HYDE, Martha L; West Texas A&M University: Bipedal Locomotion In Two Species of Kangaroo Mice in the Laboratory

Previous work on Great Basin Desert kangaroo mice (9-13 g), Microdipodops pallidus and M. megacephalus have been shown to move bipedally as their nearest relatives, the kangaroo rats. Neither species of kangaroo mouse show a sustained bipedal hop when filmed with light film under normal filming conditions using extra lighting. This observational study of bipedal locomotion in M. pallidus (N=4), and M. megacephalus (N=5) using videotape with an infrared camera (PC-5ex Microvideo Cam, Supercircuits, Austin, Texas) and Canon videocam at 23 fps in the laboratory, showed that both species can sustain a bipedal hop within a rectangular, enclosed, sand-paper lined arena (152 cm-l x 47 cm-h x 42 cm-d). A backdrop with gridlines marked off with glitter and reflective markers and a camera-facing wall of mosquito netting were used as boundaries for this arena. An assistant induced the animals to hop bipedally. Sometimes a piece of chicken was also placed at one side of the runway as further inducement. Results showed slight differences between the two species in stride length, angle of projection, jump height and velocity as well as preferences in bipedal and quadrupedal locomotion. Some differences can be explained by habitat differences for the two species as shown in sandiness and presence of gravel in the substrate, density and height of vegetation. More important may be differences between these species and kangaroo rats.