Final answer:
Bipedal movement evidence from the early Pliocene was found in Laetoli in East Africa. Mary Leakey's discovery of footprints provides insight into Australopithecus afarensis's locomotion, complementing other skeletal finds like those of Homo erectus that show adaptations conducive to bipedalism.
Step-by-step explanation:
Evidence of bipedal movement in the early Pliocene was found at the site of Laetoli in East Africa. Renowned paleoanthropologist Mary Leakey discovered a 75-foot trail of footprints that date back to about 3.5 million years ago, providing significant insight into the bipedal activities of early hominins, likely Australopithecus afarensis. These findings, along with the discovery of Ardipithecus ramidus in Ethiopia, highlight the evolutionary transition to bipedalism. Additional evidence supporting this transition to a bipedal lifestyle includes skeletal features such as a broader pelvis, longer legs, and arched feet found in early Homo species, like Homo erectus. However, it’s noteworthy that the adaptation to bipedalism didn't occur overnight, as some species displayed characteristics indicative of both bipedal movement and quadrupedal tree climbing abilities.