The Online Library of Knowledge

Marine reptiles

Plesiosaurus

PlesiosaurusPlesiosaurus Plesiosaurus was a marine reptile that lived in the Early Jurassic Period. It gives its name to a wide range of related animals called the plesiosaurs. It had a short head, a long neck, a sturdy, bulky, finless body and a relatively short, tapering tail. Its skin was smooth, rather than scaly. It had long narrow flippers, each containing five internal fingers, made up of a number of smaller bones. There were many conical teeth, set in sockets. Plesiosaurus's large nostrils were on top of its head. They gave it a keen sense of smell, allowing it to detect prey from far off.

Fishing technique

The head of PlesiosaurusThe head of PlesiosaurusPlesiosaurus used its long neck to good effect, craning forward to snap up small marine creatures in its jaws. Its lower jaw and sharp, interlocking teeth worked well as a fish trap. Although its snout was short, its jaws opened extremely wide. 
 
 
 

Animation of Plesiosaurus swimmingAnimation of Plesiosaurus swimmingClick to play video

Propulsion

Palaeontologists once thought that plesiosaurs used their flippers like large oars in a back-and-forth motion to propel themselves through the water. Now it is thought that they worked them in the same way that a bird flaps its wings: with strong, steady, up-and-down strokes. The flippers’ structure is closer to that of modern penguins and sea turtles, which “fly” in this way. 
 

Plesiosaurus means “near lizard”. It was given this name in 1821, to show that it was more closely related to land reptiles than Ichthyosaurus, whose fossil had also been found in nearby rocks.

© 2019 Q-files Ltd. All rights reserved. Switch to Mobile