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Name: Liopleurodon (Smooth sided teeth).
Phonetic: Lie-oh-ploor-oh-don.
Named By: Henri-Émile Sauvage - 1873.
Synonyms: Pliosaurus pachydeirus, Pliosaurus pachydirus, Thaumatosaurus mosquensis.
Classification: Chordata, Reptilia, Sauropterygia, Plesiosauria, Pliosauroidea, Pliosauridae.
Species: L. ferox (type), L. pachydeirus.
Type: Carnivore.
Size: Most complete specimen 6.39 meters long, isolated remains suggest that larger individuals reached 7-7.5 meters long.
Known locations: England, France and Germany. Possibly further afield with possible fossils being located in Argentina and Mexico.
Time period: Callovian through to the Tithonian of the Jurassic. Possibly into the early Cretaceous.
Fossil representation: Many specimens, with material from several skulls. Only L.ferox represents an almost complete skeleton.

       Liopleurodon was an apex predator of the Jurassic seas. With a skull, and jaws taking up one fifth of the total length of the animal it had a powerful bite. The twenty centimetre teeth buried deep into the jaws further reinforce this idea. Liopleurodon had a typical pliosaur limb arrangement and although not as efficient as an ichthyic layout, this arrangement of four flippers provides excellent acceleration. The nostrils are very interesting in that the arrangement suggests a directional sense of smell. This would enable Liopleurodon to find its prey while still well out of visual range, perhaps even sensing the blood of fresh kills from other predators like sharks can do today.

       Sizing estimates for Liopleurodon have been changing for the entire time we have known it existed. One thing that is clear is that it was never the twenty-five meter behemoth it was shown to be in the BBC documentary series Walking with Dinosaurs. The most complete specimen (belonging to the species L.ferox) was estimated to six hundred and thirty-nine centimetres long, with a skull one hundred and twenty-six centimetres long. Analysis of all specimens suggest that adult Liopleurodon would range somewhere between five to seven meters long.
       However, a pliosaur skull measuring just over one and a half meters long was attributed to Liopleurodon in 2013 in a study by Benson et al. Going by the principal that the skull of a pliosaur takes up about one fifth of the total body, then this individual Liopleurodon may have measured a little over seven and a half meters long.

Further reading
- Notes sur les reptiles fossiles. - Bulletin de la Société Géologique de France, série 3 1:365-386 - H. -E. Sauvage - 1873.
- The first relatively complete exoccipital-opisthotic from the braincase of the Callovian pliosaur, Liopleurodon. - Geological Magazine 140 (4): 479–486. - Leslie F. Noe, Jeff Liston & Mark Evans - 2003.
- A new species of Kimmeridgian pliosaur (Reptilia; Sauropterygia) and its bearing on the nomenclature of Liopleurodon macromerus. - Proceedings of the Geologists' Association 115: 13–24. - L. F. Noè, D. T. J. Smith, D. I. Walton - 2004.
- A Giant Pliosaurid Skull from the Late Jurassic of England. - PLoS ONE 8 (5): 1–34 - Roger B. J. Benson, Mark Evans, Adam S. Smith, Judyth Sassoon, Scott Moore-Faye, Hilary F. Ketchum, Richard Forrest - 2013.


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