Australopithecus Sediba Child's FossilRemarkably well preserved for a two-million-year-old fossil, this child's skull belongs to Australopithecus sediba, a previously unknown species of ape-like creature that may have been a direct ancestor of modern humans, according to a new study in Science.(Full story: "'Key' Human Ancestor Found: Fossils Link Apes, First Humans?")Scientists think this particular Australopithecus sediba fossil is from a male between 8 and 13 years old. The child's fossils were found in the remnants of a subterranean South African cave system alongside the fossil remains of an adult female in her 30s.

"It's the opinion of my colleagues and I that [A. sediba] may very well be the Rosetta stone that unlocks our understanding of the genus Homo," the biological group that includes humans, study leader Lee Berger, of the University of Witwatersrand in Johannesburg, said in a statement, referring to the artifact that helped decipher ancient Egyptian hieroglyphics.

A. sediba could help anthropologists understand, to a greater degree than any human-ancestor species discovered so far, the transition from late australopithecines—the apelike group of species that came before the first Homo species—to the first direct ancestors of humans, Berger added.(Also see "Oldest Skeleton of Human Ancestor Found.")—Ker Than

Photograph courtesy Brett Eloff and Lee Berger