Fig. 1. Typical locomotory sequences for (A) P. parnellii, (B) D. rotundus and (C) D. youngi. Images are at 44 ms intervals. In those images for which only the hindlimbs are in contact with the left plate, the normal force for that plate is shown as a yellow arrow. The graph below each image shows the magnitude of the force on the left plate over the course of the image sequence. Open yellow circles indicate the timing of images with force vectors. Solid circles give the times of all other frames. Note that the magnitude of the force vector for both vampire species decreases gradually as the animal shifts its weight forward, but that the forces are highly variable for the poorly crawling bat, P. parnellii.