Re: bauplan convergence

[Ronald Orenstein <ornstn@home.com>]

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
1825 Shady Creek Court
Mississauga, Ontario, Canada L5L 3W2          mailto:ornstn@home.com