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Re: bauplan convergence



Leaping about in trees with a symmetrical drag mechanism (feathers or
membranes) leads to gliding.  

However gliders don't flap.  Cats, squirrels, lemurs, monkeys, lizards,
snakes, and frogs don't flap either.

The pre-existing ability and BEHAVIOR of flapping, a symmetrical drag
mechanism, and (probable) leaping about in trees is far more likely to
lead to flight than simply a drag mechanism plus leaping.  

The combination would be rare enough to account for flight only arising
in vertebrates 3 times.

poo, even us humans can glide with the right equipment.  

-Betty Cunningham

Stanley Friesen wrote:
> At 11:18 PM 6/16/00 -0700, Rob Gay wrote:
> >The main problem I have with avian flight originating in trees, is that I
> >can't see a good reason for animals to be leaping from them, unless they
> >had a sort of death wish.
> 
> Why do ordinary squirrels, ordinary lemurs, monkeys, lizards and snakes
> leap from trees?
> 
> Whatever the reason, it is sufficiently compelling that many, if not most,
> arboreal and scansorial animals do it.  Ergo, it is likely that any extinct
> arboreal/scansorial animal would do so as well.
> 
> >flying cat. As far as I can tell, most cats climb down out of the trees
> >instead of taking a 20 foot vertical drop.
> >Peace,
> 
> Actually, cats are notorious for their "death-defying" leaps.  TRemember,
> they are said to always land on their feet.

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