Dinosaurs · Pachycephalosaur

Stegoceras

Say it ste-GOS-er-as. The name means ‘horny roof’.

Stegoceras beside a person 1.75 m tall. Ticks mark every metre.Body shape drawn for this site, showing the general build of pachycephalosaurs

Length: 2.4 m
Diet: Plant-eater
When: Late Cretaceous76 to 74 million years ago
Fossils found in: Canada, USA
Named by: Lambe (1902)
Family tree: Dinosauria › Ornithischia › Neornithischia › Cerapoda › Marginocephalia › Pachycephalosauria › Pachycephalosauridae

Where Stegoceras sits in the age of dinosaurs.Periods from the ICS chart; dinosaur dates from the Natural History Museum

Pachycephalosaurs. Two-legged plant-eaters with thick, domed skulls. See all 8

Lived at the same time

Achelousaurus · same country
Albertosaurus · same country
Bambiraptor · same country
Centrosaurus · same country
Chasmosaurus · same country
Chirostenotes · same country
Corythosaurus · same country
Daspletosaurus · same country

Other pachycephalosaurs

Tylocephale Late Cretaceous
Homalocephale Late Cretaceous
Prenocephale Late Cretaceous
Goyocephale Late Cretaceous
Pachycephalosaurus Late Cretaceous
Stygimoloch Late Cretaceous
Dracorex Late Cretaceous

Source: Stegoceras in the Natural History Museum Dino Directory, read 12 November 2026. Sizes are the museum's estimates for a typical adult. "Lived at the same time" lists dinosaurs whose dates overlap, which does not always mean they met.