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Re: Cladistic taxonomy (was Dietary factors)
On Tue, 8 May 2001, Ken Kinman wrote:
> I'm afraid that there is a stalemate between cladists (who say birds
> ARE dinosaurs) and the rest of us (who say birds are dinosaur descendants).
> When you remove a group of descendants (e.g. birds) from its ancestral group
> (e.g. reptiles, and dinosaurs in particular), the removed group is called an
> exgroup, and the rest of the ancestral group is labelled paraphyletic. Most
> cladists have been taught to regard "formal" paraphyletic groups as
> unnatural, to be discarded with the truly unnatural (polyphyletic) groups.
As I hope my previous response pointed out, Mark Shelly was actually
referring to several paraphyletic groups, none of which were non-avian
_Dinosauria_. These are more conveniently termed under the cladistic
system than the traditional system.
> The Catch-22 is that they keep adding more and more formal clades,
> which we must learn in order to apply their qualifiers,
How many new dinosaurian clades have been named in the past few years?
> and worse yet, even the cladists don't agree among themselves.
> "For example, the word dinosaur was not previously problematic--it was
> universally understood.
Tell that to Bakker (who is not a cladist).
> Mike Keesey has recognized this problem and recommended that some of
> these terms not be formally defined under PhyloCode, and use
> alternative cladistic terminology, such as Ostei instead of
> Osteichthyes, and Sauropsida instead of Reptilia.
_Sauropsida_ and _Reptilia_ are different clades. I tossed out the idea of
dubbing the latter "Neosauropsida" instead, but apparently Benton has
already proposed _Eureptilia_.
T. MICHAEL KEESEY
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