What evidence suggests that Australopithecus was an erect biped?

What evidence suggests that Australopithecus was an erect biped? How did the loco motor pattern of Au. Afarensis differ from that of H. sapiens? Some paleoanthropologists consider Au. apheresis as an intermediate between the Miocene dental apes and the hominins. What are some of the apelike characteristics of the skeleton of Au. afarensis?