パキセパロサウルス Pachycephalosaurus オーストラリア恐竜大陸
Ornithischia / Genaria / Cerapoda / Marginocephalia
/ Pachycephalosauria / Family: achycephalosauridae
/ First Described: 1943 / Found: North America: USA
/ Length: 8m / Weight: 1t
/ Food: Plants / Young: Eggs
/ Lived: Late Cretaceous 76－68 million years ago
Pachycephalosaurus is known, only poorly, from Wyoming, South Dakota and Montana in the western United States. It was one of the largest of the dome? or flat?headed dinosaurs, with the thick, bony mass at the top of its head up to 20 cm (8 in) thick. As with other pachycephalosaurs, this strengthening and thickening of the skull protected it during fights for territory, dominance of the herd or mating partners. The bigger the male, the bigger the domed skull and the more likely that he would be the victor in battle.
Only one good fossil Pachycephalosaurus skull has been found, as well as several skull roofs. The reconstruction of the rest of the animal is based on comparing it with related dinosaurs and on
Informed guesswork. A detailed comparison is now possible because a reasonably complete skeleton of the closely related Stygimoloch was found in 1995. Each animal had a bony ornament over the snout and rear of the head, but in Stygimoloch, the rear bony swellings had developed into long horns. Both animals ran on two legs. They probably had relatively short arms and a long, stiffened tail.