Tyrannosaurus rex is the one dinosaur that everyone knows. What is often forgotten is that it is also one of the rarest. Predators at the top of the food-chain are much fewer in number that the animals they prey on. It was also one of the last of the dinosaurs. It lived late in the Cretaceous period and by the end of that period all dinosaurs were extinct.
Tyrannosaurus bones come from the American Mid-West but very similar fossils found elsewhere have been given different names. The late Cretaceous sediments of Canada yield Albertosaurus, those of Mongolia Tarbosaurus. They all walked on powerful hind-legs and had tiny two-toed forefeet. They had large skulls with a predator's pointed teeth. One difference is in the position of the eyes - those of Tyrannosaurus looked forward giving it bifocal vision. Tarbosaurus, by contrast, had eyes on the side of its head.