Pachycephalosaurus Bone Fossil | Hell Creek Formation | South Dakota

Pachycephalosaurus sp.
Cretaceous (68 - 66 million years ago)
Private Ranch, Hell Creek Formation, South Dakota
Assorted sizes available

Receive ONE, random hand selected piece, each one is hand selected for quality and each piece is unique. Comes in a 3.5" x 3.5" floating case. Picture is representative of what you may receive, however actual piece varies.

The name Pachycephalosaurus translates to "thick-headed lizard." This bipedal herbivore was known for its remarkably thick skull roof. It had long hind limbs and relatively small forelimbs. One of its most distinctive features was the large, dome-shaped structure atop its skull, which could be up to 25 cm (10 in) thick, providing protection for its small brain.

The back of the dome featured bony knobs, and short, blunt spikes extended upward from the snout. These spikes were not sharp but likely played a role in display or interactions with other individuals. The dome itself was composed of a special type of bone called fibrolamellar bone, which contained fibroblasts—cells crucial for rapid bone deposition and healing.

Pachycephalosaurus was the largest member of the pachycephalosaurid family. It is estimated to have reached about 4.5 meters (14.8 feet) in length and weighed approximately 450 kilograms. Scientists believe these dinosaurs may have engaged in head-to-head collisions, similar to modern-day bighorn sheep or musk oxen. Males likely rammed into each other, keeping their heads, necks, and bodies aligned horizontally to efficiently absorb and distribute the impact forces.