世界共通発音：ステゴセラス steg o ser as
Ornithischia / Genaria / Cerapoda / Marginocephalia / Pachycephalosauria /
Family: Pachycephalosauridae /
FIRST DESCRIBED: 1902 / FOUND: North America: Canada /
LENGTH: 2.5 m / WEIGHT: 70 kg /
FOOD: Plants / YOUNG: Eggs / LIVED: Late Cretaceous 76 68 million years ago
Stegoceras is a member of the same family as Pachycephalosaurus, the 'Thick headed Lizard', but it was only one third the size of its giant cousin. One of the main family characteristics was the greatly thickened roof of the skull. Scientists have debated why the skull was thickened, and most think that males fought one another over territory.
The larger the male and the thicker his skull, the stronger and more mature he was. Numerous skulls of Stegoceras have been discovered and they show a range of ages, the older animals having the thickest skull roofs. Modern day mountain sheep and goats have a similar skull thickening. It is likely that Stegoceras lived in upland areas.
Only one poorly preserved skele¬ton has been discovered, and the evidence suggests that Stegoceras was quite lightly built, with short arms and strong legs. Compared to some theropods, the hands and feet of Stegoceras were quite primitive. The hands have five fingers, whereas the feet have three moderately long toes and an inner toe that is reduced to just a spur.