Some stock footage shots, as well as the mammoth and Megaloceros models, were recycled from Walking with Prehistoric Beasts (2001).
In Walking with Prehistoric Beasts (2001), the Australopithecus were portrayed via computer graphics and animatronic puppets because of their non-humanlike proportions. In this show, they are all actors wearing extensive makeup (minus the baby Australopithecus, which is of course a puppet). This method sacrificed anatomical accuracy for more expressive and diverse characters.