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RE: Steadman's review of Mesozoic Birds




From: "Tim Williams" <twilliams_alpha@hotmail.com>
Reply-To: twilliams_alpha@hotmail.com
To: dinosaur@usc.edu
Subject: RE: Steadman's review of Mesozoic Birds
Date: Fri, 30 Jan 2004 12:25:07 -0600

John Pourtless wrote:

it is equally astonishing to see the very idea that the theropod hypothesis is incorrect, relegated to the realm of quasi-creationist pseudoscience,

I have not seen the NTAB (non-theropod ancestry of birds) side of the debate characterized as "quasi-creationist". I have seen the word "pseudoscience" thrown around; but this not entirely unjustified, since NTAB is devoid of any really methodology as far as I can see. An evolutionary tree is given which alleges that birds arising directly from thecodonts, or birds+maniraptorans representing a distinct lineage from other dinosaurs (=MANIAC, as coined by M. Mortimer), and supporting characters are added to the tree afterwards - like hanging baubles on a Christmas tree.

and with it the denigration of an entire discipline (ornithological systematics).

Again, I have not seen this. Don't forget, Richard Prum is a card-carrying ornithologist. The debate is not simply paleontology vs ornithology.

From all I have seen the data which has been presented by the thecodont camp, though incorrect and framed in shoddy and at times outrightly specious contexts, is nonetheless there.

So is the hypothesis that endothermic vertebrates (birds and mammals) form a monophyletic group ('holophyletic' of your usage) called Haemothermia to the exclusion of ectothermic vertebrates. You reach a point when one hypothesis simply becomes unsustainable. I think NTAB has reached that point. Thus, I can understand the frustraton of paleontologists when the "birds are not dinosaurs" people get equal billing in the press. It reminds me of an astronaut responding to claims that the 1960's moon landings were faked.



Tim


Dalton (2000) compared the opposition to the theropod origin of birds to creationist tactics. At any rate, the difference is in the way in which phylogeny is reconstructed, and I am quite sorry to say that despite the vast utility of cladistic analysis, is not the solitary, immutable, flawless method for phylogenetic reconstruction to the exclusion of all others. Simply because a methodology is not cladistic, does not render it invalid.

As for the viability of the thecodont hypothesis...I do not not think it viable, that much is obvious, but there is enough data to suggest that perhaps, in some strange twist, it could be correct, and our understanding on the origin of birds and their evolution can only grow through continued debate on that very topic. If the theropod hypothesis is allowed to reign triumphant without challenge it ceases to be science and becomes precisely what Feduccia at his worst as called it, simple dogma. Indeed, revisions to the theropod origin of birds have arisen via the challenges presented to that hypothesis, and there is no reason to suggest that anything different will occur. We should be concentrating on the substance of the papers by those who disagree with this viewpoint, not the language with which they are written.

Prum's 2002 and 2003 articles in The Auk bother for me one principal reason, they propose (at least the former does) just as outlandish and absurd a situation as Feduccia's cladistic conspiracy, basically, that ornithologists are just too ignorant of paleontology to know the difference between hollow rhetoric and real science. The very assertion, however carefully phrased, is a slap in the face to a discipline which has produced some of the finest paleontologists of American history (e.g., the peerless Dr. Alexander Wetmore, Hildegarde Howard, and Pierce Brodkorb, among many others). Again we see excess to match excess, in a finely tuned symphony of absurdity.

JGK

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