Ouranosaurus was an Early Cretaceous iguanodont hadrosauriform. It was unique because it had a hadrosaur-like bill and a sail on its back, like that Dimetrodon or Spinosaurus. This trait is not known in any other iguanodonts or hadrosauriforms besides Morelladon.

It was about 23 feet (7 m) long and may have weighed about 2 tons.



Ouranosaurus was 23 feet long and weighed 2 metric tons.[1] The femur is 811 millimetres long.


Ouranosaurus had a large ridge on its back, held up by long, wide, spines about a half a meter in length, that spanned its whole rump and tail, like that of Spinosaurus, a well-known meat-eating dinosaur that lived around the same time.[2] These tall spines did not look much like those of sail-backs such as Dimetrodon of the Permian Period. The supporting spines in a sailback get thinner distally, while in Ouranosaurus the spines get thicker distally and flatten. The rear spines were also bound together by ossified tendons, which made the back stiff. Finally, the spine length peaks over the forelimbs.

The sail could have been used to control body temperature or for display. Some think that the back might have had a hump, like that of a bison or camel, not a sail. It could have been used to store energy for a lean season.[3]


Ouranosaurus had a skull 67 cm long. The head was long and flat. Its snout was toothless and much longer than that of its relative Iguanodon.


Two almost complete Ouranosaurus fossils were found in the southern Sahara Desert, in northeast Niger, in 1966. Spinosaurus, a large, sail-backed meat-eater, was one of its contemporaries in the hot, Cretaceous environment of north Africa. Ouranosaurus was named by the French paleontologist Phillippe Taquet in 1976.


Taquet first assigned Ouranosaurus to the Iguanodontidae, in the larger Iguanodontia. But, while it shares some traits of Iguanodon (such as a thumb spike), Ouranosaurus is no longer placed in the iguanodontid family. It is now placed in the clade Hadrosauroidea, which contains the Hadrosauridae (aka "duck-billed dinosaurs") and their close relatives.


Ouranosaurus's wide mouth may mean that it ate a lot plants. It is not known if Ouranosaurus had key natural enemies. The large bumps on the head are a clue to a life in herds.

Ouranosaurus in The Land Before Time

It makes several appearances in The Land Before Time films. Many appear in later movies. Ouranosaurus first appears in The Land Before Time VII: The Stone of Cold Fire as part of the Far Walker herd, and also appears in the opening narration of The Land Before Time X: The Great Longneck Migration, walking behind a Styracosaurus.



  1. Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 292
  2. Palmer, D., ed (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 144. ISBN 1-84028-152-9. 
  3. Bailey, J.B. (1997). "Neural spine elongation in dinosaurs: sailbacks or buffalo-backs?". Journal of Paleontology 71: 1124-1146

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