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Re: Lemurs and Feathers

On Tue, 19 Jun 2001 16:47:56  
 Dinogeorge wrote:
>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.

This is very scary, as I am agreeing with George more and more these days :-)  
I absolutely agree with what George (and Tim) have said today.  When I first 
became interested in dinosaurs I didn't care less about the avian evolution 
debate.  However, I have been doing some more reading on it lately, and must 
now confess that the evolution of flight, feathers, the wing, the wing flip, 
carina, etc. do intrigue me.  

I definitely believe that wings evolved in an arboreal glider.  It is the 
simpliest explanation, and makes the most sense.  While I certainly cannot 
dismiss it, having the wing evolve for underwater flight is too difficult an 
explanation.  I subscribe to Occam's razor here.  It is much easier to envision 
wings evolving as an evolutionary aid to gliding animals.  These wings, 
adaptations to the arms, could have been put to very good use as structures to 
control flight, provide steering and direction, to break falls, etc.  Only 
later did they likely become modified into structures used in underwater 
flight, as in penguins.  

But, I also agree with Tom Hopp.  I haven't read his paper, and definitely 
cannot put his idea aside.  I just wish I could get my hands on that damned 
volume.  Tom, if you have a copy of the paper on your computer, feel free to 
e-mail it to me (use brusatte@theramp.net , please).  I would be glad to read 


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