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Re: bauplan convergence



what I particularily like about this theory is that unlike plummetting
out of trees and running around on the ground like an idiot chasing
stuff, it explains FLAPPING behaviors better than anything else to
date.  (well ok, swimming strokes would give you symmetrical 'flapping'
motions as well, but won't get the bird off the ground)

An animal that leaps out of a tree does not make a natural flapping
motion; this behavior is best geared best for future gliders.  In
chasing prey on the ground only the most dimwitted hunter would start
flapping his arms around -and the flapping the arms around would not be
garanteed to be a symmetrical stroke.

The courtship and threat displays of animals with ornamental frufru on
their arms could lead to both symmetrical strokes AND situations where
launch is possible.  

Once you have an animal selecting for flapping ability AND an animal
that seeks out launch conditions, you have a PRIME candidate for flight.

-Betty Cunningham

Edels wrote:
>         I don't remember if I was the first to suggest it on list, but I 
> certainly
> promoted a particular version of it.  I suggested that perhaps the area
> where the proto-birds lived developed  a somewhat constant breeze (much like
> Aruba today), and in the course of courtship dancing and leaping, and the
> display of their feathers; some of the dancers and leapers were swept up in
> the winds, and were able to display higher and longer - obviously a
> favorable trait - sure to impress the ladies. :-)

> -----Original Message-----
> From:  Betty Cunningham
> I'm not positive but I think ibises do the hoppy flappy wing thing.
> Many birds such as grouse and chickens and so on do an out-streatched
> wing shuffleing dance thing to attract the babes.  Cranes do that
> holding back the head and spreading the wings thing as a courtship
> ritual too.
> 
> Wings are a major portion of MANY bird mating displays.  It seems
> likel;y that's what proto-feathered owings were for before flight.  And
> the hoppy flappy thing seems most likley to introduce launch situations
> to such animals.
> 
> I'd forgotten who suggested this onlist, but I didn't originate the
> idea.  It just makes a hell of a lot of sense to me.

> Martin Human wrote:
> > From: Betty Cunningham wrote
> > I still put a vote behind the protofeather sexual display hopping thing
> > for wing development; which is niether trees up or trees down, really.
> > It makes more evolutionary sense to have a pre-flight-capable wing for
> > making pretty, that later develops flight-worthiness, than a post-flight
> > flipper developing flight-worthiness does...
> >
> > >I have visions of those (I think) Capercailles(?) which leap up from the
> > ground and flash their wings in display....is that what you have in mind?

-- 
Flying Goat Graphics
http://www.flyinggoat.com
(Society of Vertebrate Paleontology member)
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