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re: bat/ptero wing fingers

tim williams wrote:

I wonder if a similar thing happened in the evolution of pterosaurs
(although in this case, it would just be one finger that was
super-elongated). In both proto-bats and proto-pterosaurs, the gliding
membrane would have to be extended along with the digits.

Just the opposite. Ptero membranes developed distally on a relatively
short finger four as yet another decorative membrane, then extended
medially to connect first with the elbow then the torso employing Jim
Cunningham's famous fuselage fillet to the upper thigh. The metacarpal
IV twist is indeed the twist in this story because in proto pterosaurs
the key was how to conceal this membrane when it got too big. Evidence
can be found in Sharovipteryx and Longisquama. And yes, of course, as
the finger got longer, so did the wing membrane. But it was not
analogous to the Colugo or the Rocket J. Squirrel situation.

David Peters
St. Louis