Family Megalosauridae

The earliest well-known carnosaurs belong to this family of "great lizards." Their remains have been found in North America, Africa and Europe, and as a group they span a period of 140 million years — from the Early Jurassic to the end of the Cretaceous.

All were massively built, big-boned .creatures. The large head was high and narrow, equipped with powerful jaws and many sharp, saw-edged teeth. The arms were short but strong. The legs were long and massive enough to support the great body weight on the 3 spreading, clawed toes of each foot (a tiny fourth toe was also present), yet light enough to allow the creature to amble along quite quickly.

name: Teratosaurus time: Late Triassic locality: Europe (Germany) size: 20 ft/6 m long

This is a puzzling beast among the dinosaurs. Erom fragments of its skeleton, mostly teeth, paleontologists have tentatively constructed a picture of Ter-atosaurus as a primitive carnosaur.

It was a large, 2-legged creature, with a heavy head and many sharp, curved teeth. Its body was also heavy, with a short neck and long, stiffened tail. Sturdy legs ended in 3 powerful, clawed toes, for walking and ripping flesh. (A fourth toe was present, but it was tiny.) The short, strong arms had grasping fingers with curved claws.

Erom the remains of Teratosaurus, and fragments of related beasts found in southern Africa, some paleontologists postulate that a group of large, meat-

eating theropods may have existed some 60 million years before the main stock of carnosaurs appeared, in Early Jurassic times. Teratosaurus may, therefore, be the earliest-known relative of the megalosaur family.

However, other paleontologists reckon that it may be an early member of the prosauropod group of dinosaurs (see pp. 122-125) or even a large representative of the thecodontians, from which group arose the ancestors of the dinosaurs (see pp. 94—97).

name: Proceratosaurus time: Middle Jurassic locality: Europe (England) size: 16 ft/5 m long

This early carnosaur is known only from a single skull. Although it is longer than average, the skull shows the same general features as other primitive carnosaurs. But there is one atypical feature — a small horn above the snout. This suggests that this creature may have been an ancestor, or even an early member, of the ceratosaurs — those carnosaurs characterized by a nose horn (see p. 117).

The restoration on p. 114 shows Proceratosaurus as a typical carnosaur — large head, short neck, heavy body, long tail, short arms with clawed fingers, and long running legs each with 3 toes.

name: Dilophosaurus time: Early Jurassic locality: North America (Arizona) size: 20 ft/6 m long

First discovered in 1942 by an expedition from the University of California, Dilophosaurus seems to have been a lightly built carnosaur. This sounds like a contradiction, but it was intermediate in structure between the 2 groups. Its head was large (a typical carnosaur feature) but lightboned, while its neck, tail and arms were long and slender (typical coelurosaur features, see pp. 106—113).

The skull of Dilophosaurus was unusual for any group. A pair of semicircular, bony crests rose vertically on either side of the skull. Although wafer-thin in places, they were strengthened by vertical struts of bone. At the back of the head, the tip of each crest narrowed into a spike.

The function of these head crests remains a mystery. Some paleontologists think that they could have been sexual display structures, and that only the males had them — a theory supported by the fact that not all specimens found had the crests. Indeed, there were none on the first few skeletons unearthed, and the animals were thought to have been a species of Megalosaurus (below). The crests have never been eustreptospondylus

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