Paranthropus boisei mandible with its third molar (wisdom tooth) compared to a modern human mandible for size. "What is even more remarkable, is that these creatures were probably on average smaller than modern humans," says Grine.
Paranthropus boisei male skull from Olduvai Gorge (found by Mary Leakey in 1959). It shows the large crest on the top of the skull for the attachment of chewing muscles, etc.