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Feathers not for SO4^2- excretion



----- Original Message -----
From: "Larry Febo" <larryf@capital.net>
To: "David Marjanovic" <david.marjanovic@gmx.at>; "The Dinosaur Mailing
List" <dinosaur@usc.edu>
Sent: Sunday, March 25, 2001 3:18 PM
Subject: Re: Feathers for S excretion (very long)


> >There seem to be some misconceptions on this hypothesis onlist. First,
> >nobody says feathers evolved for sulfATE excretion -- this is water
soluble
> >and totally unproblematic AFAIK.
>
> But,.....if the protobird lived in an arboreal enviornment, and was
> developing protofeathers for insulation, this would indicate a
non-tropical
> enviorn, with only occasional rainfall. Under such conditions, it would
make
> sense for the development of longer scales for this sulfate excretion, as
> there was not sufficient water available to get rid of it in liquid urine.
>
>  Seems to present itself as a good arguement >>for<< the trees-down
> scenario,...no???

No IMHO. I'm not sure if animals can build up amino acids from sulfate at
all, if sulfate _ever_ occurs in so large amounts that it could make
problems, if sulfate can cause problems at all, and after all no living
animals seem to have problems with sulfate, AFAIK.

So if "the protobird" (or rather proto-ornithodiran?) did not live in an
arboreal environment, and was developing protofeathers to excrete
S-containing amino acids, this wouldn't indicate any climate, and though it
wouldn't be a good argument against trees-down, it certainly wouldn't be one
for it.