Fig. 3. Intervertebral movements of the `tailless' pika Ochotona rufescens (A) and the `long-tailed' gray short-tailed opossum Monodelphis domestica (B) after Fast-Fourier Transformation. The different presacral intervertebral joints (PS) are indicated by different colors. The footfall pattern of the hindlimbs is indicated by the ground contact duration (stance phase) on the top of each diagram. Note the different ranges of `pelvic movement' of the species.