Concise hierarchy

(Kingdom) Animalia - (Phylum) Chordata - (Class) Reptilia - (Order) Ornithischia

Subsequent positions

†Ceratopsia (Infraorder) Marsh, 1890		Ref: Sues & Galton, 1982. [assumed]
†Pachycephalosauridae (Family) Sternberg, 1945		Ref: T. Maryañska & H. Osmólska, 1974 [assumed]

Current position

†Ornithischia (Order) Seeley, 1887

Ref: R.M. Sullivan, 2006: 349. [implicit]

Alternative positions

†Ceratopsia (Infraorder) Marsh, 1890	Ref: R.M. Sullivan, 2006: 349 (Galton & Sues, 1982). [by reference]
†Ornithischia (Clade) Seeley 1887 [Padian & May 1993]	Ref: R.M. Sullivan, 2006: 349.
†Pachycephalosauria (Clade) Maryañska & Osmólska 1974	Ref: P.C. Sereno, 1998: 68 (fig. 6).
†Pachycephalosauridae (Family) Sternberg, 1945	Ref: R.M. Sullivan, 2006: 360. [excluded]
†Protoceratopsidae (Family) Granger & Gregory, 1923	Ref: G. Olshevsky, 1991: 161.
†Psittacosauridae (Family) Osborn, 1923	Ref: D. Lambert & the Diagram Group, 1991(1997)

Historical positions

†Pachycephalosauridae (Family) Sternberg, 1945	Ref: R.M. Sullivan, 2006: 348. [excluded] [implicit]
†Pachycephalosauria (Clade) Maryañska & Osmólska 1974	Ref: P.C. Sereno, 1998: 68 (fig. 6).
†Protoceratopsidae (Family) Granger & Gregory, 1923	Ref: G. Olshevsky, 1991: 161.
†Ceratopsia (Suborder) Marsh, 1890	Ref: R.L. Carroll, 1988: App. (p. 622).

Number of Subtaxa

2026	Available in Systema Naturae 2000	†1s
1989-present	Systema Naturae 2000	[; †1s]
2006	R.M. Sullivan: 348	[; †1s]