RE: Falsification of Homology [was: Re: Prum in latest Auk: Feduccia's arguments are "a rhethorical sham"]

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Jonathan R. Wagner
>
> Thomas R. Holtz, Jr. wrote [paraphrasing Richard Prum ]
>
> > * [Feduccia's] hypotheses of feather origins ("Elongate scale
> theories of
> feather
> > evolution were falsified on the basis of developmental evidence
> more than
> a
> > century ago, [...]
>
> In all fairness, I would argue that developmental evidence CANNOT
> falsify an
> assertion of homology. If you allow this, then you disallow the
> possibility
> that development can evolve. See De Quieroz's paper on the ontogenetic
> criterion for determining character polarity, and the wealth of literature
> on the interface between development and phylogenetic systematics.

What isn't clear from the very short quote was that the specific
falsification done had to do with the two planar surfaces represented by
scales are non-homologous to the two planar surfaces represented by
feathers. (To paraphrase, the dorsal surface of the feather is homologous to
both the dorsal and ventral surface of a scale, and the ventral surface of
the feather is homologous to internal (rather than external) surface of a
scale).

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796