Concise hierarchy

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

Phylogeny

Branch-based clade

Ref: P.C. Sereno, 1998: table 4 (p. 62). [implicit]

Defined by included taxon (and all taxa more closely related to it than to the excluded taxon)

†Stegoceras validus

Ref: P.C. Sereno, 1998: table 4 (p. 62).

Defined by excluded taxon

†Pachycephalosaurus (Genus) Brown & Schlaikjer, 1943

Ref: P.C. Sereno, 1998: table 4 (p. 62).

Included, by definition, in node-based clade

†Pachycephalosauridae (Clade) Sternberg 1945

Ref: P.C. Sereno, 1998: table 4 (p. 62).

Excluded, by definition, from branch-based clade

†Pachycephalosaurinae (Clade) Sereno 1998

Ref: P.C. Sereno, 1998: table 4 (p. 62).

Subsequent positions

†Tholocephalidae (Family) Sereno, 1986, nom. inval.

Ref: P. Sereno, 1986: 252.

Original entries

†Stegoceras lambei C.M. Sternberg, 1945

Current position

†Pachycephalosauridae (Family) Sternberg, 1945

Ref: R.M. Sullivan, 2006: 357. [inferred name]

Alternative positions

†Pachycephalosauridae (Clade) Sternberg 1945	Ref: P.C. Sereno, 1998: table 4 (p. 62).
†Tholocephalidae (Family) Sereno, 1986, nom. inval.	Ref: P. Sereno, 1986: 252. [new position]

Historical positions

†Pachycephalosauridae (Family) Sternberg, 1945	Ref: R.M. Sullivan, 2006: 353. [invalid/synonym]
†Pachycephalosauridae (Clade) Sternberg 1945	Ref: P.C. Sereno, 1998: table 4 (p. 62), fig. 6.
†Tholocephalidae (Family) Sereno, 1986, nom. inval.	Ref: P. Sereno, 1986: 252. [new position]

Number of Subtaxa

2025	Available in Systema Naturae 2000	†2s
1989-present	Systema Naturae 2000	[; †1[2]s]
2006	R.M. Sullivan: 361	[; †1[2]s]