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

feathers as N2 excretors



Message text written by INTERNET:brush@uconnvm.uconn.edu
>Reichholf argues that rather than convert this S in feather amino acids to
hydrogen sulfide (H2S) which is highly toxic, the S-containing AA's
represent a pathway to excrete the ma
terial where it is insoluble and therefore of no danger to the body. He
rationalizes the annual molt as a detoxification mechanism.
He makes some other arguments regarding dietary energy that are difficult
to accept. He uses these to  establish 'excess" proteins as related to the
formation of keratins. He then relates this to the proposed excretory
function of feathers.<

        My problem with this idea (at least, as Reichholf has written it)
is that I fail to understand why evolution would guide early feathered
"protobirds" into a position where they are producing excess sulfate (or
anything else, for that matter) in their bodies, thus requiring the
excretionary adaptation (for which feathers seems excessive).  It doesn't
make much sense to me that a population of organisms would evolve into a
position where they are producing toxins to themselves.  Also, given that
the vertebrate body has evolved an elaborate system of organs for
eliminating wastes, producing a wholly new (and rather complex) one seems
excessive (that is, not very parsimonious).

        Still, his idea is novel (at least to me -- does anyone have
references for where this idea has been proposed before)?


                _,_
           ____/_\,)                    ..  _   
--____-===(  _\/                         \\/ \-----_---__
           /\  '                        ^__/>/\____\--------
__________/__\_ ____________________________.//__.//_________

Jerry D. Harris                         (505) 841-2865
Fossil Preparation Lab                
New Mexico Museum of Natural History        
1801 Mountain Rd NW                           
Albuquerque  NM  87104-1375             102354.2222@compuserve.com