Dilophosaurus

Dilophosaurus (Early Jurassic) was a theropod dinosaur. It had paired rounded crests on its skull, mostly likely for display. It measured around 6 meters from the tip of the snout to its tail and may have weighed nearly half a ton. This dinosaur has only been discovered in Arizona (U.S.A.). The original description was published in 1954 by the renowned paleontologist Samuel Welles, however, at the time, it was referred to another genus of theropod (Megalosaurus). In 1970, it was recognized to be quite distinct and given its own generic name Dilophosaurus (meaning "two-crested lizard"). Welles later redescribed the entire taxon in 1984 in a much more complete paper. It may be a primitive member of the clade containing both ceratosaurian and tetanuran theropods.

There is another species of Dilophosaurus (D. sinensis) which may or may not belong to this genus (possibly closer to the bizarre Antarctic theropod Cryolophosaurus, based on the anterior end of jugal does not participate in the internal antorbital fenestra and that the maxillary tooth row is completely in front of the orbit and ends anterior to the vertical strut of the lacrimal). It was recovered from the Yunnan Province of China in 1987 with the prosauropod Yunnanosaurus, and later described and named in 1993 by Shaojin Hu.