The "thickhead reptile" was described by Gilmore in 1931.
Pachycephalosaurus lived during the Late Cretaceous Period about 67 to 65.5 million years ago. It was about 4 meters (13 ft) in length, 1 and half meters (5 ft) in height and 800 pounds (365 kilos) in weight.
It can be found on Isla Sorna herding with Gallimimus and Parasaurolophus.
