The first record of sauropod dinosaurs from Antarctica

IGNACIO A. CERDA; ARIANA PAULINA CARABAJAL; LEONARDO SALGADO; RODOLFO A. CORIA; JUAN J. MOLY

Congreso; 71th meeting of the Society of Vertebrate Paleontology; 2011

Sauropods were one of the most widely distributed group of dinosaurs for most of theMesozoic Era, although this clade has not been previously recorded in Antarctica. Here we report the first record of a sauropod dinosaur from Antarctica, represented by an incomplete caudal vertebra from the Late Cretaceous of the James Ross Island (Antarctic Peninsula). The vertebra was collected from marine sediments assigned to the Gamma Member of the Santa Marta Formation (Campanian), constituted mainly by fine-grained to mid-size grainedsandstones. The specimen consists of a strongly procoelous middle caudal centrum lacking the neural arch. The centrum length (excluding the posterior ball) is 170 mm and its height is 105 mm. There is no pleurocoels, and a sagittal fracture has exposed the internal bone structure, which is not pneumatized. The morphology and size of the specimen allow it to be identified as a caudal vertebra of a derived sauropod dinosaur. The anterior position of the neural arch indicates referral to Titanosauriformes. The procoely of the middle caudal vertebra has been proposed to have a diagnostic feature of lithostrotian titanosaurs. The biogeographical history of sauropods and the interrelationships amongst titanosaurs from southern landmasses remain obscure and controversial. The specimen is notable for representing the first Antarctic sauropod record, but also the most southern record of the clade, adding new data in the process of resolving the affinities of South American titanosaurs and the understandingof Gondwanan paleobiogeography.