Ceratopsidae (sometimes spelled Ceratopidae) is a speciose group of marginocephalian dinosaurs including Triceratops and Styracosaurus. All known species were quadrupedal herbivores from the Upper Cretaceous of Western North America and are characterized by beaks, rows of shearing teeth in the back of the jaw, and elaborate horns and frills. The group is divided into two subfamilies. The Ceratopsinae or Chasmosaurinae are generally characterized by long, triangular frills and well-developed brow horns. The Centrosaurinae had well-developed nasal horns or nasal bosses, shorter and more rectangular frills, and elaborate spines on the back of the frill.