HINDLIMB KINEMATICS DURING TERRESTRIAL LOCOMOTION IN A SALAMANDER (DICAMPTODON TENEBROSUS)

A quantitative study of hindlimb kinematics during terrestrial locomot ion in a nonspecialized salamander was undertaken to allow comparisons with limb movements in other groups of tetrapods. Five Dicamptodon te nebrosus were videotaped at 200 fields s(-1) walking on a treadmill. C oordinates of marker points on the salamander's midline, pelvic girdle and left hindlimb were digitized through at least three strides at bo th a walk (0.77 SVL s(-1), where SVL is snout-vent length) and a trot (2.90 SVL s(-1)). Marker coordinates were used to compute kinematic va riables summarizing trunk flexion, pelvic girdle rotation, femoral pro traction/retraction and knee flexion/extension. The stride is characte rized by uninterrupted trunk and pelvic girdle oscillation, femoral re traction throughout stance phase, and knee flexion in early stance fol lowed by extension. Mean angular excursions are: trunk, 66 degrees; pe lvic girdle, 38.5 degrees; pelvic girdle-femur, 106 degrees; and knee, 65 degrees. The hindlimb and pelvic girdle also show a complicated pa ttern of lateral movement related to knee flexion/extension and period s of support by the contralateral hindlimb during the step cycle. Dica mptodon shares the following features of the hindlimb step cycle with other tetrapod taxa: rotation of the pelvic girdle through a 30-40 deg rees are, femoral retraction beginning simultaneously with and persist ing throughout stance phase, flexion of the knee in early stance, and extension of the knee in late stance.