Liopleurodon, a Thalassophonean Pliosaur that lived from the Callovian-Kimmeridgian stages of the Jurassic Period. Roughly the size of an Antarctic type A Killer Whale, it could reach a length of about 7-8 meters(22-26 feet). It was one of the Apex Predators of the Northern European Waters.
Liopleurodon Skull
Liopleurodon (/ˌlaɪoʊˈplʊərədɒn/; meaning 'smooth-sided teeth') is an extinct genus of large, carnivorous marine reptile belonging to the Thalassophonea, a clade of short-necked pliosaurid plesiosaurs. Liopleurodon lived from the Callovian Stage of the Middle Jurassic to the Kimmeridgian stage of the Late Jurassic Period(c. 166 to 155 mya). It was the apex predator of the Middle to Late Jurassic seas that covered Northern Europe. The largest species, L. ferox, is estimated to have grown between 7-8 metres (22-26 ft) in length based on a large skull.
Discovery & Species[]
The genus name Liopleurodon was coined by Henri Émile Sauvage in 1873. Sauvage named three species which he assigned to this genus, each based on a single tooth. One tooth, its crown measuring 7.5 centimetres (3.0 in) long, was found near Boulogne-sur-Mer, France(The only region in France where its fossils have been found), in layers dating from the Callovian, and was named Liopleurodon ferox. However, in 1880, Sauvage synonymized Liopleurodon with Polyptychodon, noting that it was similar to this genus, but distinct from Plesiosaurus and Pliosaurus. In 1888, Richard Lydekker, after studying some teeth attributable to Liopleurodon ferox in the Leeds Collection, concluded that they were so similar to those of Pliosaurus that they should be placed in that genus. These teeth had been collected by Alfred Leeds from the Oxford Clay Formation, near Peterborough, England. In 1994, in Boulogne-sur-mer and Lorraine, Northern France, Paleontologist Pascal Godefroit discovered the remains of a Pliosaur which was assigned the name Simolestes Keileni, however, the generic identification was doubted by the PhD thesis of Noè (2001), but it was not until at least 2021 that the holotype began to be rigorously reexamined by Sven Sachs of the Bielefeld Natural History Museum. Sachs published his results in a 2023 multi-authored study, which found that MNHNL BU159 belonged to a more derived lineage than Simolestes. This thus warranted a new genus, which they named Lorrainosaurus, a portmanteau of the type locality Lorraine and Ancient Greek σαῦρος (sauros, "reptile").
Liopleurodon’s fossil origin occurred in Northern Europe, mainly in England, Northern France, and Germany. Fossil specimens that are contemporary (Callovian-Kimmeridgian) with those from England and France referrable to Liopleurodon are known from Germany. In 2013, Roger Benson and colleagues considered both the outdated specimens of Liopleurodon, "L." macromerus(Which was from Wiltshire, England) and "L." rossicus(Which was from Western Russia) nowadays belonged to the species Pliosaurus. They also considered Liopleurodon to be restricted to the Middle-Late Jurassic. In 2015, Jair Israel Barrientos-Lara and colleagues described two pliosaurid fossils found near the town of Tlaxiaco in Oaxaca, Mexico. These fossils were extracted from Kimmeridgian deposits in the Sabinal Formation, and one of them, the partial front end of a snout, was attributable to Liopleurodon, though the researchers considered the remains too fragmentary to provide a species-level identification. Liopleurodon grossouvrei, although synonymized with Pliosaurus andrewsi by most authors, was considered to potentially be a distinct genus in its own right by Davide Foffa and colleagues in 2018, given its differences from P. andrewsi and Liopleurodon ferox. Madzia and colleagues in 2022 noted that the fact that Liopleurodon was named based on a single tooth of dubious distinctiveness is problematic, and that a more complete neotype may need to be designated to preserve the stability of L. ferox. They also stated that further study of the taxon was needed to confirm that the supposed differences between L. ferox and L. pachydeirus were indeed due to individual variation.
Description[]
Liopleurodon ferox first came to the public attention in 1999 when it was featured in an episode of the BBC television series Walking with Dinosaurs, which depicted it as an enormous 25 m (82 ft) long and 150 t (330,000 lbs) predator; this was based on very fragmentary remains, and considered to be an exaggeration for Liopleurodon, with the calculations of 20-metre (66 ft) specimens generally considered dubious. Estimating the size of pliosaurs is difficult because not much is known of their postcranial anatomy. The palaeontologist L. B. Tarlo suggested that the pliosaurs’ total body length can be estimated from the length of their skull which he claimed was typically one-seventh of the former measurement. Additional Kronosaurus specimens and a skeleton of L. ferox, GPIT 1754/2, show that the pliosaurs’ skulls were actually about one-fifth of their total body length. One large skull specimen of L. ferox, CAMSMJ.27424, has an estimated total body length of 6.39m (21.0 ft). McHenry estimated that smaller individuals measuring about 4.8–5.7 m (16–19 ft) long would have weighed around 1–1.7 t (2,200–3,700 lbs) based on the specimen NHM R2680.
Some researchers propose that the larger specimens had a length of 10 m (33 ft). Tarlo applied the aforementioned one-seventh ratio of skull length to body length, estimating that the largest known specimen of L. ferox was a little over 10 m (33 ft), though a more accurate, typical size range would be between 5 to 7 meters (16 to 23 ft).
Paleobiology[]
Four strong paddle-like limbs suggest that Liopleurodon was a powerful swimmer. Its four-flipper mode of propulsion is characteristic of all plesiosaurs. A study involving a swimming robot has demonstrated that although this form of propulsion is not especially efficient, it provides very good acceleration—a desirable trait in an ambush predator. Studies of the skull have shown that it could probably scan the water with its nostrils to ascertain the source of certain smells.
A fragmentary specimen possibly belonging to a young adult individual, PETCM R.296, contained numerous hooklets of teuthoid cephalopods, fish bones and a single reptilian tooth in its stomach. Although its exact dietary preference cannot be determined, Martill proposed three suggestions. One possibility is that Liopleurodon could have fed on food supplies that are abundant (i.e. squids), but considering that plesiosaurs and ichthyosaurs were also abundant and that the plesiosaurs' swimming speed is likely very slow compared to squids, this interpretation may be unlikely unless Liopleurodon was an ambush predator. Another possibility is that Liopleurodon may have been an opportunistic feeder, with cephalopod hooklets being representative of the acid resistant residue of its varied diet—skeletal components of various vertebrates that lost to the acid environment of the gut; however, since the thin sections through the gut don't reveal the presence of otoliths (calcium carbonate structure of vertebrates located in the vestibular labyrinth) which are known to occur in the gut of cetaceans, fish may not have been an important part of its diet. The other possibility is that the pliosaur fed on large cephalopod-feeders, with the hooklets representing the residues of the stomach contents of the pliosaur's prey, but there is no firm evidence to this claim. It is also notable that this specimen preserved at least 7 gastroliths, which probably weren't used for grinding based on the well-preserved conditions of the hooklets. It is possible either that the pliosaur accidentally swallowed the stones and they remained in its gut, or that the stones represent the "acid resistant residue from carbonate cemented sandstone."