Biology

All plesiosaurs have four flippers, a short body and a short tail. The skeleton below belongs to Meyerasaurus victor, one of the most complete plesiosaur specimens ever found. It shows the ventral surface (underside) of the animal (redrawn from Fraas 1910).

What did plesiosaurs eat and how do we know?

Types of evidence for diet

Pollard (1990) established three broad categories of evidence for diet in prehistoric organisms: direct evidence, indirect evidence and general evidence. Direct evidence consists of various grades of gut contents, indirect evidence includes bite marks, and general evidence consists of functional analyses.

Introduction

Plesiosaurs belong to a larger group of reptiles known collectively as the Sauropterygia. Sauropterygians had a worldwide distribution (Rieppel 1997) and range in age from the Triassic Period to the end of the Cretaceous Period (Benton 1990a).

How did plesiosaurs swim?

There is no other animal with four large flippers like a plesiosaur. This has led to much debate about plesiosaur locomotion (Robinson 1975). The tail in plesiosaurs is short, so while it may have provided some assistance as a rudder, it was not used for propulsion.

Contrary to early work (Zarnik 1925), plesiosaur necks did not have the extreme flexibility required to coil up and strike prey in the manner of some snakes and pleurodiran turtles (Pough et al. 1996). Tall neural spines on the top of the neck vertebrae limited vertical (up and down) flexibility, while processes on the anterior and posterior surfaces of the vertebrae (prezygapophyses and postzygapophyses) limited horizontal (side to side) mobility.