Small dinosaurs in the forests of North America had to watch out for the frightening form of Albertosaurus.
Albertosaurus was a fierce carnivorous dinosaur related to Tyrannosaurus. Although it was smaller than the latter, Albertosaurus probably ran faster on its long, powerful hind legs. It chased after herbivorous dinosaurs, or may have pounced on them while they grazed.
The earliest dinosaur remains to be found in Alberta, Canada, were Albertosaurus bones. They were found in 1884 by J.B. Tyrrell, after whom the world-famous dinosaur museum in Drumheller was named. It was one of the most abundant predators of the North American Cretaceous plains, and despite its great weight it was probably a fast runner, running down its prey, which would have consisted of duckbills.
Name: Albertosaurus, meaning ‘reptile from Alberta’
Size: 8.5-9m long
Food: meat, especially other dinosaurs
Lived: about 75 million years ago in Cretaceous Period in North America
Albertosaurus is very similar to its later cousin Tyrannosaurus, but is only about half the size. It is much better known as its remains are more numerous. Its skull is heavier, with smaller gaps in it surrounded by thicker struts of bone; the muzzle is longer and lower and also much wider; and the jaw is considerably shallower. The arms, although small, are a little larger than those of Tyrannosaurus.
When Albertosaurus attacked another dinosaur, its victim had little chance of escaping. Bitten and clawed, the victim was quickly overpowered and killed. The rear legs could deliver crushing blows, knocking the prey off balance. It could also deliver deadly wounds with its claws. The light build and long legs show that it was fast and graceful – it may have been able to run at speeds of up to 45km/h.
Albertosaurus had rows of backward-pointing, knife-like teeth in its huge mouth for tearing and chewing up meat. On each of its two feet there were three long, sharp claws and another smaller one. At the end of each of its short arms were two small claws. With these, Albertosaurus could grab and hold onto its prey – dinosaurs such as Edmontosaurus, Lambeosaurus and Chasmosaurus.