Morphological diversity of Neuquensaurus Powell, 1992 (Sauropoda; Titanosauria): insights from geometric morphometrics applied to the vertebral centrum shape.

Neuquensaurusis a small-sized titanosaur from the Upper Cretaceous of Patagonia, Argentina, for which two species were recognised in the past (Neuquensaurus australisandNeuquensaurus robustus). Given that such division was only based on the relative robustness of the limb bones, the validity of the speciesN. robustushas been questioned. In this work, we studied the morphological variation of the vertebrae of this genus through geometric morphometric techniques and the description of relevant anatomical features in order to assess if there are one or more morphotypes withinNeuquensaurus. We found two distinguishable morphotypes, one belonging toN. australisand other that includes specimens assigned to bothN. australisandN. robustus. The occurrence of a posterior cervical vertebra with a particular anatomical feature (i.e. four sprl) could indicate the presence of another taxon thanN. australisin the studied sample. Although the validity of the speciesN. robustuscannot be discussed on the basis of the current data, our study supports the hypothesis of at least two different morphotypes ofNeuquensaurus(which could be related to different taxa). [ABSTRACT FROM PUBLISHER]