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Re: bauplan convergence



At 11:18 PM 16/06/2000 -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. Without some form of control mechanism already in place, jumping out of the trees would seem to be detrimental to the population. And, even if some small therapods did spend time in trees, why is it assumed that they must develop flight. Felines have been around for millions of years, and I don't believe there has ever been a flying cat. As far as I can tell, most cats climb down out of the trees instead of taking a 20 foot vertical drop.

True, but tree kangaroos do just that - when threatened, they leap out of trees to the ground, sometimes from as high as 80 feet up, and seem to be able to do so without injury.


Besides, you are assuming that leaping from a tree can only lead to a fall to the ground. Of course, though, many animals are quite good at leaping from limb to limb within a tree, or from tree to tree (sometimes covering quite prodigous distances - eg sifakas). besides, it is hard to explain the evolution of gliding animals (as opposed to flying ones) any other way than as a series of steps from an arboreal leaping ancestor.
--
Ronald I. Orenstein Phone: (905) 820-7886
International Wildlife Coalition Fax/Modem: (905) 569-0116
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