Final answer:
The Laetoli footprints demonstrate that Australopithecus afarensis was bipedal with a gait similar to modern humans, but its anatomy suggests it also spent time in trees.
Step-by-step explanation:
The Laetoli footprints provide critical evidence that the species Australopithecus afarensis, which existed from 3.9 to 2.9 million years ago (MYA), adopted a bipedal mode of locomotion akin to modern humans. Discovered by Paleoanthropologist Mary Leakey in the 1980s, the 75-foot trail of footprints in East Africa's Laetoli site shows a modern striding gait of three bipedal hominins walking across wet volcanic ash around 3.5 MYA. These findings, coupled with the anatomical evidence such as a pelvis resembling that of modern humans, a more anterior position of the foramen magnum, and the angle of the femural head and neck suggest that A. afarensis was both bipedal and arboreal. The long and curved finger and toe bones, as well as longer arms, however, indicate they also spent significant time in trees.