The new specimens have "a really distinct profile" and thus they are "something very different," said Meave Leakey, describing the study published online Wednesday in Nature.

What these new bones did match was an old fossil that Meave and her husband Richard helped find in 1972 that was baffling.

White said it's similar to someone looking at the jaw of a female gymnast in the Olympics, the jaw of a male shot-putter, ignoring the faces in the crowd and deciding the shot-putter and gymnast have to be a different species.

Eric Delson, a paleoanthropology professor at Lehman College in New York, said he buys the Leakeys' study, but added: "There's no question that it's not definite." He said it won't convince doubters until fossils of both sexes of both non- erectus species are found. Explore further: Kenya's human fossils disturb church More information: Meave G.

Two likely possibilities are Homo rudolfensis —which is where 1470 and its kin seem to belong — and Homo habilis, where the other non-erectus belong, Anton said.

The team said the new fossils mean scientists can reclassify those categorized as non-erectus species and confirm the earlier but disputed Leakey claim.

Still, he said, East Africa nearly 2 million years ago "was quite a crowded place." And making matters somewhat more confusing, the Leakeys and Spoor refused to give names to the two non-erectus species or attach them to some of the other Homo species names that are in scientific literature but still disputed.

That's because of confusion about what species belongs where, Anton said.

So that would make two species — erectus and the one represented by 1470. The Leakey scientific team contends that other fossils of old hominids — not those cited in their new study — don't seem to match either erectus or 1470.

They argue that the other fossils seem to have smaller heads and not just because they are female.

And much of it stems from a controversial discovery that the Leakeys made 40 years ago.

In their new findings, the Leakey team says that none of their newest fossil discoveries match erectus, so they had to be from another flat-faced relatively large species with big teeth.

The KNM-ER 1470 cranium, discovered in 1972, combined with the new lower jaw KNM-ER 60000; both are thought to belong to the same species.