Final answer:
Mary and Louis Leakey's significant archaeological work in understanding early human ancestors in Africa primarily took place at Olduvai Gorge where they discovered hominin fossils, including Paranthropus boisei, and Laetoli where Mary Leakey found ancient footprints evidencing bipedalism.
Step-by-step explanation:
The work of Mary and Louis Leakey was pivotal in advancing our understanding of early human ancestors in Africa. They conducted significant paleoanthropological excavations in the Eastern Rift Valley at notable sites. The most famous of their excavations was at Olduvai Gorge, where they discovered important fossils such as Paranthropus boisei. Additionally, Mary Leakey's discovery of bipedal hominin footprints at Laetoli contributed invaluable evidence of early hominin bipedalism.