Fig. 1From: Origin of the propatagium in non-avian dinosaursMusculoskeletal system of the avian left wing in ventral view. A, B, Propatagium (A) and forelimb muscles (B). C, D, Synchronous actions between the elbow and wrist joints, at an extension via the function of the musculus (m.) propatagialis (C) and at a flexion via the interlocking wing-folding system (D)Back to article page