Mary Leakey (6 February 1913–9 December 1996) was a British paleoanthropologist who discovered the first fossilized Proconsul skull, an extinct ape now believed to be ancestral to humans. She also discovered the robust Zinjanthropus skull at Olduvai Gorge. For much of her career she worked with her husband, Louis Leakey, in the Olduvai Gorge, in eastern Africa, uncovering the tools and fossils of ancient hominines. Leakey developed a system for classifying the stone tools found at Olduvai. She discovered the Laetoli footprints. It was here, at the Laetoli site, that she discovered Hominin fossils that were more than 3.75 million-years-old.