Pliosaur
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| Pliosaurs Fossil range: 228–65 Ma Late Triassic - Late Cretaceous |
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The Pliosaurs ("more lizards") were marine reptiles from the Jurassic and Cretaceous Periods. They originally included members of the family Pliosauridae, of the Order Plesiosauria, but several other genera and families are now also included; the number and details of which vary according to the classification used. The name is derived from Greek: πλειων meaning 'more/a higher degree' and σαυρος meaning 'lizard'. The pliosaurs, along with their relatives, the true plesiosaurs, and other members of Sauropterygia, were not dinosaurs.
The group was characterised by having a short neck and an elongated head, in contrast to the long-necked plesiosaurs. They were carnivorous and their long and powerful jaws carried many sharp, conical teeth. Pliosaurs range from 4 to 15 meters in length.[1][2] Their prey may have included fish, ichthyosaurs and other plesiosaurs.
Typical genera include Macroplata, Kronosaurus, Liopleurodon, Pliosaurus and Peloneustes. Fossil specimens have been found in England, Mexico, South America, Australia and the Arctic region near Norway.
Many very early (from the Rhaetian (Latest Triassic) and Early Jurassic) primitive pliosaurs were very like plesiosaurs in appearance and indeed used to be included in the family Plesiosauridae.
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[edit] Taxonomy
The taxonomy presented here is mainly based on the plesiosaur cladistic analysis proposed by O'Keefe in 2001[3] and Smith & Dyke in 2008[4]
- Suborder: †Pliosauroidea Welles, 1943 sensu O'Keefe, 2001
- ? Bishanopliosaurus Dong, 1980
- Hauffiosaurus O’Keefe, 2001
- ? Megalneusaurus Knight, 1898
- ? Pachycostasaurus Cruickshank, Martill & Noe, 1996
- ? Sinopliosaurus Young, 1942
- Thalassiodracon Storrs & Taylor, 1996
- Family: Rhomaleosauridae (Nopsca, 1928) Kuhn, 1961 sensu Smith & Dyke, 2008
- Archaeonectrus Novozhilov, 1964
- Eurycleidus Andrews, 1922
- ? Hexatarsostinus
- Macroplata Swinton, 1930
- Maresaurus Gasparini, 1997
- Rhomaleosaurus Seeley, 1874 Paraphyletic
- ? Yuzhoupliosaurus Zhang, 1985
- Family: Leptocleididae White, 1940 sensu Smith & Dyke, 2008
- Leptocleidus Andrews, 1922 Paraphyletic
- Umoonasaurus Kear, Schroeder & Lee, 2006
- Family: Pliosauridae Seeley, 1874 sensu Smith & Dyke, 2008
- Brachauchenius Williston, 1903
- Kronosaurus Longman, 1924
- Liopleurodon Sauvage, 1873
- Peloneustes Lydekker, 1889
- ? Plesiopleurodon Carpenter, 1996
- Pliosaurus Owen, 1841
- ? Polyptychodon Owen, 1841
- Simolestes Andrews, 1909
[edit] Discoveries
In August 2006, paleontologists of the University of Oslo discovered the first remains of a pliosaur on Norwegian soil. The remains were described as "very well preserved as well as being unique in their completeness" and are the first complete skeleton of a pliosaur ever discovered. Whether it belongs to the genus Pliosaurus or Liopleurodon awaits publication of the fossil description. In the summer of 2008, the fossil remains of the huge pliosaur were dug up from the permafrost on Svalbard, a Norwegian island close to the North Pole.[5] The excavation of the find is documented in the 2009 History television special Predator X.
The discovery of another very large pliosaur was announced in 2002, from Mexico. This pliosaur came to be known as the 'Monster of Aramberri'. The size of this specimen has been estimated to be about 15 metres (49 ft) long and it had a 3-metre (9.8 ft) long skull. Consequently, although widely reported as such, it does not belong to the genus Liopleurodon.[6] The remains of this animal consisting of a partial vertebral column, were dated to the Kimmeridgian of the La Caja Formation.[7] The fossils were found much earlier in 1985 by a geology student and were at first erroneously attributed to a theropod dinosaur by Hahnel.[8] The remains also originally contained part of a rostrum with teeth (now lost).
[edit] References
- ^ zoom dinosaurs
- ^ Sea reptile is biggest on record. BBC News, February 27, 2008.
- ^ O'Keefe, F. R. 2001. A cladistic analysis and taxonomic revision of the Plesiosauria (Reptilia: Sauropterygia). Acta Zoologica Fennica 213: 1-63.
- ^ Smith AS, Dyke GJ. 2008. The skull of the giant predatory pliosaur Rhomaleosaurus cramptoni: implications for plesiosaur phylogenetics. Naturwissenschaften e-published 2008.
- ^ Fox News: Predator X Was Most Fearsome Animal to Swim Oceans
- ^ http://www.plesiosaur.com/plesiosaurs/liopleurodon.php
- ^ M.-C. Buchy, E. Frey, W. Stinnesbeck, J.-G. Lopez-Oliva (2003) "First occurrence of a gigantic pliosaurid plesiosaur in the late Jurassic (Kimmeridgian) of Mexico", Bull. Soc. geol. Fr., 174(3), pp. 271-278
- ^ Hahnel W. (1988) "Hallazgo de restos de dinosaurio en Aramberri, N.L., Mexico",Actas Fac. Cienc. Tierra UANL Linares, 3, 245-250.
[edit] See also
[edit] Further reading
- The Plesiosaur Directory - pliosaur page
- Possibly the first full skeleton of a pliosaur was found in October, 2006.
- The monster from the North
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