The southernmost records of Rebbachisauridae (Sauropoda: Diplodocoidea), from early Late Cretaceous deposits in central Patagonia

Abstract

We describe new and redescribe previously discovered sauropod dinosaur material from the Upper Cretaceous (middle Cenomanian–Turonian) Bajo Barreal Formation of south-central Chubut Province, central Patagonia, Argentina. The remains consist of associated and isolated axial skeletal elements recovered from three separate localities, and are herein assigned to the morphologically aberrant Rebbachisauridae clade. Several of the fossils exhibit osteological characters that were previously undocumented in rebbachisaurids, enhancing our understanding of the morphological diversity of this enigmatic sauropod group. In particular, the Bajo Barreal material demonstrates the occurrence within Rebbachisauridae of bifurcate neural spines in cervical vertebrae and well-developed, presumably pneumatic fossae in caudal vertebrae; among Diplodocoidea, these distinctive morphologies had previously been recognized only in flagellicaudatans. Furthermore, the Bajo Barreal fossils constitute the southernmost known occurrences of Diplodocoidea, adding to the globally sparse Late Cretaceous record of these sauropods and augmenting our knowledge of central Patagonian terrestrial vertebrate assemblages during this interval.