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Re: Tetanurae

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!

Speaking of abelisauroids, Jerry Harris wrote:

Coria, R., Currie, P.J., and Carabajal, A.P. 2006. A new abelisauroid theropod from northwestern
Patagonia. Canadian Journal of Earth Sciences 43(9): 1283-1289.
I don't have this one yet, and so don't know what, if anything, is the name of this new beast.

The authors aren't sure on this point either. A new genus name appears in the cladogram, but isn't mentioned in the text.



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