Final answer:
The term for an anatomical change in the leg allowing bipedalism is the 'valgus angle' of the femur. This, along with other skeletal adaptations like strengthened limb bones and aligned toes, enables efficient two-legged walking and running.
Step-by-step explanation:
Adaptations for Bipedalism: The term for an anatomical change in the leg enabling bipedalism is the formation of the valgus angle of the femur. This adaptation positions the knees and feet beneath the pelvis, allowing for efficient bipedal locomotion. In addition to the valgus angle, other important changes include the development of spinal curves for balancing the body weight on the hips, the evolution of an arched foot, and the alignment of the big toe alongside the other toes to effectively transmit weight during movement. These adaptations are critical for the stance leg to support the body while the step leg moves forward during walking or running. Moreover, the bones of the lower limb, including the femur, tibia, fibula, and the bones of the foot, are strengthened to support the body's weight and withstand the forces applied during locomotion. Joints, such as the hip and knee joints formed by the femur, play an essential role in facilitating movement and ensuring stability during bipedal movement.