Dilophosaurus
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? Dilophosaurus Conservation status: Fossil
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 Dilophosaurus animatronic model
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| Dilophosaurus wetherilli Welles, 1970 |
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Dilophosaurus wetherilli (dy-LOH-fo-sawr-us) meaning "two-crested lizard", because it had two crests ( Greek di = two + lophos = crest + sauros = lizard) was an early Jurassic theropod dinosaur.
Description
Dilophosaurus measured around 6 meters (20 ft) long and may have weighed half a ton. Its fossils of come from the Navajo Indian Reservation, just west of Tuba City, Arizona. Just a few tens of feet below the level of the bones, large footprints of carnivorous dinosaurs were found, and these may belong to Dilophosaurus.
The original 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 recognized 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 complete paper. Dilophosaurus may be a primitive member of the clade containing both ceratosaurian and tetanuran theropods. Alternatively, some paleontologists classify this genus as a large coelophysoid. Recent Dilophosaurus "skin imprints" associated with a set of footprints seemed to suggest that it had feathers, but further study revealed these to be impressions of plant material.
Skull and crests
The most distinctive characteristic of Dilophosaurus was the pair of rounded crests on its skull, probably used for display. Studies by Rob Gay (2001) show that these crests may have been larger in one sex and smaller in the other. Another curious feature in the skull of Dilophosaurus was a notch behind the first row of teeth, giving it an almost crocodile-like appearance.
Dilophosaurus is thought by some to be a scavenger because of its relatively weak jaws and sensitive crests. Others think that it was an active predator, running down its prey, and tearing into them with its sharp claws. Once it had its prey on the ground, it could finish it off with one blow of its sharply clawed foot. It could then rip open the carcass, and use its large teeth to take out chunks of meat.
Species
There is another 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 the fact that the anterior end of the 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. 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.
In popular culture
Dilophosaurus was included 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 able to spit poison, aiming for the eyes to blind and paralyse its prey. There is no evidence to support this representation. In the film, director Steven Spielberg also reduced its size, from moderately large to about 3 feet tall and 5 feet long - this was to keep competition low for the main star of the movie, Tyrannosaurus rex. However, the reduced size can be explained as assuming the Dilophosaurus depicted was young.