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Re: Lemurs and Feathers



In a message dated 6/19/01 2:53:11 PM EST, david.marjanovic@gmx.at writes:

<< When it's sophisticated enough, IMHO, but not earlier. For maneuverability,
 rather slight movements of e. g. the hands should be enough, and thrust in a
 glider... just jump off with more force! :-) (Not to mention that a
 parachuter tries to decrease thrust by definition.) >>

I don't think we have anywhere near exhausted the scenarios for the 
development/evolution of wings >directly< for flying, by incremental 
improvements in a feathered forelimb. Yet we have scenarios of wings 
developing for brooding and wings developing for underwater locomotion before 
being exapted for flight. I think people have become too enamored of the 
exaptation concept and are throwing it at avian flight with altogether too 
much abandon, without looking at the common sense of the situation. Does it 
make sense for an animal to evolve wings for brooding, only to have them 
happen to be perfect for flight? Does it make sense for an animal to evolve 
wings for swimming underwater, only to have them happen to be perfect for 
flight? This reeks of miracle. Why not simply have the animal evolve a 
rudimentary wing from a feathered forelimb that helps it to negotiate in an 
arboreal lifestyle, and then have these selfsame wings gradually improve, 
until they're capable of sustained flight? These wings could easily be 
exapted for brooding, underwater swimming, whatever you like, at any stage of 
the scenario, as many times as you like.