Re: Tetanurae

[Tim Williams <twilliams_alpha@hotmail.com>]

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.
[snip]
> 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.

Cheers

Tim

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