Centrosaurus -described by Lambe, 1904 (Dodson, 1996). It has all of the diagnostic properties of the Ceratopsia. The skull is more than three feet long, with a single forward thrust nasal horn and small growths over each eye (RTM, 1996). Centrosaurus is a large dinosaur, reaching lengths up to 20ft. (Dodson, 1996). It has a short frill which contains two large fontanelles, the back of which often curve forward like bony hooks drooped over the two large frill openings. Some specimens have been discovered with skin impressions (RTM, 1996). There is evidence that Centrosaurus may have lived in herds for protection from predators. This has been proposed as one theory explaining the remains of more than 50 individuals found in a single site in Dinosaur Provincial Park, Alberta (RTM, 1996). It is thought that a Centrosaurus herd may have tried to cross a river in a flood but the rushing waters were too strong, and hence many drowned. Their carcasses washed onto a sandbar where they remained until the water retreated. When the river flooded again the following year, it buried all unscavenged remains under a layer of sand to be preserved (RTM, 1996).