Pachycephalosaurus fossil map
Where fossils of Pachycephalosaurus have been found, shown on the Earth as it looked about 66 million years ago and on today’s map.
Dots are fossil collections recorded in the Paleobiology Database. The “then” view moves today’s fossil sites back to their positions 66 million years ago (the time slice nearest the median age of the fossils) using the Merdith et al. (2021) plate model; positions are approximate. Open on the timeline map →
| Group | Horned & dome-headed dinosaurs |
|---|---|
| Lived | 83.6–66 million years ago (Campanian to Maastrichtian) |
| Periods | Cretaceous |
| Named by | Brown and Schlaikjer 1943 |
| Fossil records | 34 occurrences at 31 locations (PBDB) |
| Found in | United States, Canada |
| Rock formations | Hell Creek, Lance, Ferris, Denver, Dinosaur Park, Scollard |
About Pachycephalosaurus
Pachycephalosaurus is a genus of pachycephalosaurid ornithischian dinosaur. The type species, P. wyomingensis, is the only known definitive species. It was among the last species of non-avian dinosaurs on Earth before the Cretaceous–Paleogene extinction event, which lived during the Maastrichtian age of the Late Cretaceous period in what is now western North America. Remains have been excavated in Montana, South Dakota, Wyoming, and Alberta. Mainly known from a single skull and a few extremely thick skull roofs (at 22 cm (8.7 in) thick), Pachycephalosaurus is estimated to have reached 4.5 m (15 ft) long and weighed 370–450 kg (820–990 lb). More complete fossils would come to be found in the following years.
Text in “About” is quoted from the Wikipedia article Pachycephalosaurus (revision 1378367704), licensed under CC BY-SA 4.0; introduction excerpted verbatim, formatting removed. Ages, family, authority and fossil records: Paleobiology Database, accessed 22 October 2026. Ages are those of the rock layers the fossils were found in. Wikidata: Q14455.
