Pachycephalosaurus

***Pachycephalosaurus*** (name meaning "*Thick-Headed Lizard*"), often nicknamed ***Pachy*** for short, is a genus of pachycephalosaurid dinosaur that originated during the Late Cretaceous period of what is now North America. Measuring almost 5 meters long, weighing a ton, and identifiable by its thick domed skull, it is one of the world's most recognizable dinosaurs as well as the largest and namesake of the pachycehalosaurs.

In the Series 2 finale "***Death of a Dynasty II: The Return of the King***", a herd of Pachycephalosaurus (consisting five adults and eight juveniles) were brought to the park from Late Cretaceous Montana, 65 million years ago.

## Facts

### Era & Discovery

*Pachycephalosaurus* lived in western North America during the Late Cretaceous period, from 77 – 65 million years ago. Therefore, it died out with the other dinosaurs at the end of the Cretaceous. It shared its environment with other dinosaurs like the hadrosaurs, ceratopsians, and ankylosaurus as well as the Raptors and *Tyrannosaurus* that saw it as prey.

### Discovery & Range

*Pachycephalosaurus* was first discovered by William Winkley in 1938 in what is now North America.

### Physical Description

The largest known of the dome-headed pachycephalosaurs, *Pachycephalosaurus* grew to stand about 6 – 7 feet (2 – 2.2 m) tall, measured 15 – 17 feet (4.6 – 5.2 m) long, and weighed around roughly 1 ton (2,000 lbs.) Its huge head housed an incredibly thick skull, a tiny brain, and large eyes. Its rounded skull was up to 10 inches thick (25 cm). It also possessed long legs and small forearms. Its head was equipped with a small beak, round eyes, and most notably an extremely thick, domed skull roof.

The 10-inch thick skull domes of *Pachycephalosaurus* was used in intraspecific combat, for example, bashing heads during the mating season, just like the modern ibex do. It is also likely that the animals butted their heads against each other's flanks during the mating season, not unlike giraffes do today. Given the chance, it is also possible they used their heads to defend themselves against predators. Additionally, the head of *Pachycephalosaurus* is strong enough to burst through a concrete wall.

### Behavior & Traits

*Pachycephalosaurus* lived in small herds of around, at maximum, six other individuals in a single herd. Like many herbivores, *Pachycephalosaurus* often separated while feeding, which often gave predators and advantage to attack.

*Pachycephalosaurus* was generally a highly curious creature, known to follow interesting other animals like humans around and to investigate other things of interest. However, when dealing with its own kind, *Pachycephalosaurus* could be highly aggressive, attacking other *Pachycephalosaurus* (or at least what it thought to be them) with a powerful headbutt. *Pachycephalosaurus* also didn't seem to be highly intelligent, as it could mistake its own reflection for another *Pachycephalosaurus*.

Much like the larger ceratopsians, *Pachycephalosaurus* jousted with each other. The young did it for fun, but the adults fought for dominance. With their heads measuring more than 9 inches thick (therefore, making them in comparison to a battering ram) and their spines built to withstand the impact of the hit, it would be very painful to get hit by a *Pachycephalosaurus*.

## Trivia

* Pachycephalosaurus is the last and largest pachycephalosaur brought to the park.
* The sound effects of *Pachycephalosaurus* are that of bull and horse sound effects.