Sauropterygia

Sauropterygia Temporal range: Lower Triassic – Upper Cretaceous
The pliosaur Kronosaurus hunts a plesiosaur: by Dmitry Bogdanov.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Superorder:	†Sauropterygia Richard Owen, 1860

The Sauropterygia was a superorder of successful aquatic reptiles that flourished during the Mesozoic era. They are united by an adaptation of their shoulder, designed to support powerful paddle strokes. Some later sauropterygians like the pliosaurs developed a similar mechanism in their pelvis.

Origins and evolution

The earliest sauropterygians appeared about 245 million years ago, at the start of the Triassic period. At first they were small, less than a metre. They were semi-aquatic lizard-like animals with long limbs (called pachypleurosaurs). They developed into a group called the nothosaurs, several meters long. The sauropterygians included another very distinctive group: the placodonts. They were bottom-feeders on shellfish, and possessed flat, crushing teeth to handle their prey.^p148–151

The end-Triassic extinction event wiped them all out except for the plesiosaurs. During the earliest Jurassic these diversified quickly into the long-necked small-headed plesiosaurs proper, and short-necked large-headed pliosaurs.

Orders

• Nothosaurs
  • Pachypleurosaurs
• Placodonts
• Plesiosaurs

Position uncertain

• Pistosaurus

Other websites

• A review of the Sauropterygia Archived 2007-07-06 at the Wayback Machine. Adam Stuart Smith. The Plesiosaur Directory. Retrieved April 17, 2006.
• Paleofile taxalist - lists every species and synonyms. Retrieved February 26, 2006