Finally, an enamel pin honoring your favorite dinosaur you never met.
- Species: P. Wyomingensis
- Temporal range: Late Cretaceous, 70–66 Ma
- Location: Montana, South Dakota, and Wyoming.
Pachycephalosaurus (/ˌpætʃɪˌkɛfələˈsɑːrəs/; meaning "thick-headed lizard," from Greek pachys-/παχυς- "thick", kephale/κεφαλη "head" and sauros/σαυρος "lizard") is a genus of pachycephalosaurid dinosaurs. The type species, P. wyomingensis, is the only known species. It lived during the Late Cretaceous Period (Maastrichtian stage) of what is now North America. Remains have been excavated in Montana, South Dakota, and Wyoming. It was a herbivorous creature which is primarily known from a single skull and a few extremely thick skull roofs, though more complete fossils have been found in recent years.