Crocodyliforms of the São José do Rio Preto Formation (Bauru Basin, Upper Cretaceous), taxonomic and preservational aspects

Abstract

The São José do Rio Preto Formation (Upper Cretaceous, Bauru Basin) contains a rich vertebrate fossil assemblage, primarily composed of isolated remains of fish, chelonians, crocodyliforms, and dinosaurs. We report the newly discovered specimens of crocodyliforms (cranial and mandibular bones, osteoderms, and teeth) and review the previously described specimens of this clade. Our investigations point to the presence of four distinct clades in this formation: Baurusuchidae, Peirosauridae, Sphagesauria, and Itasuchidae. Xenodontosuchians (i.e., Baurusuchidae + Sphagesauridae) are rare; most of the fossils are identified as Itasuchidae, with at least at two taxa present in the formation, Epoidesuchus and the new species Ibirasuchus gelcae gen. et. sp. nov. Among the reviewed specimens, we reidentified a set of six isolated teeth previously attributed to the family Candidodontidae as belonging to the order Sphagesauria. The fluvial-lacustrine nature of the depositional environment of the São José do Rio Preto Formation likely contributed to the diversity and abundance of itasuchids, a taxon considered to be semi-aquatic. The occupation of distinct environments and ecological niches by Xenodontosuchia and itasuchids may indicate that their paleoecology has directly influenced their preservation processes and, consequently, that this aspect should be taken into consideration when analyzing the crocodyliform diversity in the Bauru Basin.