Re: Archaeopteryx (rant)

["Tim Williams" <twilliams_alpha@hotmail.com>]

Dinogeorge@aol.com wrote:

> Just because a system has been used incorrectly doesn't invalidate the 
> system
> itself. We can simply learn how to use it correctly. For example, one class
> (Reptilia) can give rise to another (Aves); why not? Descent doesn't mean 
> you
> >must< include the descendant group within the ancestral group. And as far 
> as
> rank goes, it's purely arbitrary, so why not simply assign the groups their
> ranks forevermore and be done with it?

What a ghastly idea!

Look, if you want to keep the Linnaean system around for the purpose of 
classification - Linnaean stamp-collecting, if you will -  then go ahead.  
But please - PLEASE! - don't incorporate it into any evolutionary or 
phylogenetic discussions.  Statements like "one class (Reptilia) can give 
rise to another (Aves)" are not helpful in communicating ideas about 
evolution.  The term "class" is in itself a statement that a certain group 
has attained a level of organization superior to that of its ancestral 
"class".  These ranks (and what they imply of the natural process) have no 
place in evolutionary discourse.

On that note, if  you wish to retain unnatural (paraphyletic or 
polyphyletic) groups like Thecodontia, Condylarthra or Protozoa, simply 
because they make it easier to classify difficult-to-handle "primitive" 
taxa, then knock yourself out.  All the weird Triassic archosaurs (those 
that are obviously not dinosaurs, pterosaurs and crocodiles) can be dumped 
in the Thecodontia, without having to expend time and energy figure out who 
might be related to who.  But these wastebasket groups should be kept 
separate from any scientific discussion of evolution.  To say, "birds 
evolved from thecodonts" reveals nothing - except for the fact that the 
author has no idea what the closest relative of birds might be.



Tim

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