THE POSTCRANIAL OSTEOLOGY OF RAPETOSAURUS KRAUSEI (SAUROPODA: TITANOSAURIA) FROM THE LATE CRETACEOUS OF MADAGASCAR

摘要

Rapetosaurus krausei is a titanosaur sauropod from the Upper Cretaceous Maevarano Formation of northwestern Madagascar and is among the most complete titanosaurs ever discovered. To date, over 15 localities in a 10 km 2 field area have yielded hundreds of titanosaur bones, including associated and articulated specimens of Rapetosaurus. A juvenile skeleton is of particular significance because it was found directly associated with a well-preserved partial skull. The juvenile postcranial skeleton only lacks only the axis, atlas, representative elements from the proximal caudal series, carpals, and tarsals. The Rapetosaurus axial column consists of at least 17 cervical, 10 dorsal, six sacral, and 17 caudal vertebrae. Appendicular skeletal anatomy documents unique aspects of the titanosaur skeleton, and the association of large osteoderms with other, adult specimens confirms the lithostrotian status of Rapetosaurus. These new skeletal data have proven significant for phylogenetic resolution within Titanosauria, particularly because Rapetosaurus can be coded for 83% of over 400 characters for titanosaurs.