Pachycephalosaurus Dinosaur Claw from the Hell Creek Formation

Description: The Pachycephalosauria, meaning thick headed lizards, is a family of dinoaurs from Order Ornithischia that includes such well known genera include Pachycephalosaurus, Stegoceras, Stygimoloch, and Dracorex. Most lived during the Late Cretaceous Period, in what is now North America and Asia. The probably traveled in herds. They were all bipedal, herbivorous/omnivorous animals noted for having thick skulls. Some has a domed skull roof that was several inches thick sometimes surrounded by nodes.

The function of the thickened skull roof has been heavily debated. It has been frequently asserted that individuals may have rammed each other head-on, as do modern-day mountain goats and musk oxen. It is also suggested that pachycephalosaurs could make their head, neck, and body horizontally straight, in order to transmit stress during ramming. However, in no known dinosaur can the head, neck, and body be oriented in such a position. Instead, the cervical and anterior dorsal vertebrae of pachycephalosaurs show that the neck was carried in an "S"- or "U"-shaped curve.