Cetiosaurus

Cetiosaurus Temporal range: Middle Jurassic-Late Jurassic, 181–169 Ma PreЄ Є O S D C P T J K Pg N
Fossils of C. oxoniensis at the Oxford University Museum of Natural History
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Sauropodomorpha
Infraorder:	Sauropoda
Family:	Cetiosauridae
Subfamily:	Cetiosaurinae Lydekker, 1888
Genus:	Cetiosaurus Owen, 1842
Species
C. medius Owen, 1842 (type, may be suppressed by ICZN) C. brevis Owen, 1842 C. longus Owen, 1842 C. mogrebiensis Lapparent, 1955 C. oxoniensis Phillips, 1871 (proposed as new type species)

Cetiosaurus (SEET-ee-oh-sawr-us) meaning 'whale lizard', from the Greek cetus/κητος meaning 'sea monster' (later, 'whale') and saurus/σαυρος meaning 'lizard', was a sauropod dinosaur from the Mid to Late Jurassic Period (181-169 million years ago) in what are now Europe and Africa. It is estimated to have been about 53 feet (16 m) long and to have weighed roughly 24.8 tonnes (27.3 short tons). It was so named because its discoverer, Sir Richard Owen supposed it was a marine creature, initially an extremely large crocodile.

It was a primitive, quadrupedal, long-necked, small-headed herbivore, with a shorter tail than most sauropods.

Description

Restoration

Cetiosaurus was a long-necked quadrupedal animal approximately 18 meters (59 ft) long. Its neck was as long as its body, and the tail was considerably longer, consisting of at least 40 caudal vertebrae. Its dorsal vertebrae, the bones along the back, were heavy and primitive, unlike the hollowed-out bones of advanced sauropods like Brachiosaurus. Its forearm, too, was as long as the upper arm, unlike most other sauropods. Its thigh bone was approximately six feet in length.

Discovery and species

Cetiosaurus was the first sauropod to be discovered and named as well as being the best known sauropod from England.^[1] Fossilized remains have been found in England and Morocco. Remains consisting of a vertebra, rib and arm bone had been discovered on the Isle of Wight and named by English biologist, comparative anatomist and palaeontologist Sir Richard Owen, in 1841, the year before he coined the term Dinosauria. More limb bones were found in the late 1840s and a fairly complete skeleton in 1868. Owen thought it had crocodilian features. Ironically, Cetiosaurus's true nature was not realized until Thomas Huxley named it as a dinosaur in 1869.^[2]

Illustration of Skeletal elements of C. oxoniensis

Cetiosaurus Species

• C. medius(type)
• C. brevis
• C. mogrebiensis Lapparent, 1955
• C. oxoniensis Phillips, 1871

Numerous species have been assigned to Cetiosaurus over the years and belong to several different groups of dinosaurs.^[3][4] The best known of these is C. oxoniensis, from the Middle Jurassic (Bajocian) of Oxfordshire and Rutland,^[5][3][4] However, the type species is C. medius, known from undiagnostic material^[4] (note that Upchurch and Martin [2003] reported C. brevis as the type species, but no longer hold this view;^[4] the problem stems from the fact that Richard Owen described four species in the same paper and did not designate one as the type). To improve this situation, Upchurch and colleagues have proposed making C. oxoniensis the type species of Cetiosaurus, which will retain the name Cetiosaurus for the animal with which it has been traditionally associated.^[4]

Classification

The closest relatives of Cetiosaurus appear to be Barapasaurus and the South American Patagosaurus. Together they comprise the Cetiosauridae, which was previously a large ill-defined family of primitive sauropods. It must also be noted that Chebsaurus is often referred to the Cetiosauridae, and that Barapasaurus has been assigned to the Vulcanodontidae, due to its having cervical vertebrae that resemble other cetiosaurids, but a narrow sacrum that is a defining factor for vulcanodontids.

Paleobiology

It shared its time period with, and was possibly prey to, Megalosaurus and Eustreptospondylus. The environment in which Cetiosaurus lived was floodplain and open woodland.

References

• Fastovsky DE, Weishampel DB (2005). "Sauropodomorpha:The Big, The Bizarre & The Majestic". In Fastovsky DE, Weishampel DB. The Evolution and Extinction of the Dinosaurs (2nd Edition). Cambridge University Press. pp. 229–264. ISBN 0-521-81172-4. 

1. ^ "Cetiosaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 65. ISBN 0-7853-0443-6.
2. ^ Debus AA (1994). "Mysterious Giants:Historical Sauropods". Dinosaur Report (Spring): 8–9. 
3. ^ ^{a b} Upchurch P & Martin J (2003). "The Anatomy and Taxonomy of Cetiosaurus (Saurischia, Sauropoda) from the Middle Jurassic of England". Journal of Vertebrate Palaeontology 23 (1): 208–231. doi:10.1671/0272-4634(2003)23[208:TAATOC]2.0.CO;2. 
4. ^ ^{a b c d e} Upchurch, P.; Martin, J.; and Taylor, M. (2009). "Case 3472: Cetiosaurus Owen, 1841 (Dinosauria, Sauropoda): proposed conservation of usage by designation of Cetiosaurus oxoniensis Phillips, 1871 as the type species" (pdf). Bulletin of Zoological Nomenclature 66 (1): 51–55. http://www.miketaylor.org.uk/dino/pubs/upchurch-et-al-2009/UpchurchEtAl2009-BZN-case-3472-cetiosaurus-type-species-oxoniensis.pdf. 
5. ^ Upchurch P & Martin J (2002). "The Rutland Cetiosaurus: the anatomy and relationships of a Middle Jurassic British sauropod dinosaur". Palaeontology 45 (6): 1049–1074. doi:10.1111/1475-4983.00275. 

• Online abstract of preceding article
• Lapparent, A. F. de 1955. E´ tude pale´ontologique des verte´bre´s du Jurassique d’El Mers (Moyen Atlas). Notes et Me´moires du Service Ge´ologique du Maroc 124:1–36.
• Melville, A. G. 1849. Notes on the vertebral column of Iguanodon. Philosophical Transactions of the Royal Society of London 139: 285–300.
• Owen, R. 1841. A description of a portion of the skeleton of the Cetiosaurus, a gigantic extinct

saurian reptile occurring in the oolitic formations of different portions of England. Proceedings of the Geological Society of London, 3: 457–462.

• Owen, R. 1842. Second rapport sur les reptiles fossiles de la Grande-Bretagne. L’Institut,

Journal général des Sociétés et Travaux Scientifique de la France et de l’ Étranger, 10: 11–14.

• Owen, R. 1842. Report on British fossil reptiles, Part II. Reports of the British Association for

the Advancement of Science, 11: 60–204.

• Owen, R. 1875. Monograph of the Mesozoic Reptilia, part 2: Monograph on the genus

Cetiosaurus. Palaeontolographical Society Monograph, 29: 27–43.

External links

• Cetiosaurus in the Dinosaur Encyclopedia at DinoRuss web site

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