The Triceratops is the state dinosaur of Wyoming. The Triceratops is the state fossil of South Dakota. Tyrannosaurs were notoriously vicious hunters that ruled the Cretaceous with their ferocious jaws and cunning pack hunting behavior.
It may have been one of the most common dinosaurs in the North American West at the time of Tyrannosaurus rex. These dinosaurs are often pictured traveling in large groups, but the biggest gathering of Triceratops ever found consisted of three youngsters.