with few vegetation cover.