Category: Dinosaur

Ceratosaurus (See-rat-oh-sore-us), Strange Lizard lived in the Late Jurassic of North America. One of the earliest well-known theropods, Ceratosaurus was already highly specialized when it first appears in the fossil record, and is the largest ceratosaurid. It is regarded as a primitive carnosaur the relic from the first radiation of large predators of the Mesozoic. Smaller than the more common Allosaurus it could still have been dangerous to smaller plant eaters.



Genera and Species

Classification: Theropoda, Neoceratosasuria, Abelisaura

Species: C. nasicornis, C. dentisulcatus, C. magnicornis, C. ingens, C. meriani, C. stechowi.

Senior synonyms: Megalosaurus nasicornis, Labrosaurus sulcatus, Antrodemus sulcatus.


Ceratosaurus had had a median nasal horn and bony ridges over its eyes, and a row of small bony plates down its back. The tail is deep and heavy and could have made Ceratosaurus a better swimmer. The short legs mean it was not a fast predator. The arms are short and the teeth and head are large. The forearms have 4 fingers a primitive condition.


Length 4.5 - 6 m (15 - 20 ft).

Weight 0.5 - 1.2 tons.


It probably preyed upon the smaller camasaurs and diplodocids along with stegosaurs and camptosaurs. During the dry season fish were important food sources. There is fossil evidence that Allosaurus dined on Ceratosaurus which is rare except in the swampier parts of the Morrison.

History of Discovery

Discovered by Marsh in 1884. Known from 1 nearly complete adult skeleton, partial and complete skulls and skeletons.


Found in North America (Utah and Colorado USA) in semi arid plains with forested rivers with a short rainy season.


1. Paul, G. (2010). The Princeton Field Guide to Dinosaurs (pp. 10-12). Princeton, New Jersey: University Press Princeton.

2. Worth, G. (1999). The Dinosaur Encyclopaedia (pp. 615). Scarborough, Western Australia: HyperWorks Reference Software.