Brontotholus harmoni Brontotholus

"thunder dome"

You 1.8 m (5.9 ft) tall
Brontotholus 3.8 m (12.5 ft) long
3 people holding hands
Length
3.8 m (12.5 ft)
Period
Late Cretaceous (75.5–75.3 Mya)
Place
United States · Canada · Alberta, Canada · Montana, USA
Food
Herbivore
Clade
Pachycephalosauridae Dinosauria Ornithischia Cerapoda Marginocephalia

Brontotholus (“thunder dome”) is an extinct genus of pachycephalosaurid dinosaur known from the Late Cretaceous (Campanian stage) Two Medicine and Oldman formations of Montana, United States, and Alberta, Canada, respectively. The genus contains a single species, Brontotholus harmoni, known from multiple partial domes.

What we know

  • Named by Woodruff et al., 2025.
  • Body length estimated at about 3.8 m.
  • Fossils found in United States and Canada.