The diagrams depict the skeletal structures of Australopithecus afarensis and Homo erectus
Overall, Australopithecus afarensis possessed traits, such as long forearms and small joints, suited to general walking and climbing trees, whereas Homo erectus exhibited features designed for upright walking and endurance running, including balanced head, larger joints and a stabilized foot arch.
Regarding upper body, Australopithecus afarensis had an unbalanced head, high and narrow shoulders, and wider chest in contrast to the balanced head, lower and wider shoulder girdle, and a narrower torso of Homo erectus. Moreover, the former possessed a short, wide waist with a long forearm while the latter featured a taller and narrower waist along with shorter arms.
Looking into the lower parts, Australopithecus afarensis had a long femoral neck, smaller articulations in hips, knees and ankles, and a short Achilles tendon. Its partial foot arch and long toes also indicate the concurrent evolving gait. Conversely, Homo erectus featured large joints, a lengthened Achilles tendon, an enlarged heel bone, short toes and a stabilized foot arch adapted for bipedal locomotion.