For the stegosaur of a similar name, see Stegosaurus.
Stegoceras
Temporal range: Late Cretaceous, ~77.5–74 Ma
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Two reconstructed S. validum skeletons based on specimen UALVP 2, Royal Tyrrell Museum
Scientific classification
Domain:
Eukaryota
Kingdom:
Animalia
Phylum:
Chordata
Clade:
Dinosauria
Clade:
†Ornithischia
Clade:
†Pachycephalosauria
Family:
†Pachycephalosauridae
Genus:
†Stegoceras Lambe, 1902
Type species
†Stegoceras validum
Lambe, 1902
Species
†S. validum Lambe, 1902
†?S. novomexicanum Jasinski & Sullivan, 2011
Synonyms
List
Stegoceras validus Lambe, 1902
Troodon validus Gilmore, 1924
Stegoceras browni Wall & Galton, 1979
Ornatotholus browni Galton & Sues, 1983
?Gravitholus albertae Wall & Galton, 1979
?Hanssuesia sternbergi Brown & Schlaikjer, 1943
Stegoceras is a genus of pachycephalosaurid (dome-headed) dinosaur that lived in what is now North America during the Late Cretaceous period, about 77.5 to 74 million years ago (mya). The first specimens from Alberta, Canada, were described in 1902, and the type species Stegoceras validum was based on these remains. The generic name means "horn roof", and the specific name means "strong". Several other species have been placed in the genus over the years, but these have since been moved to other genera or deemed junior synonyms. Currently only S. validum and S. novomexicanum, named in 2011 from fossils found in New Mexico, remain. The validity of the latter species has also been debated.
Stegoceras was a small, bipedal dinosaur about 2 to 2.5 metres (6.6 to 8.2 ft) long, and weighed around 10 to 40 kilograms (22 to 88 lb). The skull was roughly triangular with a short snout, and had a thick, broad, and relatively smooth dome on the top. The back of the skull had a thick "shelf" over the occiput, and it had a thick ridge over the eyes. Much of the skull was ornamented by tubercles (or round "outgrowths") and nodes (or "knobs"), many in rows, and the largest formed small horns on the shelf. The teeth were small and serrated. The skull is thought to have been flat in juvenile animals and to have grown into a dome with age. It had a rigid vertebral column, and a stiffened tail. The pelvic region was broad, perhaps due to an extended gut.
Originally known only from skull domes, Stegoceras was one of the first known pachycephalosaurs, and the incompleteness of these initial remains led to many theories about the affinities of this group. A complete Stegoceras skull with associated parts of the skeleton was described in 1924, which shed more light on these animals. Pachycephalosaurs are today grouped with the horned ceratopsians in the group Marginocephalia. Stegoceras itself has been considered basal (or "primitive") compared to other pachycephalosaurs. Stegoceras was most likely herbivorous, and it probably had a good sense of smell. The function of the dome has been debated, and competing theories include use in intra-specific combat (head or flank-butting), sexual display, or species recognition. S. validum is known from the Dinosaur Park Formation and the Oldman Formation, whereas S. novomexicanum is from the Fruitland and Kirtland Formation.
group Marginocephalia. Stegoceras itself has been considered basal (or "primitive") compared to other pachycephalosaurs. Stegoceras was most likely herbivorous...
in south Alberta. In 1945, it was transferred to Stegoceras by C.M. Sternberg himself, as a Stegoceras sternbergi. The genus Hanssuesia was first named...
Pachycephalosauridae to include only "dome-skulled" species (including Stegoceras and Pachycephalosaurus), while leaving more "basal" species outside that...
paleontologists thought that Troodon, then known only from teeth, was the same as Stegoceras, which had similar teeth. Accordingly, what are now known as pachycephalosaurids...
dome allows Foraminacephale to be differentiated further from Stegoceras. In young Stegoceras, the dome is flat; however, in even the smallest Foraminacephale...
dinosaurs, Stegoceras lambei, n. sp., described. Journal of Paleontology 19(5):534-538 Sullivan, R. M. (2003). "Revision of the dinosaur Stegoceras Lambe (Ornithischia...
and tall hind legs. The head of Prenocephale was comparable to that of Stegoceras, albeit with closed supratemporal fenestrae. Also, the paired grooves...
species of the genus Troodon in 1953, and later transferred to the genus Stegoceras. After decades of being considered dubious, it was re-evaluated in 2021...
buchholtzae by the elongate parietals. It was once considered a species of Stegoceras and was about the same size, reaching 2 m (6.6 ft) in length and 40 kg...
that the tooth belonged to the herbivorous pachycephalosaur Stegoceras and that Stegoceras was in fact a junior synonym of Troodon. The similarity of troodontid...
whether the animal represents a distinct genus, or if it is synonymous with Stegoceras. Some recent publications indicate it may be a valid genus. Gravitholus...
similar if not greater than more derived pachycephalosaur. Compared to Stegoceras validum and later Campanian pachycephalosaurids, the dorsally convex frontonasal...
M. (1945). "Pachycephalosauridae Proposed for Dome-Headed Dinosaurs, Stegoceras lambei, n. sp., Described". Journal of Paleontology. 19 (5): 534–538....
were the ceratopsian Pentaceratops sternbergii; the pachycephalosaur Stegoceras novomexicanum; and some unidentified fossils belonging to Tyrannosauridae...
saw some pachycephalosaur skulls as indicative for a taxon in between Stegoceras and Pachycephalosaurus; these have not been consistently referred to a...
in their 1943 hypothesis that Stegoceras validum exhibited sexual dimorphism. Under Galton's interpretation, as Stegoceras grew the dome expanded until...
been found, though there are well-preserved skeletons of the related Stegoceras, Homalocephale, and Prenocephale. Based on these taxa, Alaskacephale had...
present with dimorphic features, many doubt the validity of these claims. Stegoceras validum, a pachycephalosaur, can be segregated into two groups based on...
the contemporary pachycephalosaur Stegoceras suggest that Thescelosaurus was a selective feeder, while Stegoceras was a more indiscriminate feeder, allowing...
occipital region of Stegoceras was well-demarcated for muscle-attachment and it is believed that the jaw movement of Stegoceras and other pachycephalosaurs...
Ornitholestes on display Prosaurolophus on display Sinraptor dongi on display Two Stegoceras on display Triceratops on display Tyrannosaurus on display Jurassic section...
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