Final answer:
The most important evidence for bipedalism is the discovery of footprints made by Australopithecus afarensis. Changes in anatomy, such as the angling of the femur and evolution of the arch in the foot, also indicate bipedalism.
Step-by-step explanation:
The most important evidence for bipedalism is provided by the discovery of 75-foot trail of footprints in East Africa. These footprints, dating back to about 3.5 million years ago, were made by Australopithecus afarensis. Analysis of the footprints indicated a modern striding gait, indicating bipedalism. Other evidence includes changes in anatomy, such as the angling of the femur, the evolution of the arch in the foot, and realignment of the big toe. These anatomical changes facilitate successful bipedal locomotion.