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At 10:59 AM 6/21/00 +0000, Jeffrey Martz wrote:
that it was more convenient to lump them as a big group.  Thecodontia may be
paraphyletic in stead of polyphyletic, but it is still a trash can.

It does seem so, but for reason independent of its being paraphyletic.

     Personally, I tend to agree that taxonomy shoud include paraphyletic
groups, BUT only if they are useful and make a meaningful distinction
between groups with a distinctly different suite of features or habitats or
whatever.  This certainly does not describe "Thecodontia".  What do
aetosaurs, rauisuchians, phytosaurs, ornithosuchians, erythrosuchians,
proterosuchians, proterochampsids, and Euparkeria all have in common with
each other that unifies them and makes them significantly different from
both crocodilians and dinosaurs?

Good point. Thecodontia as a paraphyletic taxon may well not meet the Ashlock criterion of maximizing information content. I am now convinced that particular taxon is dubious.

May the peace of God be with you.         sarima@ix.netcom.com