The Pliosaurs were aquatic mesozoic reptiles, from the Jurassic and Cretaceous periods. They originally included were members of the family Pliosauridae, in the order Plesiosaura, but several other genera and families are now also included, the number and details of which vary according to the classification used. The name is derived from Greek: πλειω - from the verb to sail or πλειων - a fin and σαυρυς - a lizard.

This group was characterised by having a short neck and an elongated head, in contrast to the long-necked plesiosaurs. They were more crocodile-shaped. However, the four-paddle swimming action, using the large flipper-like fins was shared and they were possibly better adapted to deeper waters. They were carnivorous and their long and powerful jaws carried many sharp teeth. Their prey may have been ichthyosaurs and other plesiosaurs.

Typical genera include Macroplata, Kronosaurus, Liopleurodon, Pliosaurus and Peloneustes. Fossil specimens have been found in England and South America.

Many very early (from the Rhaetian (Latest Triassic) and Early Jurassic) primitive pliosaurs were very like plesuiosaurs in apperance, and in the past were included in the family Plesiosauridae

These aquatic reptiles were not dinosaurs.

See also

• Plesiosaur
• Plesiosauria

Sauropterygia

Pliosaure