Pachycephalosaurus Temporal range: Late Cretaceous, 70–66 Ma |
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Cast of the "Sandy" specimen | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Clade: | Dinosauria |
Order: | †Ornithischia |
Family: | †Pachycephalosauridae |
Tribe: | †Pachycephalosaurini |
Genus: |
†Pachycephalosaurus Brown & Schlaikjer, 1943 (conserved name) |
Type species | |
†Pachycephalosaurus wyomingensis Gilmore, 1931 (conserved name) |
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Species | |
†Pachycephalosaurus wyomingensis |
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Synonyms | |
Tylosteus ornatus Leidy, 1872 |
†Pachycephalosaurus wyomingensis
(Gilmore, 1931) (conserved name)
Tylosteus ornatus Leidy, 1872
(rejected name)
Troodon wyomingensis Gilmore, 1931
Stygimoloch spinifer? Galton & Sues, 1983
Dracorex hogwartsia? Bakker et al., 2006
Pachycephalosaurus (/ˌpækᵻˌsɛfələˈsɔːrəs/; 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 an 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. Pachycephalosaurus was one of the last non-avian dinosaurs before the Cretaceous–Paleogene extinction event. Another dinosaur, Tylosteus of western North America, has been synonymized with Pachycephalosaurus.