OH 7

OH 7 ("Olduvai Hominid № 7") is the type specimen of Homo habilis. The fossils were discovered on November 4, 1960 in Olduvai Gorge, Tanzania, by Jonathan and Mary Leakey. OH 7, which is dated to approximately 1.75 million years, consists of fragmented parts of a lower mandible (which still holds thirteen teeth), an isolated maxillary molar, two parietal bones, and twenty-one finger, hand, and wrist bones. The parietal bones — a nearly complete left parietal and fragmented right parietal — were used to deduce the cranial capacity of the hominid, which was placed at 363 cc in account of the fact that the fossils belonged to a 12- or 13-year-old male. This was extrapolated by Phillip V. Tobias to 674 cc for the hominid’s full adult potential. However, other scientists have estimated the cranial capacity at 590 cc. to 710 cc

Louis Leakey, John Napier, and Phillip Tobias were among the first to extensively study the fossils. The Leakey team and others argued that, due expanded cranial capacity, gnathic reduction, relatively small post-canine teeth (compared to Paranthropus boisei) , Homo-like pattern of craniofacial development , and a precision gap in the hand fragments (which indicated the ability for tool use), set OH 7 apart as a transitional species between Australopithecus africanus and Homo erectus. In January 1964 the Leakey team announced the new species Homo habilis, igniting debate among the anthropology community which lasted through the 1970s. Many anthropologists noted the specimen was found in a region known to contain P. boisei fossils, and that the differences between the two were not enough to warrant a new species. Others believe OH 7 more closely resembles A. africanus.