From p. 48 of P. V. Tobias, Dart, Taung, and the Missing Link, Witwatersrand University Press, Johannesburg:
All fossil hominid discoveries up to 1925 had bearings on the evolution of established and unequivocal hominids; they had illustrated teh changes that had occurred along the way from incontrovertible earlier hominids (like Homo erectus of Java) to later hominids (like Neandertal and Cro-Magnon men). Australopithecus imported an entirely new dimension into the picture: it opened a window, not on to the evolution of established hominids, but on to human emergence -- the very roots of the family of hominids from non-hominid predecessors. It posed such questions as these: What are the features that distinguish hominids from other primate families? Which of the hallmarks of mankind were the first to appear and when did they arise? How were the different traits that characterize the human family related to one another? -- such traits as uprightness and bipedal locomotion, reduced canines, brain enlargement and structural re-arrangement, the human grasping and manipulating hand, human communication, human material culture including tool-making activities?
These were the kinds of questions which Dart's discovery and what he made of it compelled upon the world of science. Countless new areas of investigation were opened up -- even if the motivation was the felt need to repudiate Dart's claims! Dart's plunge into ancestral waters took the twentieth century to the very fountainhead where one could plumb the depths of human genesis.