| Liopleurodon | |
|---|---|
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| L. ferox skeleton, Museum of Paleontology, Tübingen | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | †Sauropterygia |
| Order: | †Plesiosauria |
| Family: | †Pliosauridae |
| Clade: | †Thalassophonea |
| Genus: | †Liopleurodon Sauvage, 1873 |
| Type species | |
| †Liopleurodon ferox Sauvage, 1873
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| Species | |
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| Synonyms | |
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Liopleurodon (/ˌlaɪoʊˈplʊərədɒn/; meaning 'smooth-sided teeth') is an extinct genus of carnivorous pliosaurid pliosaurs that lived from the Callovian stage of the Middle Jurassic to the Kimmeridgian stage of the Late Jurassic period (c. 166 to 155 mya). The type species is L. ferox, which is probably the only valid species. Some studies also include the second species L. pachydeirus, but this latter is considered as a probable junior synonym of L. ferox due to its lack of viable diagnosis. As the holotype specimen of L. ferox consists of a single tooth preserving questionable distinctive features, recent studies therefore recommend the necessary identification of a neotype in order to preserve the validity of the genus. Numerous fossil specimens attributed to Liopleurodon, even including numerous skeletons, have been discovered in Europe, Russia, and Mexico. Other additional species were even proposed, but these are currently seen as coming from other pliosaurid genera.
Liopleurodon is a representative of the Thalassophonea clade, a derived group of pliosaurids characterized by a short neck and a large elongated skull. In 1999, the size of Liopleurodon was greatly exaggerated in the BBC documentary series Walking with Dinosaurs, depicted as reaching 25 m (82 ft) in length. However, the different attributed specimens show that the animal could reach a size ranging from 4 to 8 m (13 to 26 ft) long, with some researchers estimating a maximum length of approximately 10 m (33 ft). Various studies suggest that Liopleurodon would have been an ambush predator, feeding on fish, cephalopods and other marine reptiles.