EVIDENCE OF GREGARIOUSNESS IN REBBACHISAURIDS (DINOSAURIA, SAUROPODA, DIPLODOCOIDEA) FROM THE EARLY CRETACEOUS OF NEUQUEN (RAYOSO FORMATION), PATAGONIA, ARGENTINA

For the first time an association of adult and juvenile rebbachisaurid sauropods is described. The material comes from the Early Cretaceous locality of Agrio del Medio (Neuquen, Argentina). The three specimens apparently formed a single group, and their death seems to have been almost simultaneous. The two juvenile specimens are represented by axial and appendicular bones. They show a close relationship with Zapalasaurus bonapartei, which comes from a different sector of the same basin, but which is approximately the same age. The discovery at Agrio del Medio suggests that rebbachisaurid sauropods displayed gregarious behavior. The paleoenvironments in which rebbachisaurids are normally recorded implies a greater tolerance toward extremely arid environments than that shown by macronarian sauropods.