Liopleurodon

Liopleurodon was a pliosaurid reptile from the late Jurassic period. It is probably the most famous marine reptile due to its ferocity and its appearance in Walking with Dinosaurs. It was one of the top predators in the water when it was alive. It died out due to climate change and the ceaseless shifting of the continents.

Description
Liopleurodon was a medium-sized pliosaur. It had the common pliosaur build: short neck, streamline body, large paddles. It has sharp, peg-like teeth protruding from its jaws, used for tearing off bits of flesh.

Diet
Liopleurodon, like all pliosaurs, were predators. They hunted large fish, marine reptiles like the aquatic crocodylian Metriorhynchus, sharks like Hybodus and young, sick and injured Leedsichthys. Like all carnivores, Liopleurodon was also a scavenger.

Size
Liopleurodon was 6 metres long. However, there has been hot debate over its size. In the Walking with series, it was depicted as 25 metres long and 150 tonnes in weight and was able to pluck dinosaurs like Eustreptospondylus off dry land. That is not true.

Pilot
A Liopleurodon was seen beached on a beach.

Cruel Sea
An old bull Liopleurodon was seen plucking an fishing Eustreptospondylus off some rocks and drowning it. It was later seen killing a mother Opthalmosaurus in labour, killing the unborn pup in the process. The old bull and a female later fought over territory. The bull tore off one of the female's hind paddles and won the fight. After a storm, the bull was left stranded on a beach and died. His remains were eaten by a group of Eustreptospondylus.

The Second Most Deadliest Sea
An adult Liopleurodon was seen feeding off of a dead Leedsichthys before swimming off. Later, Nigel Marven later tested two different chemicals to see which was better at repelling attacking Liopleurodon. During the tests, two juvenile Liopleurodon attacked a dummy filled with squid. The first chemical did nothing whilst the second (putrizene) repelled the Liopleurodon.

During the night, Nigel found a pod of Liopleurodon feeding on the Leedsichthys carcass. One came too close and Nigel ejected putrizene from his diving suit and repelled it. The pod then swam off full.

Primeval

 * Read more at Primeval Wiki!

The Lost Island
A Liopleurodon came through one of the Anomalies on Guns Island into the Atlantic Ocean in the Present, where it attacked and sank a trawler boat. The ARC team later encountered the Liopleurodon in the oceans, and it was resistant to bullets they fired at it but was dying from the Atlantic Ocean's cold conditions. Presumably, the Liopleurodon eventually died due to the colder conditions of the water in the present day Atlantic Ocean.

Episode 5.2
A Liopleurodon came through an Anomaly into the North Sea in the Present, where it attacked a Nuclear Submarine several times; slamming into it, biting down on its tracking device and jamming its propeller. When the submarine was pulled through the Anomaly, the Liopleurodon followed it through back into its home in the Jurassic oceans.

In the Jurassic, three Liopleurodon attacked the submarine, repeatedly slamming into and scraping against it. One of them investigated a Bathyscaphe from the submarine until Matt Anderson and Abby Maitland turned the bathyscaphe's lights off to make it seem dead. Eventually, when the team ejected a Swimming Theropod from the submarine, one of the Liopleurodon devoured it, distracting the creatures long enough for the submarine to return through the Anomaly.

Trivia

 * The model of Liopleurodon was reused for the Plesiopleurodon in Giant of the Skies.

Errors

 * The Liopleurodon in the Walking with series is shown to be 25 metres long and 150 tonnes.  In reality it was 6 metres long and 2 tonnes.