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Re: cursorial flapping -Reply
In a message dated 95-12-03 11:12:11 EST, longrich@phoenix.Princeton.EDU
(Nicholas R. Longrich) writes:
> One preadapation towards flight that arboreality may cause is
>developing the arms and putting them in the right position. I don't know
>how constrained the movement of theropod arms are, but whenever I see
>squirrels, I notice how sprawled out the legs are when they run over the
>ground. When they get up in the trees, the arms spread wide to grip the
>trunk. This puts the arms and legs in a perfect setup to develop a
>glide-plane. One problem is that the motions employed are the opposite-
>squirrel arms produce most of their power pulling backwards, while birds
>produce their power an a forward, downward stroke. But what might develop
>these muscles would be clmibing forward down the tree, instead of up,
>and, once glide-plains are developed, the muscles to hold these in place.
>The problem of course remains the flapping.
Indeed, part of the impetus behind BCF is my personal observations (casual
and not scientific, but real-life nevertheless) of squirrels in trees and how
they use their forelimbs, then extrapolating their movements to small
archosaurs of similar habits. It also explains how "flying squirrels"