New rebbachisaurid cranial remains (Sauropoda, Diplodocoidea) from the Cretaceous of Patagonia, Argentina, and the first endocranial description for a South American representative of the clade

ABSTRACT

Here we report new rebbachisaurid material (MMCh-PV 71) recovered from the Candeleros Formation (Cenomanian) of northwest Patagonia, Argentina. The cranial remains consist of a partial braincase and a right quadrate. Fractures in the braincase exposed the endocranial cavity, allowing the first study of the brain and inner ear morphologies of a South American rebbachisaurid. The braincase and cranial endocast both exhibit traits similar to those observed in the Cretaceous rebbachisaurs Nigersaurus from Africa and Limaysaurus from Argentina, although in terms of osteology, the South American taxa are highly similar. The endocast of MMCh-PV 71 is more similar to that of Nigersaurus than to those of Diplodocus and Camarasaurus, suggesting some probable rebbachisaurid features such as the noteworthy presence of the flocculus. The overall morphology of the quadrate shows similarities with Limaysaurus and Nigersaurus. However, differences such as the broader posterior fossa and the shape and orientation of the head and the pterygoid process indicate that the new specimen could represent a distinct taxon.

Citation for this article: Paulina Carabajal, A., J. I. Canale, and A. Haluza. 2016. New rebbachisaurid (Sauropoda, Diplodocoidea) cranial remains from the Cretaceous of Patagonia, Argentina, and the first endocranial description for a South American representative of the clade. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1167067.

ACKNOWLEDGMENTS

We thank A. Kamman for access to his land, help during the field work, and support for our activity at the Ernesto Bachmann Museum. We thank Rita and Bernardo, field managers, for making us always feel welcome. We thank the technicians R. Zapata, C. Albornoz, M. Negron, M. Ripoll, G. Gonzalez, M. Soto, A. Moretti, and J. Ochoa for their help during field work and further laboratory preparation. The editor R. Butler and two reviewers, F. Knoll (University of Manchester) and J. L. Carballido (Museo ‘Egidio Feruglio,’ Trelew), provided valuable comments that greatly improved the manuscript. Financial support was provided by the Municipality of Villa El Chocón.