Pachycephalosaurus

**Pachycephalosaurus wyomingensis** is a genus of pachycephalosaurid dinosaurs. It lived during the late Cretaceous period 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 68-65 mya.

## Description

*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 centimeters (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.

## Lifestyle

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.

## Habitats

It is believe that Pachycephalosaurus lived in woods, forests, feilds, meadows, lowlands, grasslands and plains of Montana, North Dakota, South Dakota, Wyoming and Alberta during the Late Cretaceous and little bit in the Early Paleogene. The dinosaurs it shared these locations with can be found in many of the same locations that Pachycephalosaurus inhabited. The flodplains that Pachycephalosaurus lived in had trees, grass, shrubs, ferns, woodlands, ponds, streams, rivers, brooks, creeks and valleys.

### Lance Formation

Was a plain filled with streams forest and woods the formation was named after Lance Creek and located in Wyoming. The Lance Formation was one of the many places that Pachycephalosaurus called home it had plains with trees, meadows, feilds, steams, creeks, brooks, ponds, ferns, shrubs and wooded areas but it was mostly believed to be a wetland floodplain. Pachycephalosaurus not only lived alongside dinosaurs in the Lace Formation but it shared the area with birds, reptiles like lizards, crocodiles, alligators, snakes, turtles, alongside amphibians like, frogs, salamanders and toads, also invertebrates like, arachnids, insects, arthropods, crustaceans, fish and small mammals. Pachycephalosaurus has also been found near Lance Creek.

### Scollard Formation

Was a plain located near Scollard Canyon the formation is named after the canyon in Alberta, Canada. Scollard Formation was one of the many places that Pachycephalosaurus made it's home like other habitats that the dinosaur lived in this location was believed to be a floodplain at one point with forests, meadows, fields, brooks, ponds, creeks, ferns, grass, trees, shrubs and woods located in the plains. Pachycephalosaurus has also been found alongside next to the Scollard Canyon. Animals like, birds, fish, amphibians like, frogs, toads, salamanders, birds, reptiles like, snakes, lizards, turtles, alligators, crocodiles, invertebrates like, insects, arachnids, crustaceans, arthropods, and small mammals lived in plains of Scollard at the sametime with Pachycephalosaurus and other dinosaurs.