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Andreas Johansson wrote:
Presumably to prevent just that, Sereno's Taxon Search gives this
definition of Tetanurae:
The most inclusive clade containing Passer domesticus (Linnaeus 1758) but
not Ceratosaurus nasicornis Marsh 1884, Carnotaurus sastrei
Yes, I think you're right. Previous definitions of Tetanurae (e.g., Padian
et al., 1999; Wilson et al. 2003; Holtz et al. 2004) used only
_Ceratosaurus_ as an external specifier. Adding _Carnotaurus_ as an exernal
specifier caters for the possibility that ceratosaurids and abelisauroids do
not form a clade to the exclusion of birds and other 'traditional'
tetanurans. In this situation, the Abelisauroidea would presumably be the
sister taxon to Tetanurae. Under this topology, Holtz's (1994)
Neoceratosauria (MRCA of _Ceratosaurus_ and Abelisauridae and all its
descendents) would therefore include all of Tetanurae too. Sereno (2005)
rates Neoceratosauria as 'inactive', and AFAIK has no clade solely for
_Ceratosaurus_ and abelisauroids within traditional Ceratosauria (i.e.,
including coelophysoids), which is strange. He may be assuming that the
days of a Coelophysoidea-_Ceratosaurus_-Abelisauroidea clade are numbered.
Even though he found such a clade in his _Rugops_/_Spinostropheus_ paper.
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