Final answer:
The oldest evidence for human-like bipedalism comes from the Laetoli footprints discovered by Mary Leakey, attributed to Australopithecus afarensis around 3.5 MYA. Earlier evidence of bipedalism is also seen in Ardipithecus species dating back as far as 5.6 MYA. These fossils showcase the anatomical adaptations necessary for bipedal walking.
Step-by-step explanation:
The oldest evidence for human-like bipedalism is provided by the Laetoli footprints, discovered by Mary Leakey in the 1980s. These footprints, dating back about 3.5 million years ago (MYA), were created by Australopithecus afarensis, an early hominin species. Australopithecus afarensis is evidenced to have had a modern striding gait similar to that of humans today. Furthermore, species such as Ardipithecus show bipedal locomotion at even earlier dates, with A. ramidus and A. kadabba dating back to about 4.4 MYA and 5.6 MYA, respectively.
The discovery of these footprints and fossils has greatly informed our understanding of the evolutionary development of bipedalism, one of the defining characteristics of the hominin lineage. These early hominins exhibited anatomical changes conducive to bipedal walking, such as angled femurs, spinal curvature, and arched feet, which were necessary adaptations for the shift from quadrupedalism to bipedalism.