Analysis of Posture and Gait Selection During Locomotion in the Striped Skunk (Mephitis mephitis)

Abstract

The pelvic and hindlimb posture and the gaits of Mephitis mephitis are described using cinematography (to 64 f.p.s.) and cineradiography (to 200 f.p.s.) of captive adult animals. M. mephitis preferentially selects a symmetrical, single-foot gait within the lateral sequence, which apparently provides maximum stability and, on the basis of comparative studies (Hilde-brand, 1976), is primitive. At speeds faster than the walk, the striped skunk seldom selects the trot; rather, it moves directly into a slow transverse gallop with little or no gathered suspension phase. This asymmetrical gait maximizes stability and is considered primitive. Several aspects of hindlimb posture of M. mephitis during walking reflect the pattern thought to be primitive for mammals (Jenkins, 1971; Jenkins and Camazine, 1977). In contrast to patterns of the more specialized carnivores, these aspects include: 1) upon contact of a foot the long axis of the femur intersects the sagittal plane at a relatively large angle (25° to 40°); 2) relatively greater adduction of the femur occurs just after foot contact (E2) followed by abduction in the late stance phase (E3) of the step cycle; and 3) the pelvis in E3 experiences a relatively greater contralateral shift. These features confer a wide and stable stance. Unlike those mammals thought to be primitive, however, M. mephitis positions its femur such that the distal end is always below the level of the acetabulum. Either we have misinterpreted the primitive condition in this regard, or the depression of the entire femur relative to the acetabulum was an adaptation among carnivores and related to an ambulatory way of life. The evidence leads us to conclude that in its gait selection and posture, M. mephitis represents the primitive condition for the Order Carnivora.