Jaime and Patrick have, unfortunately, put the cart before the horse.
Step back a few million generations.
Once the carpals bend (rotate), then you have the basis for a wing, not
before, hence the question. Case in point: Colugo.
David Peters
St. Louis
PS.
Jaime Headden wrote:
In regards to the squeeze he wrote about, the extant mammalian "sacrum"
is
not homologous to the ancestral amniote sacrum. As for frogs, they
ancestrally
posses a single sacral vertebra and the identity of this vertebra is
apparent
even in juveniles and fossils. The fused element of the urostyle is a
case of
fusion of proximal caudals, as is apparent when observing the ontogeny
of
Urodela, to the sacral to anchor the hip muscles, not the presence of a
fused
sacrum itself (hence the term urostyle, from _uro_ "caudal" + _style_
"rod").>>>
Try [functional] analog, Jaime. Not homolog.