Pachycephalosaurs
| Pachycephalosaurs Temporal range: Late Cretaceous, 90–66 Ma |
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| Cast of a Pachycephalosaurus wyomingensis skull, Oxford University Museum of Natural History | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Order: | †Ornithischia |
| Suborder: |
†Pachycephalosauria Maryańska & Osmólska, 1974 |
| Family: |
†Pachycephalosauridae Sternberg, 1945 (conserved name) |
| Type species | |
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†Pachycephalosaurus wyomingensis Gilmore, 1931 (conserved name) |
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| Genera | |
| Synonyms | |
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Homalocephalidae Dong, 1978 |
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Homalocephalidae Dong, 1978
Pachycephalosauria (/ˌpækiˌsɛfələˈsɔːriə, ˌkɛ-/; from Greek παχυκεφαλόσαυρος for 'thick headed lizards') is a clade of ornithischian dinosaurs. Along with Ceratopsia, it makes up the clade Marginocephalia. Genera include Pachycephalosaurus, Stegoceras, and Prenocephale. With the exception of two species, most pachycephalosaurs lived during the Late Cretaceous Period, dating between about 85.8 and 65.5 million years ago. They are exclusive to the Northern Hemisphere, with the majority being found in what is now North America and Asia. They were all bipedal, herbivorous/omnivorous animals with thick skulls. Skulls can be domed, flat, or wedge-shaped depending on the species, and are all heavily ossified. The domes were often surrounded by nodes and/or spikes. Partial skeletons have been found of several pachycephalosaur species, but to date no complete skeletons have been discovered. Often isolated skull fragments are the only bones that are found.
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Wikipedia