Dinosauria › Ornithischia › Cerapoda › Marginocephalia Pachycephalosauridae Dome-headed bipedal herbivores. Sphaerotholus goodwini 145–66 Mya · United States Platytholus clemensi 100–66 Mya · United States Sinocephale 100–66 Mya · China Tylocephale 100–66 Mya · Asia Amtocephale 96–89.6 Mya · Mongolia Acrotholus 84–83.5 Mya · North America Colepiocephale lambei 80.45–78 Mya · Canada Hanssuesia 77.5–75 Mya · United States Foraminacephale brevis 77–73 Mya · Canada Stegoceras validum 77–74 Mya · North America Brontotholus harmoni 75.5–75.3 Mya · United States Alaskacephale 70–69 Mya · North America Pachycephalosaurus wyomingensis 70–66 Mya · North America