Stenotholus Facts
| Diet | Herbivore |
| Height | 1m |
| Length | 2m |
| Weight | 50 kg |
| Environment | Land |
| Era | Cretaceous |
| Period | Late Cretaceous |
| Type | Pachycephalosaur |
| Location | North America |

| Diet | Herbivore |
| Height | 1m |
| Length | 2m |
| Weight | 50 kg |
| Environment | Land |
| Era | Cretaceous |
| Period | Late Cretaceous |
| Type | Pachycephalosaur |
| Location | North America |
Stenotholus was a small pachycephalosaur that lived during the Late Cretaceous period, between 83.6 and 72.2 million years ago, in what is now North America. This bipedal herbivore is known primarily from fragmentary skull remains discovered in the Judith River Formation of Montana, making it one of the less well-understood members of the dome-headed dinosaur family.
Like other pachycephalosaurs, Stenotholus possessed a thickened skull roof, though the extent and exact shape of this dome remains uncertain due to the limited fossil material. The creature likely measured around 2 metres in length and stood approximately 1 metre tall at the hip, making it considerably smaller than its famous relative Pachycephalosaurus. Its estimated weight of around 50 kilograms suggests it was a relatively lightweight dinosaur.
As a herbivore, Stenotholus would have fed on low-growing plants, ferns, and possibly fruits using its small, leaf-shaped teeth. Its bipedal stance and long legs suggest it was capable of quick movement, which would have been essential for escaping predators in the dangerous Cretaceous landscapes of ancient Montana.
The scientific validity of Stenotholus remains debated amongst palaeontologists, as the fragmentary nature of the fossil evidence makes it difficult to determine whether it represents a truly distinct genus or simply juvenile remains of another pachycephalosaur species.
Stenotholus is characterised by its thickened skull roof, though the exact dome structure is uncertain due to fragmentary remains. It was notably smaller than most other known pachycephalosaurs, with a more gracile build suited to swift movement.
Stenotholus likely lived in small herds, using its speed and agility to evade the large predators of Late Cretaceous North America. The thickened skull may have been used for display purposes or possibly head-butting contests with rivals, though this remains speculative given the limited fossil evidence.
Stenotholus was first described by Peter Galton and Hans-Dieter Sues in 1983. The original fossils were discovered at Judith River Formation, Montana, USA.