Acostasaurus

Acostasaurus had very large eye sockets and big scleral rings, which helped it see in deep or murky water.1

Its skull was short and wide in the front, unlike many other pliosaurs that had long snouts.1

The only known fossil is a nearly complete skull and parts of the body, including a whole hind flipper and many vertebrae.1

Acostasaurus lived during the Early Cretaceous, a time when few plesiosaur fossils are known, called the 'Lower Cretaceous Gap'.3

It had a short lower jaw joint area with only five and a half pairs of tooth sockets, which is unusual for a pliosaur.1

The specimen was a subadult, because some bones in its skull were not fully grown together.1