Opisthocoelicaudia

Opisthocoelicaudia is a genus of titanosaur sauropod dinosaur. It is from Late Cretaceous rocks from Mongolia's Nemegt Basin. In 1965 a well preserved skeleton was found, missing only a neck and head.
Possible synonymy with "Nemegtosaurus".
Scientists are arguing whether "Nemegtosaurus" is a synonym of "Opisthocoelicaudia" or its own genus, or vice versa.