Meeting Abstract
Giraffes (Giraffa camelopardalis) are ruminant artiodactyls whose large body mass combined with long, gracile limb and neck proportions render them highly derived in comparison to sister taxa. Neck and limb elongation is predicted to have functional consequences with respect to locomotion in giraffes. Previous studies have been confined to describing kinematics from a small number of trials, usually with single individuals. We have measured ground reaction forces and simultaneous 2D kinematics from three adult giraffes, from over 100 walking trials. Data were gathered over several days in an outdoor zoo enclosure. Giraffes were encouraged to walk over a forceplate array at their preferred speeds. We describe basic kinematic parameters (including stride length, stride frequency, duty factor and preferred speed), and relate these to peak vertical and horizontal forces. The three adults of similar size demonstrated a singlefoot in lateral sequence gait, using a preferred speed of 1.2m/s. At this velocity, the mean (of forelimb and hindlimb) duty factor was 0.67, peak forelimb vertical ground reaction force was 0.76x body weight, and peak hindlimb vertical force 0.4x body weight. Mean stride length was 2.3m, and mean stride frequency 0.5 Hz. Changes in walking speed were achieved both with an increase in stride length, and to a lesser extent an increase in stride frequency. The long neck of giraffes surely provides a high moment of inertia, which may in turn influence the acceleration and deceleration forces of the forelimb. We hypothesize that oscillations in neck angle are linked to the forelimbs’ horizontal forces, and find that the peak neck flexion coincides with peak braking force in early stance, but is disconnected from peak propulsive force.
