TAPHONOMY AND PALEOPATHOLOGICAL ASPECTS OF NEW VERTEBRATE SPECIMENS FROM THE LATE CRETACEOUS ADAMANTINA FORMATION, NORTHWEST SÃO PAULO, BRAZIL

The Adamantina Formation has yielded a big deal of what we know about the evolution and paleoecology of vertebrates during the Late Cretaceous of Brazil. Many localities in northwestern São Paulo state have produced a diverse and abundant fauna, dominated by crocodylomorphs, dinosaurs and turtles. Paleontological fieldwork in a road recently built in Neves Paulista-SP resulted in the discovery of dinosaur and crocodylomorph remains in a 0.4 m thick reddish sandstone bed with cross laminations. The material includes an isolated crocodyliform vertebral centrum and various titanosaur (Dinosauria, Sauropoda) skeletal parts, i.e. two fused caudal vertebrae, the right portion of a haemal arch proximal process, two portions of the iliac crest, the ventral portion of a sacral rib, and some trunk rib fragments. The assignment to Titanosauria is based on the caudal vertebrae that are procoelic and laterally excavated. Fossils were found disarticulated, except for the fused caudal vertebrae, concentrated in a small area, and without preferential spatial orientation. They exhibit minimal to no abrasion and no hydraulic equivalence to the matrix sediment encasing them, suggesting they were not buried very far from the place of death, although the distance of transportation could be longer if they were also transported as "bloated carcasses". The lack of weathering, trampling, bioerosion, or tooth marks indicate that subaerial exposure of remains before burial was short. The crocodylomorph specimen, found near the titanosaur elements, suggests that they lived associated in the same depositional environment, subject to similar fluvial processes that transported and buried their remains. Additionally, we were able to identify possible pathologies affecting the titanosaur rib and fused caudal vertebrae. The rib presents an irregular lateral surface, similar to a callus, whereas the caudal vertebrae are fused, have ossified tendons near the zygapophyseal articulations, and bone overgrowth affecting the dorsal portion of the most complete element. The causes of these pathologies are still under study, but our results expand the record of abnormalities in sauropod skeletal remains and also contributes to the understanding of taphonomic processes involved in the vertebrate preservation in the Adamantina Formation.