Mary Douglas Leakey, FBA (née Nicol, 6 February 1913 – 9 December 1996) was a British paleoanthropologist who discovered the first fossilised "Proconsul" skull, an extinct ape which is now believed to be ancestral to humans. She also discovered the robust "Zinjanthropus" skull at Olduvai Gorge in Tanzania, eastern Africa. For much of her career she worked with her husband, Louis Leakey, at Olduvai Gorge, where they uncovered fossils of ancient hominines and the earliest hominins, as well as the stone tools produced by the latter group. Mary Leakey developed a system for classifying the stone tools found at Olduvai. She discovered the Laetoli footprints, and at the Laetoli site she discovered hominin fossils that were more than 3.75 million years old.