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birds and avians again

Jaime and George,
I tend to agree with Mike, and to me the traditional system (a modification thereof) is looking better and better. And the thought of making a clade Thecodontia is horrifying (thecodonts have always been a paraphyletic group and should remain so).
Once some dust has settled some years down the road, perhaps Aves will need to be expanded somewhat to include various coelurosaur groups, but I doubt that a massive expansion will catch on (especially if protofeathers and scutes are found to be closely-related variations on a theme). In the meantime, the Archaeopteryx anchoring seems to be fine (and if Dave Marjanovic is correct, this Archaeopteryx anchoring might automatically force us to include dromaeosaurs and various other maniraptors in Aves). I can sort of imagine Tyrannosaurus possibly being called a primitive "giant ground bird" in the future, but calling sauropods (even fuzzy ones) "birds" would be extremely hard to swallow.
From: "Jaime A. Headden" <qilongia@yahoo.com>
Reply-To: qilongia@yahoo.com
To: dinosaur@usc.edu
CC: Dinogeorge@aol.com
Subject: Re: Archosaur Origins...was:MESENOSAURUS ERRATA.
Date: Thu, 30 Aug 2001 22:39:10 -0700 (PDT)

George Olshevsky (dinogeorge@aol.com) wrote:

<I see nothing contradictory in the system I outlined. What could be simpler? If it's more closely
related to modern birds than to any other animals, why not call it a bird (or, if you like, bird
sensu lato)?>

I see this is an aesthetic statement, so perhaps we should persue this ... no ornithologist (all
the thousands of them) would agree or accept calling *Titanosaurus* a bird. It isn't, in any sense
of the word, which is fairly limited. Typically, taking an animal like *Heterodontosaurus* and a
pigeon *Columba*, one can easily tell down to the first grader and the collegiate professor of
law, which one is a bird. This is less stable when we pick *Velociraptor* and *Columba*, but it is
not as similar to *Diplodocus* and *Columba*. Whether one person would want to rename this Aves
based on some "simpler" way of providing a stem-based system, based only on living groups, is
inherently unstable and prone to dragging the vernacular with it, as you express to anticipating.

I cannot see this as a valid system based on an apparently aesthetic-driven stem-based living
groups, and using the names for these most inclusive groups as vernacular-laden terms. If so, then
use the easthetically pleasing Thecodontia again? Just give it a firmer definition....

===== Jaime A. Headden

  Where the Wind Comes Sweeping Down the Pampas!!!!

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