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 (15-16 m) long and to have weighed roughly 24800 kg. 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.


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. 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.

Cetiosaurus oxoniensis, from the Middle Jurassic (Bajocian) of Oxfordshire and Rutland, also in England, is better known than the type species C. brevis and has been proposed by Upchurch to be the new type. They report the material of C. medius is insufficient to define Cetiosaurus and is hence a nomen dubium.

Cetiosaurus Species

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


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 shared its time period with, and was possibly prey to, Megalosaurus and Eustreptospondylus. Cetiosaurus's environment was floodplain and open woodland.



  • Fastovsky DE, Weishampel DB (2005). The Evolution and Extinction of the Dinosaurs (2nd Edition). Cambridge University Press. ISBN 0-521-81172-4.

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