OH 24 (Olduvai Hominid № 24, nicknamed "Twiggy") is a fossilized skull of the species Homo habilis. It was discovered in Olduvai Gorge, Tanzania by Peter Nzube in 1968. The skull was found crushed almost flat and was therefore named after the famously skinny model of the time Twiggy. Estimated at about 1.8 mya (million years old), the cranium was found crushed flat and cemented together with a mass coating of limestone. Originally, there was very little interest placed on the discovery of the skull, but after much effort by scientist Ron Clarke, the skull was finally reconstructed and examined thoroughly.Despite this effort, there still is a good deal of distortion from the fossilization processes that took place. The small cranial capacity estimated at about 590-600 cc (cubic centimeters) is in part attributed to this cranial distortion. OH 24's face is described as being prognathic (projecting forward under the nose), as in other fossils from the Homo habilis family, but not quite to the extent of earlier Australopithecus species. Besides manifesting lesser prognathism than the australopithecines, OH 24 also portrays a larger cranial vault, indicating an expansion in brain size from its ancestor, and the reduction of facial prognathisim typical of the evolution of early Homo.
