Dilophosaurus
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 Reconstruction of Dilophosaurus wetherelli
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Extinct (fossil)
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Dilophosaurus was a theropod dinosaur from the Early Jurassic Period. The name is pronounced (dy-LOH-fo-sawr-us) meaning 'two-crested lizard', because it had two crests (Greek di meaning 'two', lophos meaning 'crest' and sauros meaning 'lizard')
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[edit] Description
Dilophosaurus measured around 6 meters (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.
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.
[edit] 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 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 also present in another Ceratosaur, Syntarsus.
[edit] 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.
[edit] In popular culture
- Dilophosaurus 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 spit poison, aiming for the eyes to blind and paralyse its prey. There is no evidence to support this representation, which was invented by the author and director to heighten suspense. 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 .
- 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.
- Dilophosaurus featured in the documentary When Dinosaurs Roamed America, killing an Anchisaurus and scaring off a pack of Megapnosaurus.
- Dilophosaurus was also featured in the Vivendi Universal game Jurassic Park: Operation Genesis.
- Dilophosaurus has been featured in the arcade games of The Lost World: Jurassic Park and Jurassic Park III but did not appear in the movies.
- The Dilophosaurus in the ParaWorld PC game resembles the one from Jurassic Park.
[edit] References
- Gay, R. (2001). "Evidence for sexual dimorphism in the Early Jurassic theropod dinosaur, Dilophosaurus and a comparison with other related forms". Journal of Vertebrate Paleontology 21(3): 53A.
- Gay, R. (2001). "New specimens of Dilophosaurus wetherilli (Dinosauria: Theropoda) from the early Jurassic Kayenta Formation of northern Arizona". Western Association of Vertebrate Paleontologists annual meeting volume Mesa, Arizona.
- Hu, Shaojin (1993). "A note on a double-crested dragon (Dilophosaurus) fossil discovered in Jinning County, Yunnan Province." Gu Jizhui Dongwu Xuebao = Vertebr. PalAsiatica, 31 i.
- Welles, S. P. (1954). "New Jurassic dinosaur from the Kayenta formation of Arizona". Bulletin of the Geological Society of America 65: 591-598.
- Welles, S. P. (1984). "Dilophosaurus wetherilli (Dinosauria, Theropoda), osteology and comparisons." Palaeontogr. Abt. A: Paläozool., Stratigr., 185, 85-180.
