 Chasmosaurines appeared in the early Campanian, and became extinct, along with all other non-avian dinosaurs, during the Cretaceous–Paleogene extinction event.Broadly, the most distinguishing features of chasmosaurinae are prominent brow horns and long frills lacking long spines; centrosaurines generally had short brow horns and relatively shorter frills, and often had long spines projecting from their frills.Chasmosaurines are currently known definitively from rocks in western Canada, the western United States, and northern Mexico.