HIGHAM, T.E.*; JAYNE, B.C.; Univ. of Cincinnati; Univ. of Cincinnati: Locomotion of lizards on inclines and perches: Comparative three-dimensional hindlimb kinematics of an arboreal specialist (chameleon) and a terrestrial generalist

Arboreal animals often traverse three-dimensional networks of narrow perches with variable inclines, but the effects of both incline and narrow surfaces on the locomotor movement and function of limbs are poorly understood. Thus, we examined the three-dimensional hindlimb kinematics of Chamaeleo calyptratus moving on narrow (2.3 cm) perches and a flat treadmill with inclines of -30^�, 0^�, and 30^�. For a similar speed of locomotion on a flat treadmill, ten of 14 kinematic angles differed significantly between C. calyptratus and Dipsosaurus dorsalis (with a more generalized limb posture). Chameleons had unexpectedly large amounts of pelvic rotation, which exceeded values of D. dorsalis, especially on the level surface (57^� vs. 42^�). The angles of the knee at footfall of C. calyptratus commonly exceeded 120^�, whereas those of D. dorsalis rarely exceed 90^�. On the level surface, C. calyptratus also had greater values of long-axis femur rotation (92^� vs. 83^�) and femur protraction (-60^� vs. -45^�) than those of D. dorsalis. Unlike D. dorsalis, the knee of C. calyptratus was commonly above the hip at footfall. Few aspects of the kinematics of chameleons on treadmills and perches differed significantly, and inclines had more pervasive effects on the kinematics of D. dorsalis compared to C. calyptratus. Thus, the kinematics of C. calyptratus were relatively stereotyped compared to those of D. dorsalis, and certain effects of incline were taxon-specific rather than globally similar. Supported by NSF IBN 99-83003.