Stegoceras

*Stegoceras validum*

**Stegoceras** (Greek *for "roof horn"*) was a genus of ornithischian plant eating pachycephalosaurid dinosaur that was found in North America in the Late Cretaceous period 74-65 million years ago. It has an estimated length of 1.53 m (5 ft) and was 50 cm (19⅝ in) high at the hips and weighed 13 kg (28⅝ lb) which is quite small for a dinosaur. It was named by Lawrence Lambe in 1902.

Stegoceras' name means "roof horn" from the Greek words ***stegos/στέγος-*** "roof" or "covered" and ***kéras/κέρας*** -"horn".

*Stegoceras* sported a 5.1 centimeter (2 inch)-thick dome. It was initially proposed that male *Stegoceras* (and individuals of other pachycephalosaurid species) would ram each other headlong, not unlike contemporary bighorn sheepor musk oxen. It was later suggested that they engaged in flank-butting rather than ramming, a widely evidenced theory. Foremost, the rounded shape of the skull roof would lessen the contacted surface area during head-butting, resulting in glancing blows.

Second, pachycephalosaurs would not have been able to align their head, neck, and body in a perfect horizontal line (which would be needed to transmit stress) -- it was more likely that they carried their neck in an "S"- or "U"-shaped curve (*Stegoceras* seemed to carry their spine in a less extreme curve, due to their thick neck muscles).

Lastly, the relatively large width of most pachycephalosaurs would have served to protect vital organs from harm during flank-butting. When a partial skeleton of *Stegoceras* was first discovered, it was thought to have gastralia, or belly ribs, not typically found in other ornithischian dinosaurs. They were subsequently found to be ossified tendons.

## Description

*Stegoceras* had an estimated length of up to 2 metres (6.6 ft) and weighed 10 kilograms (22 lb) – 40 kilograms (88 lb). It had a relatively large brain that was encased in a dome of 3 inches (7.6 cm) of thick bone divided into two parts. The dome had a fairly smooth surface, but was irregularly pitted by foramina which gives an entrance to channels within the bone. *Stegoceras* (at least *S. validum*) can be distinguished by having a prominent parietosquamosal shelf with open supratemporal fosse, incipient doming of the frontopariental and minute node in clusters on postorbital and squamosals. *Stegoceras* had rounded eye sockets that faced forward, which suggests it had good vision and was thus capable of binocular vision. The teeth are small and curved with serrated edges. The head was supported by an "S"- or "U"-shaped neck. When a partial skeleton of *Stegoceras* was first discovered, it was thought to have gastralia, or belly ribs, not typically found in other ornithischian dinosaurs. They were subsequently found to be ossified tendons. The legs were more than three times the length of the arms.

## JPInstitute.com Description

Stegoceras was one of the smallest members of the same family that includes the more well known Pachycephalosaurus. It had a thick dome on its head, but instead of a ring of bumps or spikes, it had a small ridge of bone at the base of its dome. These were small, swift-running hunters who may have also eaten plants.

Discovered early in the 20th century, many subsequent dinosaurs were assigned to this genus and later reassigned. The genus is known from a complete skull, a number of partial skulls, and other skeletal material. To date, there is only one valid species for this genus. The skeletal remains of this dinosaur seem to support the theory of head butting for this family, which adds fuel to the debate over whether this activity would have been possible without injury to the spine.

## Appearance in other media

### *Jurassic Park*

* Stegoceras appears in *Jurassic World: Alive* as a Epic.

## Links

http://web.archive.org/web/20040214164638fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_steg.html