Ceratosaurus was a large theropod dinosaur. It possessed an unusual configuration of hornlets over its eyes, and a blade-shaped horn on its snout. Its name means 'horned lizard'. An unusual feature of Ceratosaurus was the dermal armor in the middle of its back.
Ceratosaurus was found in the Cleveland Lloyd Dinosaur Quarry in Utah, and from the Dry Mesa Quarry in Colorado. It was first described in 1884. Later finds occurred in Portugal, as well as fragments in the Morrison Formation.
The Cleveland Lloyd Dinosaur Quarry is a mudstone site on the floodplain for a river system. The Dry Mesa Quarry site appears to have been a mass grave as a result of a drought, followed by a flash flood.