No dinosaur has captured public attention so much as the awesome Tyrannosaurus rex (Figs. 85c, 94,122) from North America. Coprolites (fossilised faeces) containing the shattered bones of herbivorous dinosaurs suggest that Tyrannosaurus crushed food in its powerful jaws before swallowing it. Less well known is Gigantosaurus (Fig. 125), also of the family Tyrannosauridae, from the Upper Cretaceous of Patagonia, and significantly larger. Carcharo-dontosaurus from North Africa was another huge bipedal flesh-eater (length ca. 8 m), but it was lightly built with a large head and shark-like fangs. Its relationships, however, are uncertain and it could possibly have been related to the

■ Fig. 125. Gigantosaurus (Tyrannosauridae; Upper Cretaceous; length ca. 14 m) attacking a hadrosaurid (length ca. 9 m)

Compsognathidae (Sect. 11.3.1) rather than to the Tyrannosauridae. Unlike Iguanodon, however, which walked on all fours, the giant carnosaurs would have walked and run bipedally, their bodies almost horizontal and balanced by the heavy tail (Figs. 124,125). Another gigantic Upper Cretaceous tyrannosaurid was Tarbosaurus from Mongolia (length ca. 14 m). It could have preyed on the hadrosaurs and armoured dinosaurs that lived in the same environment. It was somewhat more lightly built than Tyrannosaurus, but had a longer skull.

Smaller tyrannosaurids included Albertosaurus (length ca. 8 m) and Dasple-tosaurus (length ca. 8.5 m) from North America, and Alioramus (length ca. 6 m) from Mongolia. Albertosaurus differed from the other tyrannosaurids in being much more lightly built, but its lifestyle was probably very similar. The different genera must have evolved in different places or at different times during the Upper Cretaceous - which lasted for nearly 35 my, allowing ample opportunities for such changes to have occurred.

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