Dilophosaurus wetherilli is an near the beginning Jurassic theropod dinosaur. It had paired curved crests on its skull, mostly likely for display. The actual dinosaur deliberate around 6 meters long and may have weighed half a ton. The fossils of Dilophosaurus come from the Navajo Indian Reservation, just west of Tuba City, Arizona. Remains were also established in Schenectady, New York. Just a few tens of feet below the level of the bones, large footprints of carnivorous dinosaurs are found, and these may fit in to Dilophosaurus. The unique description was published in 1954 by the renowned paleontologist Samuel Welles; however, at the time, it was thought to be another genus of theropod (Megalosaurus). In 1970, it was documented to be distinct and given its own generic name Dilophosaurus (meaning "two-crested lizard").
Welles later redescribed the entire taxon in 1984 in a much more total paper. Dilophosaurus may be a primitive member of the clade containing together ceratosaurian and tetanuran theropods. Alternatively, some paleontologists classify this genus as a large coelophysoid.
There is an additional species of Dilophosaurus (D. sinensis) which may or may not belong to this genus. It is possibly closer to the bizarre Antarctic theropod Cryolophosaurus, based on fact that the anterior end of the jugal does not contribute in the internal antorbital fenestra and that the maxillary tooth row is totally in front of the orbit and ends anterior to the vertical strut of the lacrimal. This species was recovered from the Yunnan Province of China in 1987 with the prosauropod Yunnanosaurus, and later described and named in 1993 by Shaojin Hu.
Dilophosaurus was also fitted in the 1993 movie Jurassic Park (and the book by Michael Crichton on which the film was based). It sported a retractable frill around its neck, much like a frilled lizard, and was clever to spit poison, aiming for the eyes to blind and paralyze its prey. There is no proof to support this representation. In the film, director Steven Spielberg also abridged its size, from moderately large to about 3 feet tall and 5 feet long - this was to keep rivalry low for the main star of the movie, Tyrannosaurus rex. Paleontologists, however, have exposed that Dilophosaurus had very weak mandibles, making it not possible for it to kill its prey by biting it without sustaining severe wounds (breaking of the jaw). This might be the basis for the theory of the poison, a way to debilitate its prey without putting itself at risk, which is in attendance in the book. The frill is possible, but no evidence has been found to hold up it.