Dilophosaurus

***Dilophosaurus*** ***(DI·loaf·o·SORE·us)*** (Greek, "double crested lizard") was the first large carnivorous dinosaur to appear in North America during the early Jurassic period. 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.

## Description

*Dilophosaurus* measured around 6 metres (20 feet) long and may have weighed around a ton. Fossils of the animal have been found at the Navajo Indian Reservation, just west of Tuba City, Arizona, USA and in the Kayenta Formation. 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, from the Sinemurian to the Pliensbachian stages (193-183 million years ago), and was 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 a *Dilophosaurus-*like predator have been discovered in the Lavini di Marco area, near Rovereto (Trentino, northern Italy).

Meanwhile the Dilophosaurus true diet is unknown; it is assumed that the animal had probably a mixed diet of both terrestrial and aquatic prey; similiar to spinosaurids, as its speculated to be large enough to hunt large prosauropods as well as smaller dinosaurs including the local species of coelophysis (*C. kayentakae*) and *Sarahsaurus*. Latter research also concluded the possiblity of fish-hunting on rivers and delta's. [1]

The Latest Research has reinstated the the dinosaur to being a potential macropredator [2]

## 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 present in most other species of coelophysoid.

## 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.