RE: FEDUCCIA AND THE NEW YIXIAN DINOS

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

At 06:39 AM 6/25/98 -0400, James "Wiwaxia" Sutton wrote:
>I have read on this newsgroup a range of understandings of the
>way science works and it seems rather limited, especially when it comes
>to this issue.  Science does not work through the gathering of data to
>support a theory (as I gather that many believe based on their posts) but
>through data which do not support it in an attempt to negate or falsify it.

I certainly agree with this.

>To do
>that is what science is all about and, it seems to me, Feduccia has acted
>in the highest tradition of the scientific spirit in that he actually tries to
>refute the theory that everyone else seems to be attracted to like moths
>to a flame.  He deserves a lot better personal consideration than he has
>been given by many on this list.

IF his work to propose alternatively theories had been done in the method of
modern comparative biology, and IF he would drop particular arguments once
they had been refuted, THEN his work on this subject would deserve better
consideration.  In some cases, for example the homologies of the embryonic
development, he and his coauthor have raised some very valid points of
debate.  This particular line of evidence, which does not (as he state)
refute the dinosaurian origin of birds, at least provides some question as
to changes in developmental patterns in evolution: an interesting and useful
topic to consider.

However, his continued use in the public press of such refuted lines of
argument as the supposed "time gap", the "trend towards shorter arms in
theropods", the "presence of the semilunate carpal in only four dinosaurs",
the "presence of the furcula only in birds and oviraptorosaurs", the idea
that non-serrated teeth cannot evolve from serrted teeth, etc., demonstrates
that (in these cases) he is not operating under the rules of science.  These
particular lines of argument have been refuted by the evidence, and should
be abandoned.  That doesn't mean he (and others) shouldn't be looking for
new lines, of course.  I welcome such new lines.

>He is surely not ignorant and I think most of you know it.

In some subjects, he is certainly not.  However, his most recent book on the
subject of bird origins (The Origin and Evolution of Birds, 1996, Yale Univ.
Press) and recent interviews contains factual errors and out of date
information with regard to non-avian archosaur anatomy, paleontology, and so
forth.  Is he alone in some of these errors?  No.  However, that doesn't
excuse him.

>And don't be so smug about these latest discoveries.  They may require
>interpretation later on in the light of new interpretations and "new"
>fossils.  Just as me and my buddy Hallucigenia have been reinterpreted,
>these fossils may be reinterpreted by later scientists in light of a different
>paradigm.  There may well be lurking in these rocks something we don't
>yet know about that will screw things up.

While that may be, this isn't a case like Hallucigenia.  In the 1970s,
Burgess Shale invertebrates were scientifically examined by a small handful
of invertebrate paleontologists, one paper of which suggested the position
we all knew and loved.  There had been little critical examination of the
evidence in the meantime, and the discovery of the Chinese armored lobopods
reversed that position.

In the case of bird origins, there are considerably greater number of
scientists involved, working together or independantly, using many different
analytical techniques, on many different specimens of many different taxa.
But for a small persistant cluster of workers, the lines of evidence have
dovetailed to a particular answer: birds are derived from dinosaurs.

>For instance, has a
>microscopic study of the bones been done?  Suppose these bones have
>a peculiar histology that will require explaining with a different paradigm
>from either Feduccia's point of view or yours.

Indeed.  And, if and when such evidence arises, it will require new
interpretations.  Until then, we must make do with the theory that best
explains the most data.

>There are too many things
>we just do not know yet and we must never reach the point where we
>so hypocritically say that we have "proved" the theory. A single datum
>not explainable by the theory brings it down.

A curious statement.  So, any time a new potential synapomorphy between
typical theropods and birds is discovered, Feduccia is allowed to explain it
away as convergence, and it thus bolsters his theory?  However, any time he
suggests a structure unique to birds, or one found in birds and some other
taxon but demonstrated not to occur in theropods (note: the latter HAS NOT
BEEN DISCOVERED - interesting, ne?), he can claim it therefore totally
overturns the remaining evidence for a dinosaur-bird connection?

Very interesting rules of evidence to operate by, I'd think you'd have to admit.

Incidentally, overturning an hypothesis is not evidence for your own.  In
point of fact, neither Martin nor Feduccia have yet published an explict
phylogenetic hypothesis or hypotheses of the taxon or taxa which they
consider closest to birds.  (Multiple working hypotheses are fine, of
course).  Feduccia has suggested that the "derivation of birds... from small
arboreal Triassic thecodonts is intiutively pleasing...", and mentions some
arboreal and/or avian-like features in Longisquama, Scleromochlus,
Megalancosaurus, and Cosesaurus, but does not identify how he considers
these particular forms and other basal archosauromorphs to be related to birds.

Feduccia (and Martin, and others) should publish an explicit phylogenetic
hypothesis or hypotheses, so that these can be subjected to the same style
of critical analysis that the theropod origin of birds has been.  Is that
asking too much?

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661