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In a message dated 95-12-07 16:20:42 EST, ornstn@inforamp.net (Ronald
Orenstein) writes:

>OR: (assuming for argument's sake that we are dealing with an arboreal form)
>- the retroverted hallux would be a useful climbing and perching adaptation
>for an arboreal biped, freeing the forearms for use in grasping prey.  In
>fact this argument would provide an immediate benefit for such an adaptation
>- to me a more likely scenario than some promise of future flight.  If this
>is correct (and I submit it is at least plausible) then the retroverted
>hallux would be a benefit to nonvolant arboreal bipeds that could have
>included dromaeosaur ancestors.  As pointed out earlier, though, the
>retroverted hallux may also have beeen evolved in terrestrial predators to
>allow the foot to be used to grasp prey.

That's just what I gave as the _proximate_ cause of the development of the
retro-hallux. The benefits for flight were exapted later.

It's tough for me to imagine that the retro-hallux evolved in a biped _for
the purpose of grasping prey_. (It would make walking difficult, with a piece
of meat stuck to your foot.) It may, however, have been co-opted for a
ripping and tearing function--still tricky, since the average large theropod
with its stiff back and upwardly inclined neck would have a tough time
reaching between its hind legs for the morsels, but perhaps possible.