Stegoceras was a dome-headed, bipedal dinosaur. Its large head housed a thick skull, a relatively large brain, and large eyes. Its skull was about 3-4 inches (8 cm) thick. Males had thicker domes than females, and older Stegoceras had thicker domes than younger ones. Stegoceras had a fringe of horny knobs along the rear of its skull. It had short forelimbs and a large, stiff tail. Stegoceras grew to be about 7 feet long (2.1 m) and 4 feet tall (1.2 m).This plant-eater weighed roughly 170 pounds (78 kg).Stegoceras was a herding dinosaur that lived in small groups in coastal and upland regions. Running was probably its first line of defense.It had long been thought that Stegoceras' (and other pachycephalosaurs') thick dome may have been used for ramming rivals during mating and dominance combat, for attracting mates, and as a last-ditch defense against predators. Paleontologist Mark Goodwin of the University of California at Berkeley has analyzed many pachycephalosaur skulls (including those of Pachycephalosaurus), finding no evidence of healed scars. Also, under close analysis, the thick skull bone is not rigid and solid, but porous and fragile when put under extreme pressure. ``It's time to kill the myth.... It certainly wouldn't be in their own best interests to ram heads in a fight, said Goodwin. ``They would have killed each other, and a couple of bowling balls would hardly make good targets.
Stegoceras was an herbivore (a plant-eater, a primary consumer). It had small, curved teeth with serrated edges, a relatively large brain, and large eyes.Stegoceras lived during the late Cretaceous period, toward the end of the Mesozoic Era, the Age of Reptiles, about 76-65 million years ago. Among the contemporaries of Stegoceras were Albertosaurus and Maiasaura, Tyrannosaurus rex, Ankylosaurus (an armored herbivore), Parasaurolophus, Corythosaurus (a crested dinosaur), and Dryptosaurus (a meat-eating dinosaur).Stegoceras walked on two legs, and was a relatively speedy dinosaur. It may have gone on all fours to forage for plants.Stegoceras was first found and named in 1902 by Lawrence Lamb, the Canadian paleontologist, in 1889. Many Stegoceras and other pachycephalosaurid fossils have been found in Alberta, Canada, and Montana, USA. The type species is S. validum.