pterosauria arm folding

[Nick Longrich <longrich@phoenix.Princeton.EDU>]

Anybody else notice (e.g. Padian's article on functional analysis of
flying and walking in pterosaurs) that pterosaurs have the exact same #@%^
kind of articulation for the radius and ulna as birds, or so it seems-
i.e. the articulations on the distal end of the humerus seem to have the
effect of pushing forward the radius relative to the humerus. Would this
have had the same effect as is seen in birds of folding (presumably to a
lesser degree, however) the wrist automatically when the arm is closed? 
Also, does anyone know anything about rhamphorhynch bipedalism? Is there
any trackway evidence of this? Anatomical evidence (trackways pretty
thoroughly demolish the idea that pterodactyloids weren't quadrupedal it
would appear)?