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Final thoughts



 
    Here are my own final comments on our monthly installment of the "birds are NOT dinosaurs" debate...
    I've made the point in the past that in some situations, paraphyletic groups should be recognized for grades which differ in a generally conistant way in morphology, lifestyle, or whatever, from one or more descendant clades, simply because there is no way discuss such evolutionarily, ecologically etc. interesting groups using strictly monophyletic terms.  However, being based on rather arbitrary criteria, its hard to create tidy paraphyletic groups which can be broadly agreed upon; for this reason, they should be appraoched with caution.  They certainly can't be defined as tightly as monophyletic taxa, and definitions should remain flexible.  It probably gets easier at lower taxonomic levels because you are looking at smaller and therefore potentially less diverse groups that may easier to outline; genera are probably the most frequently encountered example of this, as any analysis which includes polyspecific genera is likely to have one or more turn out to by paraphyletic.
    However, I do NOT extend my tolerance of paraphyly to long accepted paraphyletic groups simply on the basis of familiarity, and here is why: As more fossils are found, paraphyletic groups which group generally morphologically similar taxa that differ in an interesting way may potentially become more clear and better understood (although the edges of the group are also probably going to become more fuzzy). 
    The same doesn't apply to familiarity, because it fades with time.  After another 50 years of people recognizing that birds are descended from dinosaurs, people won't give much of a crap about CALLING them dinosaurs, just as not many people today seem to give a crap about Apatosaurus supplanting Brontosaurus.  Everyone knows nowadays what Apatosaurus is, and the initial consternation stemming from familiarity with Brontosaurus is long gone.  By the same token, birds are already generally accepted to be descended from Dinosauria, don't really look very out of place among the broad but socially acceptable diversity of Dinosauria, and there isn't much that all "non-avain Dinosaurs" have in common with each other that excludes birds and justifies eventually them getting thier own name (Dinosauria) exclusive of birds.  Public and what professional consternation remains will fade as people become more familiar and comfortable with these facts.  When this happens, what do you suppose the next generation of vertebrate paleontologists will think of the "public familiarity" of another generation being used as a criterion for judging how organisms were grouped?
 
LNJ
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Procrastination is the thief of time- Edward Young
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Jeffrey W. Martz
Graduate student, Department of Geosciences, Texas Tech University
3002 4th St., Apt. C26
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