.24" Fossil Pachycephalosaur Tooth - Judith River Formation

Pachycephalosaurs are a family of bipedal dinosaurs that lived during the Late Cretaceous and had a distinctive, large, bony dome on top of their skull. This dome was sometimes up to 10 inches thick and was thought to cushion their brain from impacts. Some paleontologists believe this thick skull may have been used for head-butting, much like rams while others contend it may have been a sexual display. They were either a herbivore or an omnivore with small leaf shaped teeth which would have been very effective at shredding plants.

There are more than a dozen described genus of Pachycephalosaurs with Pachycephalosaurus from the Hell Creek Formation being the best known.

The Judith River Formation is one of the most prolific sources of Late Cretaceous vertebrate fossils. At least sixteen Orders containing more than forty Genera are known from the formation. These include fish, amphibians, mammals, and insects in addition to the reptiles, avian and non-avian dinosaurs (birds). Among the more interesting specimens is Leonardo, a mummified and fossilized Brachylophosaurus. This is a Hadrosaur, a duck-billed dinosaur with amazing preservation of the soft tissues of the body. The pattern in the skin of the feet is even preserved. In addition to Leonardo, the Judith River Formation contains the remains of the theropod Hesperornis, the only known freshwater Hespernorthid, a penguin like bird.