Augustasaurus hagdorni

Pistosaurs represent the closest relatives to plesiosaurs, and Augustasaurus is seemingly derived to the point of being considered the sister taxon to Plesiosauria. It was a medium sized ocean predator of small fish and other slippery prey, growing up to an adult length of 2-3 meters (6.5-10 feet) with a streamlined body that was already stiffened; much like that of plesiosaurs, to facilitate a pelagic lifestyle. The limbs of Augustasaurus were still similar however, to earlier pistosaurs and nothosaurs; broadened into more paddle-like shapes but not quite to the extant of Plesiosaurs. Augustasaurus' remains have been found in Middle Triassic rocks of the south-western US.