Pachicephalosaurus

Description
Pachycephalosaurus was a medium-sized herbivorous dinosaur that lived in the late Cretaceous period, 89 to 75 million years ago, in North America. They are famous as "bone-head" dinosaurs, due to the 10-inch thick rounded plate of bone in their foreheads. Contrary to popular belief, Pachycephalosaurus probably did not butt heads with each other. The Pachicephalosaurus use his hard heads to protect from predators.