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Re: Quo vadis, T. rex? [long]

On Fri, 9 Feb 1996 Dinogeorge@aol.com wrote:

> By the way, tell the above to crown-group cladists sometime. They frequently
> name major clades on the basis of their extant surviving groups. E.g.,
> Archosauria = last common ancestor of extant Crocodylia and Aves + all its
> descendants.

You know very well that the groups do not have to be extant.  Crocodiles 
and birds are simply well-known and happen to be as far separated as any 
two archosaurs can be.  One could just as well define Archosauria as "the 
last common ancestor of _Anserimimus_ and _Desmatosuchus_ (just to be 
obscure) + all its descendants", if one were so inclined.

Nick Pharris
Pacific Lutheran University
Tacoma, WA 98447

"If you can't convince them, confuse them." -- Harry S. Truman