That's >exactly< my point. Feathered wings evolved just once. If feathered or
feathery or hairy forelimbs conferred any kind of real advantage on a
ground-dwelling cursorial vertebrate, we would see more such animals than
just birds.
Except that birds are, other than ourselves, about the only cursorial
bipeds we've got (kangaroos aren't really cursorial, and I'm not sure that
things like frilled lizards, which are only occasionally bipedal, fit here
either). If there were several other independently-evolved cursorial biped
lines for comparison, your idea (which I am not really disagreeing with)
would be more easily testable.
--
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