Pachyrhinosaurus (Pack-ee-rye-no-sore-us), Thick Nosed Lizard, lived in the late Campanian through early Maastrichtian of the Late Cretaceous of North America. It looked like most centrosaurs it had a short frill the adults seem to have a thick boney pad in place of the typical centrosaurine nose horn.
Genera and Species
Classification: Marginocephalia, Ceratopsia, Ceratopsidae, Centrosaurinae.
Species: P. Canadensis, P. lakustai
Pachyrhinosaurus had 1 to 3 straight horns in the middle of its frill that varied by species and even among individuals. Adults had a short neck frill and a thick pad of bone on the top of its nose between the eyes. Juveniles did have a low nasal horn. It has been suggested that the massive nose pad supported a keratinous horn but no fossil evidence supports this reconstruction. The body is in the centrosaur template but the tail shorter.
Length 5.5 -7 m (18 - 22 ft).
Weight 3 tons.
It was an herbivore. A single species bone bed with more than 2500 specimens indicates that at least seasonally they must have gathered in large herds. This is taken as evidence of a herd being caught try to cross a river in flood. These are large animals and they may have needed to change pastures periodically.
History of Discovery
Discovered by Sternberg, in 1950 and known from 12 partial skulls, disarticulated skull and skeletal material.
Found in North America (Alaska through Montana) in well watered flood plains with marshes and swamps subject to cool to cold winters.
Paul, G. (2010). The Princeton Field Guide to Dinosaurs (pp. 6090). Princeton, New Jersey: University Press Princeton.
Worth, G. (1999). The Dinosaur Encyclopaedia (pp. 1676). Scarborough, Western Australia: HyperWorks Reference Software.