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Feathers vs patagia,...was:Re: Paleo Find ("Millennium Man")



-----Original Message-----
From: David Marjanovic <David.Marjanovic@gmx.at>
To: The Dinosaur Mailing List <dinosaur@usc.edu>
Date: Friday, January 05, 2001 4:49 PM
Subject: Re: Paleo Find ("Millennium Man")


(snip)

>The arboreal hypothesis has a few big problems. One is the transition from
>parachuter to glider (not actually necessary) and the transition from
glider
>to flyer (necessary). Why don't birds have ordinary patagia? Pterosaurs had
>hair (or was it dinofuzz???) and developed patagia instead of wing
feathers.


(snip)

Perhaps birds started out with larger patagia. It is my opinion that
feathers developed initially for better insulation. Contour feathers would
have been an improvement over hairlike  protofeathers. Also, a large
patagium would have contriburted to heat loss.  Another advantage would be
that a feathered wing could beat more rapidly, due to the fact that air
could slip through the feathers on the upstroke.

This more rapid wingbeat could enable a hovering type motion, and enable
relatively soft landings on hard perches that gymnosperms would offer. (I am
assuming these were predominant trees in a colder enviorn). Pterosaurs seem
more likely to have made more clumsy landings on more flexible Cycad
branches.

These different enviornmental niches could have allowed birds to evolve
without being in direct competition with the already existing pterosaur
populations.