PRELIMINARY DESCRIPTION OF A NEW SAUROPOD DINOSAUR FROM THE HUINCUL FORMATION (CENOMANIAN), AT NEUQUÉN PROVINCE, PATAGONIA, ARGENTINA

BELLARDINI, FLAVIO; FILIPPI, LEONARDO

Corrientes

Jornada; XXXII jornadas argentinas de paleontología de vertebrados; 2018

Universidad Nacional Nordeste, APA

At the end of 2017, a new partially articulated skeleton of a sauropod dinosaur was found in deposits of the Upper Cretaceous in the northwest of the Neuquén basin. The materials come from a thick sequence of sandstones corresponding to the Huincul Formation in the ?El Orejano? locality, 70 km south from Rincón de los Sauces (Neuquén Province). Hitherto, we recovered an almost complete left hind-limb (MAU-Pv-EO-629). In proximal view, the proximal epiphysis of the tibia is antero-posteriorly expanded and transversally compressed, as well as in Zapalasaurus Salgado, Carvalho and Garrido, 2006 and the rebbachisaurid from ?La Antena? (MMCH-PV-45), thus in contrast with most diplodocids and Titanosauriformes which present a more rounded proximal shape. In lateral view, the cnemial crest is rounded in shape, and directed anteriorly as in MMCH-PV-45, Zapalasaurus and other rebbachisaurids. The diaphysis is straight, as in other neosauropods, differing from derived titanosaurs where is more sinusoidal. The fibula is also straight, slightly longer than the tibia. The proximal epiphysis is oval in shape, while the distal one is ?D-shaped?, as in most neosauropods. The astragalus is not clearly observable, being in articulation with the zeugopodium, while the calcaneus is not present. In the pes, the metatarsal III is the longest element of the sequence, while the digits III and IV show two altered phalanges. Pending the rescue of the remaining elements, we report here a new Neosauropoda specimen, probably belonging to Rebbachisauridae, from the Huincul Formation, whose sauropod record is represented by both rebbachisaurid and macronarian forms.