skull of ceratopsia (chasmosaurus belli) greek: horned faces ) is a group of herbivorous, beaked dinosaurs which thrived in what are now north america and asia, during the cretaceous period. members developed elaborate facial horns and a neck frill. while the frill might have served to protect the vulnerable neck from predators, it may also have been used for display, thermoregulation, the attachment of large neck and chewing muscles or some combination of the above. ceratopsians ranged in size