[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Bad as opposed to BADD



In a message dated 96-10-26 18:00:19 EDT, mrowe@indiana.edu (Mickey P. Rowe)
writes:

> Despite what he might have us believe, George does not hold the corner
> on the market on the idea that flight evolved first in arboreal forms.
> I suspect that idea is older than George is (it's most certainly
> decades older than "BCF").

The trees-down theory of the evolution of flight must be as old as Darwin and
Huxley, though it might be due to their German contemporary Gegenbaur. At
this point I can't be more definite because, oddly, I haven't paid much
attention to the origins of the trees-down theory.

The idea that dinosaurs evolved from arboreal archosaurs seems to have
originated with a 1911 work by German paleontologist Othenio Abel. As luck
would have it, it is alphabetically the very first entry in the bibliography
for _Mesozoic Meanderings_ #2 third edition:

Abel, O., 1911. "Die Vorfahren der Vogel und ihre Lebensweise," Verhandlungen
der Zoologische und Biologische Gesellschaft Wien 61: 144-191.

When I wrote up BCF the first time, in the first edition of _MM_ #2, I hadn't
yet read this work. Indeed, it is quite difficult to find on this side of the
Atlantic, and I still only have photocopies of those pages directly relevant
to dinosaur origins. So in this sense I arrived at my conclusions
independently of Abel and more because I read Greg Paul's short paper

Paul, G. S., 1984. "The Archosaurs: A Phylogenetic Study," in Reif &
Westphal, eds., 1984: 175-180.

in

Reif, W.-E. & Westphal, F., eds., 1984. Third Symposium on Mesozoic
Terrestrial Ecosystems, Tubingen 1984, Short Papers, Attempto Verlag,
Tubingen: vi + 259 pp.

Evidently nobody took Abel seriously, particularly Huene, whose well-known
dinosaur phylogeny ruled the first third of the 20th century, and Heilmann,
whose major work on the phylogeny of birds

Heilmann, G., 1927. The Origin of Birds, D. Appleton & Co., New York: viii +
210 pp.

effectively squashed the idea that dinosaurs and birds were intimately
related. A few paleornithologists (Lowe, Beebe) continued trying to make
everyone else see this relationship, but their works had other problems and
nobody took them seriously, either. For a review of the various ins and outs
of dinosaur-bird phylogeny, I >strongly< recommend Larry Witmer's exceptional
paper

Witmer, L. M., 1991. "Perspectives on Avian Origins," Chapter 12 of Schultze
& Trueb, eds., 1991: 427-466.

in

Schultze, H.-P. & Trueb, L., eds., 1991. Origins of the Higher Groups of
Tetrapods, Comstock Publishing Associates (Cornell University Press), Ithaca,
New York: xii + 724 pp.

which is itself a superb reference on the groups in its title.

>  The message to which I'm responding completely confuses the
> distinction between the arguments "how did flight evolve" and "what
> is the phylogenetic position of birds with respect to other
> dinosaurs".  I suspect most of us have problems with BCF because of
> its claims about the latter.  Its claims about the former are not so
> far fetched.

BCF asserts that flight evolved in birds from the trees down. Some BADD
paleontologists, and almost all paleornithologists, agree.

BCF asserts that theropod dinosaurs were the giant cursorial descendants of
the arboreal archosaur lineage some of whose small, arboreal members
eventually evolved into birds. With the discovery of the Madagascar "flying
dromaeosaur" (elongate, stork-like fore and hind limbs; feather papillae on
the ulna; killer claw on the second pedal digit) unveiled at Cathy Forster's
talk at this year's SVP, it is virtually certain that Greg Paul's idea that
dromaeosaurs were the flightless descendants of [pre-]archaeopterygids is
correct. BCF extends Greg's idea to the less birdlike theropods and asserts
that they, too, were giant, cursorial descendants of "pre-archeopterygid"
dino-birds: small, _Archaeopteryx_-like archosaurs that were technically
tree-dwelling, feathered dinosaurs. "Dino-birds" is my informal name for
those archosaurs on and close to the lineage that led from the common
ancestor of crocodilians and birds to the common ancestor of _Archaeopteryx_
and birds.
 
> Despite the tone of the message to which I'm responding, George is not
> a lone heretic with all of his ideas about the history of birds.
> Furthermore there is no singular "BADD" against which "BCF" stands in
> contrast.  George makes a lot of claims.  If you were to poll a bunch
> of professionals with a list of George's claims (preferably with no
> indication of how the list was generated) you'd find that a lot of
> paleontologists would agree with some of them.  Of those finding some
> agreement with George, not all would agree on the same items of my
> hypothetical list.  That's the way science goes, particularly in areas
> where data are sparse.

More and more paleontologists are reading the earlier _Mesozoic Meanderings_
#2 editions and coming to see that, yes by golly, there is some sense to BCF.
One problem is that _MM_ #2 had such a limited press run. I fully expect that
the central idea of BCF, that of small, acronomic archosaurs as common
ancestors of dinosaurs and birds, as originally put forth by Abel and as
modifed by the past couple of decades' research strengthening the
dinosaur-bird connection, will become the dominant paradigm of dinosaur
evolution. BADD, inchoate mass that it presently is, will eventually "merge"
with BCF: consciously or unconsciously, it's happening even as we exchange
these e-mails.
 
> George, please get over the martyr complex.  I think you're doing the
> readers of this list a gross disservice every time you try to pass
> yourself off as the only person making any sense. 

What "martyr" complex? >Evangelist< complex, if anything, seems closer.