Fig. 3. (A) Phase shift between the fluctuations in total kinetic energy and gravitational potential energy versus velocity. Phase shifts around 0° indicate that the two energies are in phase with one another and thus all steps analyzed exhibit spring mechanics. (B) Percentage recovery (measuring the efficiency of pendular mechanics) versus velocity. Low values indicate little to no pendular exchange of mechanical energy characteristic of spring mechanics. Note that neither variable changes significantly with speed, indicating that the opossums consistently use spring mechanics over the full range of speeds that they will perform sustained locomotion. Kinematic gaits are indicated by symbols: walking trots, open squares; non-aerial running trots, open circles; aerial running trots, filled circles.

Return to article