What can you tell me about Pachyrhinosaurus?
Pachyrhinosaurus was a large (25-foot-long) ceratopsian dinosaur from North America. At least three distinct species are known, the fossils of which have been found in Alberta and Alaska - although not in between. It may have seasonally migrated between the two locations, although that’s just my own theory.
(A pair of Pachyrhinosaurus, by James Havens.)
Unlike most ceratopsians, Pachyrhinosaurus had no horns over its eyes or nose. Instead, it had large, bony “bosses” in those locations. The exact shapes of these structures, as well as the arrangements of ornamental spikes, horns, and nodules on the frill, differed from species to species. These blunt structures were likely less useful for defense against predators than the horns of, say, Triceratops; they may have been used for “head-butting”, in order to compete with other members of their species. They might even have been anchor points for keratinous structures, like the horns of a rhinoceros! Again, however, that’s just my own theory.
(Pachyrhinosaurus using their nasal bosses to headbutt one another. By Karen Carr.)
Pachyrhinosaurus lends its name to the tribe Pachyrhinosaurini. The members of this tribe, the pachyrhinosaurines, are united by their reduced horns in comparison with other large ceratopsian species. Einiosaurus’ nose horn was a forward-pointing “can opener”, while Wendiceratops, discovered only in 2015, had a broad nose horn with a blunted tip. It’s unknown why the members of this family had such odd-looking horns and bosses; since the pachyrhinosaurines are members of Centrosaurinae, a ceratopsian clade known to have used its horns more for display than combat, its possible that they were the results of a trend away from defense and towards display.
(Wendiceratops, by Danielle Dufault.)
