Final answer:
Mary Leakey discovered Paranthropus boisei in 1959 during her extensive fossil search with her husband Louis Leakey in East Africa's Eastern Rift Valley.
Step-by-step explanation:
The individual who discovered Paranthropus boisei was Mary Leakey. This discovery happened during a comprehensive fossil search in East Africa by Mary Leakey and her husband, Louis Leakey, in 1959. Paranthropus boisei, also known as the hyper-robust hominin due to its distinctive skeletal features, was found in the Eastern Rift Valley which extends through Ethiopia, Kenya, and Tanzania. Paranthropus boisei was notable for its large jaws and skull structures adapted for powerful chewing. The couple's work in paleoanthropology echoes the importance of detailed field research in discovering human ancestry.