Pistosaurus

Pistosaurus longaevus is an extinct genus of aquatic sauropterygian reptile closely related to plesiosaurs. Fossils have been found in France and Germany, and date to the Middle Triassic.

Description
Pistosaurus was about 3 metres (10 ft) long, and had a body form resembling that of nothosaurs, aquatic reptiles that flourished during the Triassic. However, the vertebral column was stiff, like that of a plesiosaur, implying that the animal used its paddle-like flippers to propel itself through the water, as the plesiosaurs probably did. The head also resembled that of a plesiosaur, but with the primitive palate of a nothosaur, and numerous, sharp teeth ideal for catching and eating fish.

Classification
Although it is unlikely that Pistosaurus was a direct ancestor of the plesiosaurs, the mixture of features suggests that it was closely related to that group.[1]

The following cladogram follows an analysis by Ketchum & Benson, 2011.