Edmontosaurus was a hadrosaur from the Cretaceous. It was one of the last non-avian dinosaurs on Earth before the mass extinction event. It was 12 meters (40 ft) and 3 1/2 tons. Edmontosaurus was a large hadrosaur. It had very large and wide hind legs and its front legs were short and chunky. Edmontosaurus had a large bill that resembled that of a modern duck. Inside its mouth was a large battery of teeth, designed to grind vegetation. Despite its relatively large size, Edmontosaurus was preyed upon by the North American apex predator, Tyrannosaurus rex. However, although it had very few weapons of choice, it had the ability to run rather quickly. Like its ancestors, it could run on its hind legs. However, its speed doesn't always guaranteed it safety.
In the late Cretaceous segment, the Edmontosaurus(identified as Anatotitan) are first seen living with Triceratops and Ornithomimus. The next morning, a pack of T. rex hunt the hadrosaurs. A young male chases them into the trap with his larger siblings coming out, surprising three Edmontosaurus. Soon the mother attacks and kills one of them.