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Re: feathers as N2 excretors

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Message text written by INTERNET:Dinogeorge@aol.com

"Novelty of idea seems to be proposal that feathers had a metabolic origin,
which would >compel< their appearance by establishing some kind of prior
rather than simply accepting their appearance as a random fact of evolution
that became exapted a posteriori. Who knows whether, specifically, sulfate
excretion was necessary in protobirds--and, if so, what did protobirds do
about it before they had molting of feathers? That part of argument is
certainly questionable."

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        Well, whether or not one perceives feather evolution as a means of
excreting excess sulfate or as insulation, it's still a metabolic problem
-- one's just from the outside in ("it's cold outside, so evolve a means of
keeping warm inside") or one from the inside out ("there's too much sulfate
in here; get it outta here!")  Only the
feathers-originated-as-display-structures argument doesn't seem to be
directly metabolic.

        Your point about what did "protobirds" do about sulfate before
molting feathers is along the lines I was thinking -- again, feathers seem
to be a bit excessive for a problem with a zillion other, less complicated
solutions.  I intended to state that Reichholf's idea was novel simply in
the sense that it's nice to see people seriously thinking about the
problem, even after all this time!  8-D

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                     Jerry D. Harris
                 Fossil Preparation Lab
          New Mexico Museum of Natural History
                   1801 Mountain Rd NW
               Albuquerque  NM  87104-1375
                 Phone:  (505) 899-2809
                  Fax:  (505) 841-2866