Isla SornaEdit


Illustration by FeatherTail of JPLegacy

Length: 13 metres
Height: 5 feet
Weight: 1,000 pounds


Adult and juvenile (both sexes): Blue and brown mottling.

Diet: Herbivore. Pachycephalosaurus 'it does not have to bother with chewing. Grass, leaves, fruits and pine cones make up a large part of its diet. Pachycephalosaurus is another feting-vat herbivore, and as a result is prone to occasional bouts of flatulence.

Preferred Habitat: Upland forests of the Mountain Ranges or Southern Highlands, but will make do with scattered brush elsewhere.

Social Structure: Small groups to medium-sized herds consisting of several females, their young, and a few subordinate males led by a single dominant stag who guards his herd fiercely. Some males may be solitairy, usually as a result of being evicted from their herd by a stronger male. Sometimes, Pachycephalosaurus herds can also quite happily mingle with other large herbivores while grazing.

Pachycephalosaurus is a tough animal, quite large and bulky, and easily recognized for its tall, domed head. Well known for its aggressive head-ramming, the dome of Pachycephalosaurus' skull is 30 cm thick. Surrounding the dome and decorating the snout are bony knobs and short bony spikes. These are more pronounced in males than in females. Infants of both sexes also have blunt knobs (males develop spikes as they age). Hatchlings lack the familiar dome of the adults; instead their skulls are flat.. Their skulls rise and thicken as they grow, eventually forming into the dome.

Pachycephalosaurus is known for its aggressive, territorial nature, and both sexes will use their domed skulls as weapons. When faced with danger, Pachycephalosaurus may try to defend themselves by facing the predator with lowered heads, snorting and stamping their feet. Although not so effective against large carnivores, such as Tyrannosaurus, charging at smaller predators such as Velociraptor and ramming into their sides can be fatal; having the potential to break bones and crush organs.

Males are much more aggressive than the more docile females, and usually one dominant stag leads over a harem of females, their young, and a few subordinate "defender" males. During the breeding season, the aggression of the males explode and they will compete over each other for females. The spikes on the base of their domes will grow dramatically, and they will use these spikes to impress females and warn off less experienced males. Equally matched males will face one another, posturing and roaring, and unless one backs down they may fight, using their domed skulls to batter each other into submission. The winner will then gain control of the females while the loser is usually evicted from the herd.

The Pachycephalosaurus' vocalizations include bleats, growls, bellows and snorts, and some kind of shriek, similar to a pig's squeal, produced when the animal is scared.

For more information, see: Pachycephalosaurus wyomingensis (S/F)