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Re: Steadman's review of Mesozoic Birds
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 c!
im 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.
Zoology & Physiology
University of Wyoming
Laramie, WY 82070