Liopleurodon: Top Jurassic Marine Predator

Liopleurodon was a giant predatory marine reptile that lived in the Late Jurassic Period. It belonged to a group of plesiosaurs known as pliosaurs, which had much shorter necks than their better-known relatives like elasmosaurus or plesiosaurus. Fossils have been well preserved from several locations in Europe, so we have a good idea of what the animal looked like overall.

This giant marine beast had four long and powerful flippers which propelled it forcefully through the water, a crocodile-like body, and a giant diamond-shaped skull. Its size has been an issue of debate, since there are many fragmented bones belonging to pliosaurs that suggest these beasts could be upward to 20 meters long. However, this is all speculative and complete remains of liopleurodon put it in the range of 7 to 10 meters in length. Even at this size it would have been a formidable predator in the Jurassic oceans, dominating the food chains over other predators like sharks. A 2002 discovery of the remains of a possibly juvenile pliosaur 18 meters long suggests that pliosaurs on the whole could reach much longer lengths. Again, this evidence is speculative and might not even apply to liopleurodon itself. Currently, the fossil record of liopleurodon does not live up to its near mythical status as the largest carnivore ever to live on the Earth in popular programs like the BBC's "Walking with Dinosaurs."

Studies of liopleurodon skulls have suggested that the marine reptile could actually sense direction of smells by drawing water in through its nostrils. This could help it to determine the location of prey more easily in dark water. The skull itself was up to ten feet long, with rows of wicked teeth nearly a foot long. It seems likely that liopleurodon swallowed most of its prey whole or in large chunks. It was likely an opportunistic hunter, attacking anything that it could catch in order to maintain its giant body weight. Although reptiles and other ectothermic animals need smaller amounts of food than endothermic mammals to fuel their metabolism, the giant pliosaurs did not have the luxury of basking in the sun like terrestrial reptiles. In order to keep moving, liopleurodon would have required many hundreds of pounds of food per week.

Liopleurodon did not live past the Jurassic, and the role of top predator in the seas passed on to giant mososaurs like tylosaurus during the Cretaceous Period. In turn, those mososaurs would go extinct along with the dinosaurs, ushering in a new dynasty of top whale and shark predators during the Cenozoic Era.