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

In a message dated 96-02-08 21:37:19 EST, pharrinj@PLU.edu (Nicholas J.
Pharris) writes:

>But do you see where I'm coming from?  The way I see it, birds *can't* be 
>"derived enough" to "warrant being called something different", just as 
>neither I nor any of my descendants can ever not be a mammal and a 
>primate.  A bird can't change itself enough to erase who its ancestors 
>were, or what its closest relatives are.  

When a paraphyletic taxon is created, this acknowledges that at least one
descendant group includes organisms morphologically or in some other
significant way very different  from the parent group. Nobody is saying that
the excised group is _unrelated_ to the parent group...just that the group is
significantly different.

>In my book, the purpose of 
>taxonomy is to illustrate what is related to what.  You can't do that if 
>you go around ripping groups out of their proper places in the tree of 
>life and pretending that they've become something else.  

This is not the only purpose of taxonomy. We also group similar organisms as
a form of shorthand when discussing their common features and properties.
Nobody's ripping the groups out of their proper places in the tree of life!
Systematists just put boxes of various kinds and names around the branches,
is all. The branches remain intact. Sometimes it makes sense to name the
branches, other times it makes sense to name different portions of the tree.