Describer

Leidy, 1872

Time

Cretaceous Late

Classification

Ornithischia Genasauria Cerapoda Marginocephalia Pachycephalosauria Pachycephalosauridae Nomen Oblitum

Diet

Herbivore

Fossilsite

Black Foot Country, outcrop area of the Lance and Hell Creek Formations, Montana or Wyoming, US

Fall Under

Pachycephalosaurus

Info

Genus - Nomen Oblitium

Pachycephalosaurus (Brown& Schlaikjer, 1943) = Tylosteus (Leidy, 1872)

Pachycephalosaurus > Pachycephalosaurus wyomingensis (Gilmore, 1931) >> Troodon wyomingensis (Gilmore, 1931) >>> Tylosteus ornatus (Leidy, 1872), Pachycephalosaurus grangeri (Brown & Schlaikjer, 1943) Pachycephalosaurus reinheimeri (Brown & Schlaikjer, 1943)

Pachycephalosaurus (Brown& Schlaikjer, 1943) > Pachycephalosaurus wyomingensis (Gilmore, 1931) > Dracorex hogwartsia [Juvenile] (Bakker, Sullivan, Porter, Larson & Saulsbury, 2006) > Stygimoloch spinifer [subadult] Galton & Sues, 1983 >> Stenotholus kohleri (Giffin, Gabriel & Johnson, 1987)

A fragmentary left squamosal (ANSP 8568) named Tylosteus ornatus is the first official description of Pachycephalosaurus.

Donald Baird (1979) identified the specimen as a skull fragment from Pachycephalosaurus. [name suppressed for purposes of priority but not homonymy by ICZN Opinion #1371]