Plesiopleurodon was a pliosaur that lived during the Early Cretaceous period. It was anatomically similar to the larger Liopleurodon - a distantly related species that lived millions of years before it.
A Plesiopleurodon was seen in the episode failing to catch an Ornithocheirus.
Behind the scenesEdit
The model of Liopleurodon was reused to represent the creature.
Long neck Plesiosaurs and short neck Pliosaurs are now thought to have flukes on their tails, and not smooth lizard-like tails like in the series.