Pliosaurus

Pliosaurus Temporal range: Late Jurassic,
P. macromerus jaw, Natural History Museum
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	†Sauropterygia
Order:	†Plesiosauria
Family:	†Pliosauridae
Clade:	†Thalassophonea
Genus:	†Pliosaurus Owen, 1841
Type species
†Pliosaurus brachydeirus Owen, 1841
Species
P. brachydeirus Owen, 1840 P. brachyspondylus (Owen, 1839) P. carpenteri Benson et al., 2013 P. funkei Knutsen et al., 2012 P. kevani Benson et al., 2013 P. macromerus Philips, 1871 P. portentificus Noè et al., 2004 P. rossicus Novozhilov, 1948 P. westburyensis Benson et al., 2013
Synonyms
Stretosaurus Tarlo, 1960 Spondylosaurus Fischer, 1845 Strongylokroptaphus Novozhilov, 1964 Plesiosaurus giganteus Conybeare, 1824 Plesiosaurus recentior Parkinson, 1822 Liopleurodon rossicus

Pliosaurus (meaning 'more lizard') is a genus of extinct marine reptile. It is included in the family Pliosauridae. Its diet would have included fish, squid and other marine reptiles. This genus has contained several species in the past but it currently consists of the type species P. brachydeirus, the others being P. brachyspondylus, P. portentificus, the very large P. macromerus and P. funkei, and P. rossicus, which lived during the Late Jurassic. Unlike other pliosaurids, Pliosaurus have teeth that are triangular in cross section.

Discovery and species

P. brachydeirus

P. rossicus (right) harassing Leedsichthys problematicus

Currently there are four to six recognized species of Pliosaurus, four of which are known from the Kimmeridge Clay Formation of England. Which ones of the species listed below are recognized as valid depends on the author:

Pliosaurus brachydeirus, Pliosaurus brachyspondylus and Pliosaurus macromerus are all known from the Kimmeridgian of England.

Pliosaurus portentificus is known from the late Kimmeridgian of England. Considered by Knutsen (2012) to be a nomen dubium, with its holotype specimen most likely being a juvenile individual of one of the other species of Pliosaurus

Pliosaurus rossicus is a relatively small pliosaur known from two specimens discovered in Chuvashia, Russia. Knutsen (2012) provisionally retained it as a separate species, but stressed that further examinations are needed to determine whether P. rossicus is indeed a separate taxon or merely a junior synonym of Pliosaurus macromerus. This species was described in 1948 as a species of Pliosaurus; subsequently it was made the type species of the genus Strongylokroptaphus, and later was assigned to the genus Liopleurodon before being assigned to the genus Pliosaurus again by Knutsen (2012).

The sixth species, Pliosaurus funkei, is known from Svalbard. Also known as "Predator X", the species is known from a partial skull, a complete flipper and some assorted remains, including a section of vertebra of two individuals was excavated in mid-2008 in Svalbard, near the Arctic, by a Norwegian team led by Dr. Jørn Hurum. It is claimed by researchers to be the "most fearsome animal ever to swim in the oceans." The remains were discovered in June 2006 during a two-week expedition led by Dr. Hurum of the Natural History Museum at the University of Oslo. The team found 20,000 fragments of the creature's skeleton, which is being preserved and assembled at the museum. Due to the distribution pattern of pliosaurs, scientist believe that species were cosmopolitan, like some groups of modern-day whales.

Using Liopleurodon, another large pliosaurid, as a guide, the Svalbard specimen had been estimated to have been 15 metres (49 ft) long, 45,000 kilograms (99,000 lb) in weight and had teeth 30 centimetres (12 in) long. The jaws of the creature may have been able to exert more force than those of a Tyrannosaurus rex, with one news source stating the bite was over 10 times more powerful than any modern animal and four times more powerful than that of a Tyrannosaurus. It is estimated to have lived approximately 147 million years ago. Analysis of bones from the four flippers suggest that the animal cruised using just two fore-flippers, using the back pair for extra speed when pursuing and capturing prey. P. funkei's brain was of a similar type and size, proportionally, to that of today's great white shark, the team says. Later on, thorough scrutiny of this Svalbard specimen revealed that it was not as massive as originally claimed; total length estimate have been revised to 10.0–12.8 metres (32.8–42.0 ft).

Websites

• http://www.reuters.com/article/scienceNews/idUSL2771508220080227?pageNumber=2&virtualBrandChannel=0
• Gigantic Pliosaurus discovered on Norwegian soil
• Pliosaurus - Naturhistorisk museum
• Sea Monsters: A Prehistoric Adventure Movie - Interactive Time Line - National Geographic
• Britannica Online Encyclopedia