AP BIOLOGY

Detailed explanation-1: -bipedalism, a major type of locomotion, involving movement on two feet. The order Primates possesses some degree of bipedal ability. All primates sit upright. Many stand upright without supporting their body weight by their arms, and some, especially the apes, actually walk upright for short periods.

Detailed explanation-2: -Humans, birds and (occasionally) apes walk bipedally. Humans, birds, many lizards and (at their highest speeds) cockroaches run bipedally.

Detailed explanation-3: -Ardipithecus ramidus lived about 4.4 million years ago in Africa. It is the first hominin we are sure walked on two legs. Ardipithecus was what we call a facultative biped, which means it was capable of walking on two legs but only did it sometimes. We know this from Ardipithecus’ hip bones.

Detailed explanation-4: -About seven million years ago, our early ancestors climbed trees and walked on four legs when on the ground. By five million years ago, our ancestors had developed the ability to walk on two legs but their gait was quite different from our own and their skeletons retained some features that helped them climb trees.