skeleton of pachyrhinosaurus dinosaur. pachyrhinosaurus (meaning thick-nosed reptile ) is a genus of ceratopsid dinosaur from the late cretaceous period of north america. instead of horns, the skull bears massive, flattened bosses, the largest being over the nose. these were probably used in butting and shoving matches, as in musk oxen. a single pair of horns grew from the frill and extended upwards. it appears that that both the shape and size of the frill was highly individualized. pachyrhinos