Temporal range: Early Jurassic
|An artist's interpretation of Dilophosaurus wetherilli|
| †Dilophosaurus wetherilli|
Dilophosaurus (di·loph·o·saur·us) (Double Crested Lizard) was the very first large carnivorous dinosaur of North America. It is distinctly known from its two famous crests rounding above its skull. Its fossils were uncovered in Southwestern US and possibly China. Although primitive in the terms of Tyrannosaurus rex or Allosaurus, it was actually a very advanced predator at its time, (the early Jurassic time period).
Dilophosaurus measured around 6 metres (20 ft) long and may have weighed half a ton. Fossils of the animal have been found at the Navajo Indian Reservation, just west of Tuba City, Arizona, USA. 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. It lived in the Early Jurassic Period, more primitive than later carnivores of the Jurassic, such as Ceratosaurus or Allosaurus.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. Welles later redescribed the entire taxon in 1984, in a more comprehensive 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.
Footprints of Dilophosaurus have been discovered in the Lavini di Marco area, near Rovereto (Trentino, northern Italy). They are associated with those of Camptosaurus.
Skull and CrestsEditThe 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 than in the other. Another curious skull feature was a notch behind the first row of teeth, giving it an almost crocodile-like appearance. This "notch" existed by virtue of a weak connection between the premaxillary and maxillary bones of the skull. This conformation led to the early hypothesis that Dilophosaurus scavenged off dead carcasses, with the front teeth being too weak to bring down and hold large prey. A similar notch is present in most other species of coelophysoid.
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.
Popular Culture EditDilophosaurus was featured in the 1993 movie Jurassic Park and in the original novel by Michael Crichton (on which the film was based). In the film version, it had a retractable frill around its neck, much like a frilled lizard, and was able to shoot venom, like a spitting cobra, aiming for the eyes to blind and paralyze its prey. There is no true fossil evidence to support this representation, which was invented by the author and director to heighten suspense. However, this is explained by saying that this was due to genetic tampering with spitting cobra and Austrailian frilled lizard DNA. In the film the director Steven Spielberg reduced its size, from moderately large to about 3 feet tall and 5 feet long - this was so as not to overshadow the main star of the movie, Tyrannosaurus rex. In the novel, the creature was 10 feet tall with no frill and had poisonous saliva that was used in predation by biting or spitting at its prey. In the novel, this trait was discovered by the researchers at Jurassic Park, who planned to remove the glands containing the poison. This plan was not carried out - an autopsy would have been needed to see how to remove the glands, but it would have required killing a Dilophosaurus, which John Hammond, owner of the park, opposed. Jurassic Park merchandise, including toys and video games (such as Jurassic Park: Operation Genesis and the arcade games The Lost World: Jurassic Park and Jurassic Park III), often include Dilophosaurus. Other video games, ParaWorld, Jurassic The Hunted, and Ice Age Dawn of the Dinosaurs feature Dilophosaurus modelled after the one in Jurassic Park. It can be also created from DNA in Jurassic Park: Builder as well. It also makes an appearance in Turok, where it is more accurately sized than the one in Jurassic Park.