The world's oldest known child has been discovered in East Africa in an area known appropriately as the Cradle of Humanity.  The 3.3-million-year-old fossilized toddler was uncovered in north Ethiopia's badlands along the Great Rift Valley (map of Ethiopia). The skeleton, belonging to the primitive human species Australopithecus afarensis, is remarkable for its age and completeness, even for a region spectacularly rich in fossils of our ancient ancestors, experts say.  The new find may even trump the superstar fossil of the same species: "Lucy," a 3.2-million-year-old adult female discovered nearby in 1974 that reshaped theories of human evolution. (Related: "Fossil Find Is Missing Link in Human Evolution, Scientists Say" [April 2006].) .