Brontotholus

Brontotholus is a recently named pachycephalosaurid dinosaur discovered in Late Cretaceous strata of North America. Known primarily from thick frontoparietal dome material, this bipedal herbivore possessed a massively reinforced skull composed of dense bone tissue. In life, it likely measured between two and three metres in total body length, moving on slender hind legs while balancing its torso with a stiffened tail. Pachycephalosaurs are widely discussed for the potential function of their cranial domes, with theories ranging from species recognition and sexual display to ritualised pushing or head-to-head combat. Brontotholus inhabited forested floodplain environments where it browsed on soft foliage, shoots, and fruit. Because postcranial bones are exceptionally rare for these animals, scientists rely heavily on variations in cranial ornamentation and dome histologies to understand their evolutionary history.

Named in recent studies, it expands the anatomical diversity of Campanian dome-headed dinosaurs.

Where and when

Brontotholus lived in the Late Cretaceous, from 76 to 74 million years ago (Campanian age). Its remains come from United States, in the Judith River Formation.

The numbers

Length 2.5 m (estimates run from 2 to 3 m). Mass about 60 kg. Hip height about 0.9 m. That is 1.5 human-lengths, or 0.22 of a double-decker bus. These are estimates from fragmentary remains; fields marked estimated by the site are length, mass, first ma, last ma, hip height.

Compare Brontotholus with a bus Place on the timeline