Pachycephalosaurus

* Adult P. wyomingensis (Current)
* Adult P. spinifer (Future)
* Sub-adult P. spinifer
* Juvenile P. spinifer
* Hatchling P. spinifer

*"Pachycephalosaurus (Thick-Headed Saurian) are famous for their unique domed skulls. These are the staple small herbivore of Hell Creek and the most common dinosaur on the floodplain. Without the grinding teeth of larger animals, Pachycephalosaurus are limited to softer plants that they can easily shred. The skull of Pachycephalosaurus changes at lot with age, with the dome developing only later in life. This lead to some confusion among palaeontologists, with younger specimens being initially classified as their own species."*

― *Saurian* encylopedia

***Pachycephalosaurus*** is a genus of pachycephalosaurid dinosaurs. The type species, *P. wyomingensis*, is often regarded as the only known valid species, though *P. spinifer* has been proposed as a second species of *Pachycephalosaurus*, after being previously assigned to the genus *Stygimoloch*. It will be the last playable dinosaur to be added in the base game of *Saurian*, preceeded, however, by the bonus playables.

## Information

*Pachycephalosaurus* lived during the Late Cretaceous Period (Maastrichtian stage) of what is now North America. Remains have been excavated in Montana, South Dakota, and Wyoming. It was a herbivorous creature which is primarily known from a single skull and a few extremely thick skull roofs, though more complete fossils have been found in recent years. *Pachycephalosaurus* was one of the last non-avian dinosaurs before the Cretaceous–Paleogene extinction event.

Scientists do not yet know what these dinosaurs specifically ate. Having very small, ridged teeth they could not have chewed very 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, and fruits. The sharp, serrated teeth would have been very effective for shredding plants.

Paleontologists have heavily debated for several decades the adaptive significance of pachycephalosaurid domes. A study from Horner suggested that the skull roof could probably not have adequately sustained impact associated with such ramming and would have been risky. However, more recent studies showed that pachys did headbutt, due to the discovery of lesions in the skull which could only be caused by head trauma. And although pachycephalosaurs with flatter, smaller domes — which paleontologists believe were females and juveniles — were included in the study sample, none of them appeared to have suffered any trauma. This suggests not only that head-butting was limited to adult males but also that — if modern animal behavior is any indication — it was likely used by them to fight over females which is most likely. Some scientists had previously theorized that the dinosaurs’ peculiar domes were sex characteristics intended to attract mates, like an elk’s antlers or a peacock’s tail feathers. The new study intimates that the bony crests were meant not only to draw the eye but also to fight for the right to mate. This is not unlikley as it would serve as a very prominent piece on it's head.

While *Pachycephalosaurus* is mostly known from skulls, based on other pachycephalosaurids, it has been estimated that *Pachycephalosaurus* was around 4.5 meters (15 ft) long and weighed 450 kilograms (990 lb). Based on other pachycephalosaurids, it probably had a fairly short, thick neck, short fore limbs, a bulky body, long hind legs and a heavy tail, which was likely held rigid by ossified tendons.

## Physical appearance

As an adult, *Pachycephalosaurus* is fully scaled with a spiny tail and skin on the legs in the form of uropatagium. Its' color is gray with brown stripes to match its' habitat and a red face and throat for display and white dome. Males of this species have bright red heads.

## Behavior and Biology

*Pachycephalosaurus* is a vulnerable prey animal in the Hell Creek, preferring to live in densely forested areas to avoid predators such as *Tyrannosaurus*, yet is hardy and belligerent and will attack *Dakotaraptor* or young *Tyrannosaurus* when provoked. *Pachycephalosaurus* uses its bone-breaking domed head as a multifunctional tool, being used to defend against as previously mentioned, territorial disputes, and to deflect forest foliage while running. These dome-headed dinosaurs mate for life and both parents raise their young for several months. Males are fiercely territorial and will engage in head and flank butting contests. *Pachycephalosaurus* are herbivorous animals, feeding on low-growing vegetation as well as fungi and occasionally insects.

## In *Saurian*

*Pachycephalosaurus* is planned to be the last playable animal introduced in the base game. *Pachycephalosaurus* have a somewhat aggressive temperament and some can even be observed hurting members of the same species and more often they can be seen taking down crocodylomorphs. *Pachycephalosaurus* frequently spawn in pairs, as they apparently mate for life. Currently, *Pachycephalosaurus* do not display sexual dimorphism or ontogeny.

### *Dakotaraptor* gameplay

Currently, *Pachycephalosaurus* only serves as a potential prey item for *Dakotaraptor* gameplay. Only adults have considerable chances to hunt one down, but they are dangerous to kill without using RPR (Raptor Prey Restraint), as their head butting causes severe damage. Usually, players will run out of stamina when attempting to take down one, after a failed RPR, and they may not escape when the *Pachycephalosaurus* comes to inflict a last fatal blow. *Pachycephalosaurus* are usually aggressive and will charge towards the player even when they're not attacking, and this may occur more frequently if the player uses the threat signal.

### *Triceratops* gameplay

If you're a *Triceratops*, they tend to be quite peaceful towards you, due to their shared herbivorous nature. However they may run away if you get too close when you're an adult, since you can easily kill it. They may be dangerous for hatchling *Triceratops*, if accidental trampling occurs. Starting from the juvenile stage, dying from *Pachycephalosaurus* trampling is unlikely, but accidental trampling may cause conflict between the two herbivorous species. As you reach subadult stage, they are much more safe to take down.

## Gallery

*Pachycephalosaurus* attacking animationsFor a more complete gallery, visit Pachycephalosaurus/Gallery

## Behind the scenes

*Pachycephalosaurus* has gone through several design changes over the course of the game.

Chris Masna created early concepts on the *Pachycephalosaurus* depicting them with vibrant colors as opposed to later designs of *Pachycephalosaurus*. RJ Palmer created further designs of the *Pachycephalosaurus*. The first by Palmer was released on November 18, 2014, and featured prominent spikes on the skull, a sail running down most of the back, and spikes at the tip of the tail. Palmer then created another design that lacked the traits of his previous concept and had a larger tail. This design was later chosen for the in-game model until it was scrapped on September 15, 2016.

The former genera *Stygimoloch* and *Dracorex* are traditionally transformed into the subadult and juvenile form of the *Pachycephalosaurus*, which is what is believed to be accurate. It is still debated, however, as they may be different genera.

*Pachycephalosaurus* was supposed to be the second playable dinosaur to be added in the game, but that place was taken by *Triceratops*. This was because the ontogenic seamless growth was much easier to make on *Triceratops* than *Pachycephalosaurus* mostly because the former has fewer horns, and because those horns don't shift in their configuration in the way that *Pachycephalosaurus* does. It has since been delayed to be the fourth released playable dinosaur, as *Tyrannosaurus* is slated to be released before *Pachycephalosaurus*, presumably because the ontogeny would be easier to implement in *Tyrannosaurus* as well.

## Notes and references

1. ↑ 1.0 1.1 1.2 Playable Animals. *Saurian* Website. Retrieved October 10, 2016
2. ↑ (November 18, 2014) *Saurian* Facebook.
3. ↑ Parker, Tom. (September 15, 2016) Saurian Devlog #3. *Saurian* Website.