Post by Super Communist on Nov 4, 2011 20:38:31 GMT -5
Dilophosaurus measured around six meters (20 ft) long and may have weighed half a ton.
The most distinctive characteristic of Dilophosaurus is the pair of rounded crests on its skull, possibly used for display. Studies by Robert Gay show no indication that sexual dimorphism was present in the skeleton of Dilophosaurus, but says nothing about crest variation. The teeth of Dilophosaurus are long, but have a fairly small base and expand basally. Another skull feature was a notch behind the first row of teeth, giving Dilophosaurus an almost crocodile-like appearance, similar to the putatively piscivorous spinosaurid dinosaurs. 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.
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It was 2.5 metres (8 ft 2 in) tall and weighed approximately 150 kilograms (330 lb), but with large variance (perhaps indicating strong sexual dimorphism). Though its skull has not been found, it most probably would have been large, with a huge, axe-like beak, like its relatives.
The wings were small and could not have been used for flight. The wing bones articulated in an unusual joint-like structure, suggesting the digits could flex to some degree. It also had a relatively rigid wrist, which would not have allowed the hand to fold back against the arm to the same degree as other birds. This led one scientist, R.M. Chandler, to suggest that the wings may have supported some type of clawed, mobile hand similar to the hands of non-avian theropod dinosaurs, such as the deinonychosaurs (also popularly known as "raptors") . However, it was later pointed out that this wing joint is not in fact unique, and is present in seriamas (modern members of the same bird group to which Titanis belonged), which do not have any specialized grasping hands.
Overall, Titanis was very similar to the South American Phorusrhacos and Devincenzia, its closest relatives. However, it differs from these in having a shorter, thicker neck, a bulkier head, and an overall more heavily-built bodily structure. Little is known of its body structure, but it seems to have been less wide-footed than Devincenzia, with a proportionally much stronger middle toe.[11] (Onactornis is now considered a junior synonym of Devincenzia).
