Pachycephalosaurus, meaning "thick-headed lizard" was a herbivore that walked on 2 legs. It is well-known for the huge 10 inch (25cm) thick bony dome on top of its skull, which was used to cushion its brain whilst the males fought. They fought for females by charging at each other and clashing their heads together at speed. The huge skull protected the brain. It lived in the Late Cretaceous, about 70-65mya in what is now North America. It died out in the K-T extinction.
Fact File
Height = 2m
Length = 4m
Weight = 2 tonnes
Diet = Herbivorous
Prey
Not much is known about Pachycephalosaurus's eating habits and what ate it, but the chances are that it was sometimes eaten by T-Rex, and like most dinosaurs, its carcasses were very often scavenged.