Temporal range: Lower Jurassic
The first specimen discovered by Mary Anning in 1820-21 was missing its skull. She found it on the 'Jurassic Coast' of Lyme Regis, Dorset, England. In 1823 she found another one, this time complete with its skull. The name Plesiosaurus was given by the Rev. William Conybeare.
Plesiosaurus was a fairly typical member of its order, and measured around 3 to 5 metres (10 to 16 ft) in total length. The snout was short, but the jaws were able to open very wide, and had a series of conical teeth in sockets. The neck was quite long, and the short tail was used for steering. Like all plesiosaurs, it used its large paddles to swim.