Exploring rebbachisaurid hind-limb anatomy on the basis of a new articulated specimen from the Huincul Formation (upper Cenomanian) of Neuquén Basin, Patagonia, Argentina

Abstract

Rebbachisauridae represents a group of diplodocoid sauropod dinosaurs known from the Early Cretaceous of Europe to the early Late Cretaceous of South America. Despite the rebbachisaurid fossil record being extended in recent years, most of the evidence is represented by incomplete and/or poorly preserved specimens; thus, the morphology of some body-sections, such as the cervical series, the pelvic girdle, and the limb elements, are poorly known or unknown. In this contribution we describe the complete and articulated hind-limbs of a new rebbachisaurid specimen MAU-Pv-EO-629 from the lower section of Huincul Formation (upper Cenomanian) of north-eastern Neuquén Basin (Neuquén Province, Patagonia, Argentina). The morphological features of the appendicular elements, especially of the femur and tibia, not only suggest rebbachisaurid affinities for MAU-Pv-EO-629, but also add new information on the hind-limb anatomy of Rebbachisauridae, which is poorly known to date. Indeed, this represents the first record of a reasonably complete pes in Rebbachisauridae, revealing a phalangeal reduction in rebbachisaurids with respect to other Diplodocoidea, and most sauropods. This new record from the upper Cenomanian of Neuquén Basin provides new information to reconstruct the last stages of the evolutionary history of Rebbachisauridae, before the post-Turonian faunal turnover.