[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
RE: Steadman's review of Mesozoic Birds
From: "Tim Williams" <email@example.com>
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
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
and with it the denigration of an entire discipline (ornithological
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.
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
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.
Check out the coupons and bargains on MSN Offers!