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Clade
Subclade

Taxon
Taxon
Pachycephalosaurinae
Nominal Author
Sternberg 1945
2nd Nominal Author
Sereno 1998
Taxon Status ACTIVE
Comments

Sereno (1998) defined Pachycephalosaurinae as a stem-based clade to include pachycephalosaurs more advanced than Stegoceras validum. Sullivan (2003:189) used the taxon in the same way (incorrectly listing Sereno, 1998 as its author). Without explanation, however, he revised the definition as node-based with additional internal specifiers

The name, as defined by Sereno (1998), was party to a node-stem triplet (with Pachycephalosauridae and Stegoceras). It is not clear what is to be gained by breaking up that association. The active definition is a first-order revision of the stem-based definition in Sereno (1998) that uses species as specifiers.

Potential Synonomy

Active Phylogenetic Definition
Active Definition
The most inclusive clade containing Pachycephalosaurus wyomingensis (Gilmore 1931) but not Stegoceras validum Lambe 1918.
Shorthand
> Pachycephalosaurus wyomingensis but not Stegoceras validum.
Definitional Author
Sereno 2005
Definition Status checked
Definition Type STEM
Node-Stem Triplet NO
Other Triplet Taxa
Specifiers
Specifier(s) A
Pachycephalosaurus wyomingensis
Specifier(s) B
Specifier(s) C
Stegoceras validum
Qualifiers
+Taxon
-Taxon
Datum
Taxonomic Content
Publication Year Unknown
Unknown
Unknown
1998

Inactive Taxon Status
Rejection Criteria
Critique
 

Definitional History #1
Earliest Record
All pachycephalosaurids closer to Pachycephalosaurus than to Stegoceras.
Latest Record
Sereno 1998:62
Range (My)
Range (My)
Pachycephalosaurus,Stegoceras
Range (My)

Definitional History #2
Earliest Record
Colepiocephale, Prenocephale, Tylocephale, Hanssuesia, Pachycephalosaurini (= Pachycephalosaurus + Stygimoloch), their most recent common ancestor and all descendants.
Latest Record
Sullivan 2003:189
Range (My)
Range (My)
Colepiocephale, Prenocephale, Tylocephale, Hanssuesia, Pachycephalosaurini
Range (My)

Definitional History #3
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Definitional History #9
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Definitional History #10
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