Outline: a typical pachycephalosaur
Brontotholus
"thunder dome"
Type species Brontotholus harmoni
- Lived
- 84 to 72 million years ago, Late Cretaceous
- Diet
- Herbivore
- Group
- Pachycephalosaurs, Pachycephalosauridae
- Found in
- United States and Canada
- Named by
- Woodruff et al. 2025
Where its fossils were found
The evidence
Today
80 million years ago
Field notes
About Brontotholus
What it was like
Brontotholus was a pachycephalosaur, a plant eater that walked on two legs and had a thick, rounded dome of bone on top of its skull. It is known from several domes, which were larger than those of most of its relatives.
Its world
It lived in the Late Cretaceous, in what is now Montana and Alberta. It comes from the Two Medicine and Oldman formations, where it shared the land with the tyrannosaur Daspletosaurus, the duckbills Corythosaurus and Hypacrosaurus, and the armored Euoplocephalus.
How it was found
Woodruff and colleagues named Brontotholus in 2025. The type species is Brontotholus harmoni.
Lived alongside
Found in the same rock formations
Close relatives
Other members of Pachycephalosauridae
Sources: WikidataNamed in: D. C. Woodruff, J. R. Horner, and M. B. Goodwin, D. C. Evans. 2025. The first pachycephalosaurid from the Late Cretaceous Two Medicine Formation: effects of the Western Interior Seaway on North American pachycephalosaurid evolution. Zoological Journal of the Linnean Society 205(2):zlaf087