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Re: Non-serpentine lacertids (was RE:WHAT'S GOING ON?)



On Mon, 3 Jul 2000 Dinogeorge@aol.com wrote:

> In a message dated 7/3/00 1:00:37 PM EST, cbrochu@fmnh.org writes:
> 
> << It is never natural to remove a descendent from a supraspecific taxon. >>
> 
> I'd like to see a good reason for this opinion. It lies at the heart of the 
> differences between cladistic taxonomies and non-cladistic taxonomies and the 
> disputes between their respective adherent taxonomists. To me, a "natural" 
> group must include its common ancestor but need not include all the 
> descendant subgroups of this common ancestor (though it usually does). The 
> criteria for removing such a subgroup into an independent taxon are 
> qualitatively no different from the criteria that distinguish one species 
> from another. There is no difference in phyletic information content between 
> the statements "birds are dinosaurs" and "birds descended from dinosaurs." 
> Why should one be preferred and the other rejected?

Because removing Aves from Dinosauria precludes other distinctions. It
says "this distinction is more importent than other distinctions along the
lineage". Why should it be cut at Aves? Why are the distinctions between
_Archaeopteryx_ and basal Eumaniraptora more important than the
distinctions between basal Maniraptoriformes and basal Coelurosauria? Or
between basal Ornithodira and basal Archosauria? Or between basal
Neornithes and basal Carinatae?

All of these distinctions are important. Placing more significance on one
than on the others undermines our understanding of evolutionary history.

____________________________________________________________________________
T. Michael Keesey <tmk@dinosauricon.com> | AIM <Ric Blayze> | ICQ <77314901>
                 My Worlds <http://dinosauricon.com/keesey>
                 The Dinosauricon <http://dinosauricon.com>