Meeting Abstract

P1.98  Tuesday, Jan. 4  Functional differentiation of the trailing and leading forelimbs during terrestrial and arboreal locomotion in the European red squirrel (Sciurus vulgaris, Rodentia). SCHMIDT, A.; Ohio University, Athens andre.schmidt-jena@gmx.de

During in-phase (asymmetrical) gaits, the footfalls of each pair of feet are unevenly spaced in time. Due to this asymmetry, a functional differentiation in kinetics and kinematics between the first limb (trailing limb) and second limb (leading limb) to touch the ground is apparent but has never been explored in depth. In order to determine the functional differences between trailing and leading limbs during terrestrial and arboreal locomotion, x-ray motion analysis and force measurements were taken in two European Red Squirrels (Sciurus vulgaris, Rodentia). The differences observed between trailing and leading limbs were only minimal during terrestrial locomotion, where both limbs fulfill two functions and go through a shock-absorbing phase followed by a generating phase. During arboreal locomotion squirrels used a compliant gait associated with a reduction in speed and in the substrate reaction forces, possibly due to the reduction of vertical oscillation of the center of mass. Limb flexion and lead intervals, on the other hand, increased. The increase in lead intervals significantly affects limb protraction and retraction, elbow yield, limb abduction and vertical displacement and the distances covered by the proximal pivot. Trailing limbs function exclusively as shock-absorbing elements. In contrast, a high level of stiffness characterizes leading limbs. As a result, trailing and leading limbs fulfill different functions. This functional differentiation indicates that squirrels `test´ the substrate for stability with their trailing forelimb, while the leading forelimb respond to or counteract swinging or snapping branches.