Pachycephalosaurus

Main Group: Marginocephalian Dinosaurs

Time: Late Cretaceous

Size: 16 1/2 ft (5 m) long

Fossil Finds: North America



Of the group of dinosaurs known as pachycephalosaurs ("Bone Headed Dinosaurs"), Pachycephalosaurus was the largest. Two other pachycephalosaurian species, Dracorex and Stygimoloch are now considered different growth stages of Pachycephalosaurus.