Illustration of two Tyrannosaurus rex dinosaurs fighting. This bipedal theropod dinosaur was one of the largest ever predators, measuring over 12 metres in length from head to tail and weighing up to 8 tons. It is thought to have combined hunting and scavenging to feed itself. Its fossils are found in North America and date from around 67 million years ago, during the Cretaceous period. Often known as T-Rex. Two triceratops look on from a distance.