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In a message dated 95-12-03 13:26:21 EST, Robert.J.Meyerson@uwrf.edu (Rob
Meyerson) writes:

>How about this:  The theropod that evolved flight did so along a highly=
> irregular land surface (like a rocky shoreline).  Flight is used in
> of prey, where the theropod can simply glide over gullies, while it's prey=
> has to take the long way across (down and up).  Similar evolutionary=
> pressures as with the aboreal hypothesis, but with a cursorial origin.

Given that irregular land surfaces can be found everywhere, if the evolution
of flight were this easy from cursorial forms, there would certainly be more
kinds of flying vertebrates than just three (one extinct). Also, what would
cause the pursuing theropod to abandon a tried and true method of capturing
prey (by following it the long way across gullies) for gliding? That is, what
would compel the animal to take to the air in the first place? And finally,
there is nothing here about the evolution of powered flight, just gliding.