Pachycephalosaurus — the thick-headed dinosaur of the late Cretaceous

When and where

Pachycephalosaurus lived during the Maastrichtian age of the Late Cretaceous, roughly 70 to 66 million years ago. Its fossils come from western North America, in the modern-day US states of Montana, South Dakota, and Wyoming, as well as the Canadian province of Alberta. The remains indicate a terrestrial plant-eater that inhabited the broad floodplains and coastal lowlands of the ancient Western Interior Seaway.

How we know

In 1931, Charles W. Gilmore named the genus from a domed skull found in Wyoming. The type species is P. wyomingensis. For decades, palaeontologists knew Pachycephalosaurus mainly from isolated skull roofs and partial crania, because complete skeletons remained scarce. Possible juvenile forms were once assigned to separate genera such as Stygimoloch; some researchers now regard these as growth stages of Pachycephalosaurus itself. Source: https://en.wikipedia.org/wiki/Pachycephalosaurus

What set it apart

Pachycephalosaurus is instantly recognizable for its extraordinarily thick, bony skull dome, which could reach up to 25 centimetres in thickness. Unlike most other dinosaurs, the top of its head was a solid dome of bone with small spikes and knobs at the rear. At roughly 4.5 metres long and an estimated 370–450 kilograms, it was one of the largest pachycephalosaurids. The function of the dome remains debated, but head-butting between rivals and flank-butting during display are both leading hypotheses.

For collectors and classrooms

A Pachycephalosaurus figurine is ideal for teaching cranial specialisation. The thick dome makes this genus unlike almost any other dinosaur replica on the shelf. Accurate models replicate the rounded skull profile and compact body that set it apart from the horned and long-necked groups most people picture first. Browse Pachycephalosaurus figures on Amazon