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Re: Feduccia ORIGIN



At 12:57 PM 1/9/97 -0500, Caitlin Kiernan wrote:

>In its entirety, in the proper context of Fediccia's argument, it does make
>sense. That's not to say he's right or that I'm accept the argument as valid.
>He isn't saying that an "already-flying" animal is required for the
>development of feathers, but that feathers evolved not from a
>short-forelimbed, cusorial predator (such as an early dinosaur), but from an
>arboreal, long-forelimbed diapsid.

However, Feduccia (and, to be fair, many others) cannot separate the
"ground-up"/"trees-down" debate from the "dinosaur"/"weird-ass Triassic
diapsid" debate.  Feduccia would reject as nonsense birds coming from any
dinosaur, even if it were possible that small coelurosaurs climbed in trees
(and were thus arboreal, long-forelimbed diapsid).

>He's saying that it's difficult (and perhaps impossible) to
>construct a sound model whereby feathers evolved in a ground-up
>scenario.

And thus?  Just because we haven't constructed a model for a particular
origin scenario does not mean that we don't have profound anatomical
evidence supporting particular phylogenetic relationships.

Would our understanding that humans, chimps, and gorillas are closer
relatives be any less secure if we didn't have the various functional
origin-of-humans models to choose from?  The morphological (and molecular,
and behavioral) data are there to support the relationship, regardless of
the origin scenario(s) favored at present.

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

"To trace that life in its manifold changes through past ages to the present
is a ... difficult task, but one from which modern science does not shrink.
In this wide field, every earnest effort will meet with some degree of
success; every year will add new and important facts; and every generation
will bring to light some law, in accordance with which ancient life has been
changed into life as we see it around us to-day."
        --O.C. Marsh, Vice Presidential Address, AAAS, August 30, 1877