To make the case that the Olduvai Gorge habilis fossils belonged in Homo, Leakey, Tobias, and Napier had focused on the teeth and jaws, a bit more erectus-like than the more primitive Australopithecus africanus. They had partial skulls as well, and although the brain sizes were smaller than any erectus skull then known, they seemed a bit bigger than the small-brained africanus. With a partial hand skeleton and stone tools nearby, they had enough for the textbooks to enshrine it as ancestor: habilis begat erectus which begat sapiens.
But by the 1990s, anthropologists couldn’t ignore the small size of supposed habilis body fragments — especially the fragmented but clearly tiny OH 62 skeleton discovered by Tim White and Donald Johanson at Olduvai in 1986. Around the same time, Bernard Wood began to argue that the largest and most complete skull attributed to habilis, the KNM-ER 1470 skull from Koobi Fora, Kenya, should really belong to a different species entirely, Homo rudolfensis. In light of these changes, many scientists began to revisit the old idea that habilis might not be so different from Australopithecus after all.