Stegoceras (horned roof)
Stegoceras (horned roof)
Named By : Lawrence Lambe - 1902
Diet : Herbivore
Size : Estimated 2 meters long
Type of Dinosaur : Euornithopod
Type Species : S. validum (type), S. novomexicanum
Found in : Canada, Alberta - Belly River Group and Saskatchewan - Judith River Formation. USA, Montana - Hell Creek Formation, Judith River Formation, and New Mexico - Fruitland Formation - Kirtland Formation.
When it Lived : Late Cretaceous, 76-74 million years ago
Stegoceras is the name of a species belonging to the pachycephalosaurid (dome-headed) dinosaurs which lived in the area that is today North America during the Late Cretaceous period, which was between 77.5 to 77.5 million years ago (mya). The first fossils of Alberta, Canada, were discovered in 1902 and the species that was named Stegoceras validum was named after the remains of these fossils. The generic name translates to “horn roof”, and the specific name translates to “strong”. There are a variety of species that have been included within the genus over time, but were later moved to different genera or considered minor synonyms. At present, there are only S. Validum as well as S. novomexicanum, named in 2011 based on fossils discovered within New Mexico, remain. The legitimacy of the latter species is also under debate.
Stegoceras was a small bipedal dinosaur that was between 2 and 2.5 meters (6.6 to 8.2 feet) long and weighed 10 to 40 kg (22 to 88 lbs). The skull was triangular, with a short snout and a wide broad, comparatively smooth dome at the top. The rear of the skull included a thick “shelf” over the occiput and an extensive ridge above the eyes. The skull was decorated by tubercles (or round “outgrowths”) and nodes (or “knobs”), numerous in rows. The largest were small horns that were placed in the shelves. The teeth were tiny and with serrated. The skull is believed to be flat during the juvenile stage and then grew to a dome as they grew older. It was characterized by a stiff vertebral column and stiffened tail. The pelvic region was large possibly because of the expanded gut.
At first, only known from skull-domes. Stegoceras was among the first known pachycephalosaurs and the incompletion of these first remains led to numerous theories on the affinities between this particular group. The complete Stegoceras skull, with the associated skeleton components was discovered in 1924, that shed new light on the animals. Pachycephalosaurs are now grouped together along with the Horned ceratopsians within the category of Marginocephalia. Stegoceras is considered the basal (or “primitive”) compared to other pachycephalosaurs. Stegoceras was likely to have been herbivore and likely had a keen sense of smell. The purpose of the dome is debatedand different theories are that it is used in intra-specific combat (head or side-butting) or sexual displays, or recognition of species. S. validum comes as belonging to the Dinosaur Park Formation and the Oldman Formation, whereas S. novomexicanum is from the Fruitland and Kirtland Formation.