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Re: Resolving the Digit Loss Debate?



In a message dated 6/10/01 4:13:31 AM EST, qilongia@yahoo.com writes:

<< My point is this, unless it serves a function to control air while the 
organism in in flight, or gliding, then it's not a wing. Not even an airfoil. 
Even a ceratosaur couldn't get it's arm into the possition to allow any form 
of as yet unknown integumentary structures to effect the air. >>

Early dinobirds had five loci for airfoils on their body: the tail and the 
four limbs. The first of these to develop an airfoil function must have been 
the tail, mainly because it's simply the part that needs the least 
modification to become one: just grow a fringe of feathers and voila. With 
regard to the limbs, they don't have to be able to extend sideways from the 
body (let alone up over the back as in avialan birds) in order to have an 
aerodynamic function; given a suitable fringe of feathers, they can be 
aerodynamic at pretty much any angle. We're not looking for perfect flight 
here, just something to mollify the effects of a fall (as in fluttering) or 
to help control the midair course of a leap. The forelimbs would naturally 
have served to arrest the animal at the end of a leap, so there would be a 
tendency to retain/improve the grasping function for this new role.