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Re: Tetanurae

On 12/7/06, Tim Williams <twilliams_alpha@hotmail.com> wrote:
Mike Keesey wrote:

>I realize Scott and David already know this, but I'll emphasize the point,
>anyway: _Tetanurae_ is a
>branch-based clade, so its basalmost members are probably virtually
>indistinguishable from the basalmost membes of the sister clade,
>_Ceratosauria_. Also, of course, _Tetanurae_ and
>_Ceratosauria_ are equally old. (This is true by definition; it doesn't
>matter whether coelophysoids are ceratosaurs or not.)

Right.  Ceratosauria is defined to *include* _Ceratosaurus_, and Tetanurae
is defined to *exclude* _Ceratosaurus_.  Thus, they have to be sister taxa.

We could conceivably recover a phylogeny in which traditional Ceratosauria
is paraphyletic, with coelophysids, dilophosaurids, ceratosaurids, and
abelisauroids as successive outgroups.  In this case, abelisauroids would be
basal tetanurans!

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
Bonaparte 1985.

Andreas Johansson

Why can't you be a non-conformist just like everybody else?