Opisthocoelicaudia.
Opisthocoelicaudia is a genus of sauropod dinosaur of the Late Cretaceous discovered in the Nemegt Formation in the Gobi Desert of Mongolia. Named and described by Polish paleontologist Maria Magdalena Borsuk-Białynicka in 1977, the type species is Opisthocoelicaudia skarzynskii. A well-preserved skeleton lacking only the head and neck was unearthed in 1965 by Polish and Mongolian scientists, making Opisthocoelicaudia one of the best known sauropods from the Late Cretaceous. Tooth marks on this skeleton indicate that large carnivorous dinosaurs had fed on the carcass. Two more specimens have been found, including part of a shoulder and a fragmentary tail. A relatively small sauropod, Opisthocoelicaudia measured about 11.4–13 metres (37–43 ft) in length. Like other sauropods, it would have been characterised by a small head sitting on a very long neck and a barrel-shaped trunk carried by four column-like legs. It may have been able to rear on its hind legs.
