chasmosaurines

Chasmosaurines are a clade within Ceratopsidae, one of the two major subfamilies of horned dinosaurs. They are known for elaborate skull ornamentation and long cranial horns. They lived during the Late Cretaceous, from the late Campanian to the Maastrichtian, predominantly in western North America, where they coexisted with centrosaurines.

The group is diagnosed by skull features such as elongated frills and prominent brow horns, with a wide variety of frill shapes and ornamentation among genera. In contrast to centrosaurines, which tend to have different horn and frill configurations, chasmosaurines often exhibit longer brow horns and more elaborate frill margins. They were herbivorous, equipped with beaked mouths and dental batteries suited to processing tough vegetation, and many lineages likely formed social groups or herds.

Notable genera within Chasmosaurinae include Chasmosaurus, Pentaceratops, Kosmoceratops, Utahceratops, Torosaurus, and Triceratops. Kosmoceratops is renowned for its numerous horn-like projections, while Pentaceratops is characterized by a prominent frill and multiple horns. Triceratops and Torosaurus are among the best-known examples from the later Cretaceous of North America, illustrating the diversity and size range within the subfamily.

The chasmosaurines are important for understanding ceratopsid evolution and Late Cretaceous paleoecology. Their diverse horn and frill morphologies inform discussions of display, species recognition, and ecological adaptation within ceratopsids.