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Re: Steadman's review of Mesozoic Birds






From: DinoBoyGraphics@aol.com
To: dinosaur@usc.edu
CC: vindexurvogel@hotmail.com
Subject: Re: Steadman's review of Mesozoic Birds
Date: Fri, 30 Jan 2004 19:07:40 -0500

Ok, I had to jump in here"

>>>"but it is equally astonishing to see the very idea that
the theropod hypothesis is incorrect, relegated to the realm of quasi-creationist pseudoscience, and with it the denigration of an entire discipline (ornithological systematics)."<<<


You misunderstood what Prum said. It is not the IDEA of non-theropod avian origins that isn't scientific, it is the methodology employed by Feduccia, Martin, et al. that borders on pseudoscience. Evidence willing, the debate should continue, but not by recycling errant ideas. You cannot point out your favorite character that crocs (or prolacertiforms, or whatever non-theropod)share with birds and then ignore a much more bird-like example in nonavian theropods and pretend it is science (e.g. croc tooth replacement). You cannot claim that the pretibial bone absolutely cannot be the same as the ascending process of the theropod astralagus even though birds show a wide range of develomental origin for that condensate (including...the astralagus!) and pretend you are doing science. You can't keep saying "no birds are not related to theropods, but we can't tell you who they are related to becasue we haven't found them yet" and pretend to be doing science. And you can't claim that the time gap (20-40 million years depending on when the claim was made during the last 30 years) means that birds could not have evolved from dinosaurs, even though the "thecodonts" in question have a 60+ million year gap, and pretend you are doing science.

You certainly can't spend 20 years publishing papers explaining how stupid the proponents of the theropod-bird connection are for thinking that a dromaeosaur looks anything like a bird ancestor, and then when feathered dromaeosaurs are discovered claim that all maniraptorans are birds but not dinosaurs and not expect at least a little flack from your collegues.

Martin and Feduccia have made careers out of making claims long after they have been falsified in other papers (like croc ear and tooth replacement "homologies" that supposedly don't exist in dinosaurs, or claiming that double- shelled eggs in dinosaurs prove that birds didn't evolve from them, even though double-shelled eggs all come from dinosaurs that are not thought to be bird ancestors). They have continued to make loud claims in the popular media despite making claims long since falsified. It is simply ridiculous.

I have known Larry Martin for almost a decade, and he has always been nice to me. I wish him all the best in life, but the charade has to stop. This does not mean that there isn't a lot of zeal and animosity on the dinosaur-bird side, and some cladists are extremely attached to their particular cladogram. This personal attachement is often what drives science, but it can certainly be acrimonious. It is ture that lots of good science was done before cladistics was invented, but that does not excuse ignoring modern techniques when conducting modern research.

Finally, this does not and should not "denigrate" ornithological systematics. First, many, if not most published ornithology textbooks support the theropod origin of birds, so it is not like ornithologists are lining up behind Feduccia. Second, all modern phylogenetics is based upong the foundation that traditional systematics built. Of course much of the original work will turn out to be somewhat wrong, and some of it will be radically wrong. As we try to sort out the differences between morphological and genetic data, there are sure to be many more false starts waiting along the way. None of that should denigrate those whose ideas are falsified becasue of new data or new techniques. Ornithologists labored long and hard (and no dount with much care) to get us to this point, and their work is important and justified regardless of what details may be falsified through time.

I guess what I'm getting at is: it's understandable to lament the excesses in personality sometimes seen on both sides. And if the preponderance of the data had fallen in with Feduccia and Martin, some of the bird-dinosaur people may have fallen into similar fringe reactions. But that does not excuse, on a scientific level, the belief that there is any significant debate left with the data at hand. Without new (and radical) information coming to light, support of the non-theropod origin of birds is an excersize in futility (or worse, ego). I, for one, eagerly await new fossils that could cast a light in favor of non-theropod avian origins. But I also have great doubt that they exist.


Scott Hartman Zoology & Physiology University of Wyoming Laramie, WY 82070

(307) 742-3799


A well stated and moderate post, Mr. Hartman. I would only add that I do not think the lack of fossil resolution for the thecodont hypothesis to be as crippling as some seem to feel it is. The real errors are to be found elsewhere.

JGK

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