Fossils of the extinct hominid known as Australopithecus sediba were accidentally discovered by the 9-year-old son of a scientist in the remains of a cave in South Africa in 2008, findings detailed by researchers last year. The fossils' mix of human and primitive traits found in the brains, hips, feet and hands make a strong case for it being the immediate ancestor to the human lineage, scientists report in the Sept. 9, 2011, issue of the journal Science.

The fossils included remains of a male juvenile (whose cranium is shown here) along with a female of the same species, who was likely in her 20s or 30s.