Archaeology African

ALT Illustration of OH 36 ulna fossil. Muia Mutala found this partial ulna during field survey as part of Mary Leakey’s team in 1970. Geologists have since determined that the Upper Bed II context of this fossil is roughly 1.15 million years old. Even with a centimeter or more broken off at the distal end, the preserved length of 266 mm is longer than the average human today. Its size suggests that the ulna might come from a tall individual of the human-sized Homo erectus. Yet its strongly curved shaft marks the bone as different from the ulna of the Turkana Boy skeleton. Another possibility is that the fossil represents Paranthropus boisei. Until scientists find an ulna of this species in association with identifiable skull or tooth fossils, we may not know which hominin the OH 36 ulna represents. Skeletal material curated at the National Museum and House of Culture, Dar es Salaam, Tanzania. Illustration by John Hawks CC-BY 4.0

ALT Illustration of KNM-ER 407 from Koobi Fora, Kenya. Mwongela Mwoka found this partial skull in 1969 in the fossil deposits of Koobi Fora. The individual lived between around 1.55 and 1.87 million years ago. The remains do not include any of the teeth or bones of the face, which has made this skull hard to interpret. Most scientists, looking at the relatively small brain size (around 430 ml) and inflated mastoid region behind the ear, think this was a small female individual of the large-toothed species, Paranthropus boisei. Still, the anatomy overlaps with other skulls attributed to Homo at the same place and time, like KNM-ER 1805. These similarities highlight the challenge of interpreting the initial differentiation of our genus from its close relatives. Original skeletal material curated at the Nairobi National Museum, Kenya. Illustration by John Hawks CC-BY 4.0