Answer:
small brain, large teeth, at least some bipedal ability
Step-by-step explanation:
Unlike chimpanzees, australopithecs did not walk on four legs: they were definitely bipedal. The brains of most known Australopithecus species were 35% smaller than Homo sapiens and a skull not significantly larger than a current chimpanzee.
As for size, these animals were small, generally not exceeding 1.2 m in height. The teeth and jaw were also different, much larger and heavier than those of humans.
In summary, we can say that australopithecians had: small brain, large teeth, at least some bipedal ability.