Re: Archaeopteryx (rant)

[Dinogeorge@aol.com]

In a message dated 6/18/03 7:55:30 AM Pacific Daylight Time, 
twilliams_alpha@hotmail.com writes:

<< On that note, if  you wish to retain unnatural (paraphyletic or 
 polyphyletic) groups >>

There's nothing unnatural about a paraphyletic group. You simply form a 
paraphyletic group by excluding one or more clades from a more inclusive clade. 
It's no more unnatural than requiring a group to comprise all included 
descendant 
clades.

The problem is that cladists require taxonomic groups to be clades, which is 
as arbitrary a convention as any other in taxonomy. What makes a group 
natural, that is, taxonomically valid, is descent from a common ancestor--and 
the 
common ancestor itself need not even be included. That's all that's necessary 
for 
biological taxonomy.