Pliosaurus

Pliosaurs were marine reptiles from the Jurassic and Cretaceous Periods. The pliosaurs, along with their relatives, the true plesiosaurs, and other members ofSauropterygia, were not dinosaurs. They originally included only members of the family Pliosauridae, of the Order Plesiosauria, but several other genera and families are now also included, the number and details of which vary according to the classification used.

The group was characterised by having a short neck and an elongated head, in contrast to the long-necked plesiosaurs. They were carnivorous and their long and powerful jaws carried many sharp, conical teeth. Pliosaurs range from 4 to 15 metres and more in length.^[1][2] Their prey may have included fish, ichthyosaurs and other plesiosaurs.

Typical genera include Kronosaurus, Liopleurodon, Pliosaurus and Peloneustes. Fossil specimens have been found in England, Mexico, Africa, South America,Australia, and the Arctic region near Norway.

The name "pliosaur" is derived from Greek, πλειων meaning "more/a higher degree" and σαυρος meaning "lizard". It is adapted from the name of the genus Pliosaurus, which means "more saurian", and was coined in 1841 by Richard Owen, who believed that pliosaurs represented a link between plesiosaurs and crocodilians (considered a type of "saurian"), particularly due to their crocodile-like teeth. Therefore, he named these animals to indicate that they were "more saurian" than the plesiosaurs.

Many very early (from the Rhaetian (Latest Triassic) and Early Jurassic) primitive pliosaurs were very like plesiosaurs in appearance and indeed used to be included in the family Plesiosauridae.