On the morning of 17 July 1959, Louis felt ill at Olduvai and stayed at camp while Mary went out to the field. At some point she noticed a piece of bone that "seemed to be part of a skull" with a "hominid" look". After dusting the topsoil away, she found "two large teeth set in the curve of a jaw", and she drove back to camp exclaiming "I've got him!" Active excavation began the following day and a partial cranium was unearthed within a few weeks, though it had to be reconstructed from fragments scattered in the scree. After examining the cranium, Louis Leakey concluded it was of a species ancestral to humans, the australopithecines.