Pachycephalosaurus/Tylosteus is a genus of pachycephalosaurid dinosaurs. It lived during the late cretaceous in what is now North America. Remains have been excavated in Montana. It was an herbivorous creature which is only known from a single skull and a few extremely thick skull roofs. Pachycephalosaurus lived 68-67 mya.
Pachycephalosaurus was probably bipedal and was the largest known of the bone-headed dinosaurs, with some others being Stygimoloch, Dracorex, and Stegoceras. It is famous for having a large, bony dome atop its skull, up to 25 cm (10 inches) thick, which safely cushioned its brain. The dome's rear aspect was edged with bony knobs and short bony spikes were projected upwards from the snout. These features suggest that, despite their bipedal stance, they were likely to have been relatives of the ceratopsians.
Using data from other pachycephalosauridae, it has been estimated that Pachycephalosaurus was approximately the length of a large car, maybe around 4.6m long (15 feet) and had a fairly short, thick neck, short fore limbs, a bulky body, long hind legs and a heavy tail, which was likely to have been held rigid by ossified tendons. Large eye-sockets that faced forward suggest that the animal had good vision and was capable of binocular vision.
Scientists once suspected that Pachycephalosaurus and its dome-headed relatives were the bipedal equivalents of the big-horned sheep of today. It was thought that, in the mating season, big males would run at one another, clashing heads to decide which would dominate and mate with a herd of females. It was also thought that they might have used their domed heads for defence against predators. However, it is now believed that the Pachycephalosaurs would not have used their domes in this way so much. The adult head bones could not adequately have withstood pressure and impact and the skulls lacked proper shock absorption like Big Horned Sheep, and it's more likely that they head-butted their sides, to try to knock them off balance. Also, there is no evidence of scars or other damage on fossilized Pachycephalosaurus skulls. On the other hand, it's unlikely that pachycephalosaurs developed those thick skulls for display alone. It's a rather opinionated discussion.
Scientists do not yet know what these dinosaurs ate. Having very small, ridged teeth they could not have chewed tough, fibrous plants as effectively as other dinosaurs of the same period. It is assumed that pachycephalosaurs lived on a mixed diet of leaves, seeds, fruit and insects. The sharp, serrated teeth would have been very effective for shredding plants.
- The Transforme
characters of Hard head and Dinotron turned into Pachycephalosaurus.
- A Zord in Power Rangers: Dino Thunder was based on Pachycephalosaurus, and another in Power Rangers: Dino Charge.
- Pachycephalosaurus made a brief cameo in Ice Age Dawn of the Dinosaurs. They are rideable in one level of the video game adaption.
- It is a huntable species in Carnivores.
- Pachycephalosaurus appears in Anime film Age of the Great Dinosaurs with one being the victim of the one-eyed Tyrannosaurus rex.
- A Pachycephalosaurus is hunted by two Troodon in Dinosaur Revolution. It is the model of the scrapped Prenocephale.
- Pachycephalosaurus appears in Bizarre Dinosaurs.
- It also made an appearance in Dinosaurs Decoded, where Jack Horner talks about howStygimoloch and Dracorex are actually young Pachycephalosaurus, however, not many people agree with this, and the idea has mostly been rid of.
- It also appeared in Dinosaur Train in season 2.
- In Pokemon series, Cranidos and its evolved form Rampardos are based on Pachycephalosaurus.galleryEdit