Information about Liopleurodon

Liopleurodon Fossil range: Middle Jurassic
Liopleurodon ferox Liopleurodon ferox
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Sauropsida Order: Plesiosauria Suborder: Pliosauroidea Family: Pliosauridae Genus: Liopleurodon Sauvage, 1873
Species
L. ferox Sauvage, 1873 (type) L. pachydeirus (Seeley, 1869) L. rossicus (Novozhilov, 1948) L. macromerus (Phillips, 1871)

Liopleurodon (IPA: /lioʊ.ˈplʊ.ɹʌ.dɑn/, meaning 'smooth-sided teeth') is a genus of large, carnivorous marine reptiles belonging to the Pliosauroidea, the short-necked plesiosaur group. Liopleurodon lived during the Callovian stage of the Middle Jurassic Period (c. 160 million to 155 million years ago (mya)).

Anatomy, morphology and physiology

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 character in an ambush predator.^[1][2] Studies of the skull have showed that it could probably scan the water with its nostrils to ascertain the source of certain smells.^[3] Liopleurodon was carnivorous and it is unlikely that it had many, if any, predators.

Size issue

The issue of its maximum size has been somewhat controversial. Most fossil evidence of Liopleurodon ferox seems to indicate that these beasts grew from 7 to 10 meters (23-33 feet) long. However, as with its relative Kronosaurus, there is some uncertainty whether current reconstructions are correct. Fossil evidence from Great Britain indicates much larger contemporary pliosaurs, up to 18 meters (60 feet long) or even longer but the evidence is too fragmentary to determine whether the find belonged to Liopleurodon or to a species from some other genus. A mandible on display in the Oxford University Museum of Natural History estimated over 3 meters (preserved 2.875m) has been thought to belong to L.macromerus (originally Stretosaurus).^[4] There have been unconfirmed reports of a 4 meter (14 feet long) long lower jaw of an unknown species of giant pliosaur found on the Dorset coast.



In 2002, the discovery of a very large pliosaur in Mexico was announced. This came to be known as the 'Monster of Aramberri'. Even conservative estimates gave a length of at least 15 meters, despite the possibility of it being a juvenile specimen. However, although widely reported as such, it did not belong to the Liopleurodon genus. The remains of this animal consisting of a partial vertebral column, and dating from the Kimmeridgian La Caja Formation of Mexico, have been described by M.-C. Buchy et al. in 2003.^[5] The fossils were actually found much earlier in 1985 by a geology student and were at first erroneously attributed to a theropod dinosaur by Hahnel.^[6] The remains also originally contained part of a rostrum with teeth (now lost).

Estimates of maximum size had already been circulated in the 1999 BBC documentary series Walking with Dinosaurs, where an enormous pliosaur was presented as a 25-meter-long Liopleurodon. If this size given by the BBC is regarded as accurate then it would make Liopleurodon the largest marine predator of all time and so the largest predator of all time.

Range and distribution

Fossils of the creature have been found mainly in Germany, France, Russia and the United Kingdom, from the Jurassic period, when Europe was covered by a large sea.

Evolutionary history

Discovery

The genus name Liopleurodon was coined by H.E Sauvage in 1873 ^[7] on the basis of very poor remains consisting of three big 70 mm teeth (one tooth found near Boulogne-sur-Mer, France, in layers dating from the Callovian stage of the Jurassic was named Liopleurodon ferox, another from Charly, France was named Liopleurodon grossouvrei, and a third discovered near Caen, France and originally described as Poikilopleuron bucklandi was ascribed by Sauvage to the species Liopleurodon bucklandi). Sauvage did not ascribe the genus to any particular group of reptiles in his descriptions.

Nowadays, there are three of four recognized species of Liopleurodon: L. ferox from the Callovian of England and France, L. pachydeirus from the Callovian of England, described by Seeley as a Pliosaurus (1869), ^[8] L. rossicus from from the Volgian of Russia described by Novozhilov (1948) also as a Pliosaurus,^[9] and L. macromerus, from England, described by Phillips as a Plesiosaurus (1871). ^[10] Only L. ferox is known from more or less complete skeletons.

In popular culture

In 1999, Liopleurodon was featured in an episode the BBC television series Walking with Dinosaurs. In the program, a Liopleurodon was depicted attacking and devouring a land-dwelling dinosaur (Eustreptospondylus), before becoming beached during a typhoon and suffocating under its own weight. The depiction of Liopleurodon leaping onto the land in order to catch land-based prey is entirely speculative, though the program's producers state that the behavior was inspired by that of orcas.^[11] Liopleurodon subsequently appeared in a 2003 follow-up to Walking With Dinosaurs entitled Sea Monsters. Having been featured in the popular BBC series, Liopleurodon later appeared in such films as , and as a humorous non-sequitur in the Internet-based Jason Steele short Charlie the Unicorn.^[12]

Bibliography

References

External links

• Liopleurodon genus info at The Plesiosaur Directory
• Liopleurodon fact file from BBC, with pictures and video