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While these ancient footprints shed fresh light on our nearer ancestors, Anthropologist Elwyn Simons, director of Duke University's primate center, revealed new findings on more distant kin. Most scientists agree that both man and ape descended from a common ancestor, a beast called Dryopithecus (meaning tree ape), which appeared in Africa some 20 million years ago. But who, or what, preceded it? As far back as 1963, Simons, then at Yale, began uncovering in the wind-scoured Fayum desert region, southwest of Cairo, bones of a likely candidate: a small, fox-sized, tree-inhabiting primate, which he dubbed Aegyptopithecus (Egyptian Ape), that lived some 28 million to 30 million years ago. Returning there last fall, Simons and a colleague from the State University of New York at Stony Brook, John Fleagle, discovered the latest pieces in the jigsaw puzzle, four fragments of humeri, or upper-arm bones. Until now, it had been assumed that Aegyptopithecus swung through trees as modern monkeys do, but the humeri show that it was not a swinger or leaper, but simply walked on all fours from branch to branch.