Plesiosaurus was the first species of plesiosaur to be discovered and described by scientists, in 1821.
It was a cousin to Cryptoclidus from WWD and Elasmosaurus from Sea Monsters, but at 3.5 m in length it was smaller than both of them, though similar in appearance - 'a snake threaded through the body of a turtle'. Like the Ichthyosaurs, it had an increased number of joints in its' digits. However, it still had flippers, rather than flukes. Its neck was long and serpentine, allowing Plesiosaurus to reach far beyond what could be expected from a modest-sized animal (by Mesozoic standards), but contrary to the initial beliefs, it wasn't very flexible.
Because it was discovered so long ago, nowadays it is considered a wastebasket taxon. Just like the other plesiosaurs Plesiosaurus probably fed on fish and other small animals, such as squid, ammonites and belemnites that it could fit into its mouth and swallow whole. It may or may not have come ashore at night to escape from such predators as Liopleurodon.
In The Walking With... Series
Plesiosaurus is one of the viewable plesiosaurs in the app.
In Related Media
The Underground World
Plesiosaurus was featured in the 1678 book The Underground World as a dragon that supposedly lived during ancient times in Holzmaden.