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3D reconstruction from CT scans of a 2.5 million year old australopithecine skull from Sterkfontein, South Africa. The top row is the 3D reconstruction of the original skull and the bottom row is the same skull with "missing" portions reconstructed.

G. C. Conroy, G. W. Weber, H. Seidler, P. V. Tobias, A. Kane, B. Brunsden (1998) Endocranial Capacity in an Early Hominid Cranium from Sterkfontein, South Africa. Science 12 June 1998. ABSTRACT In 1989 a large hominid cranium, Stw 505, was recovered in situ from Member 4, Sterkfontein. The specimen preserves much of the face and left side of a large adult male cranium and is the most complete hominid cranium recovered from Sterkfontein since the discovery of "Mrs. Ples" (Sts 5) just over 50 years ago. Although the skull has not been formally described, it has been figured in the literature as an example of A. africanus and is widely (but anecdotally) reported to have an endocranial capacity in excess of 600cc (Johanson and Edgar, 1996). If true, such brain size would be remarkable in any early hominid dated to approximately 2.8-2.5 mya, especially since it would exceed other A. africanus endocranial values by over 100cc and would approximate or even exceed the endocranial values of several early Homo specimens from both Olduvai and Koobi Fora nearly 500,000 -1,000,000 years younger in age (e.g., OH 16, OH 24, KNM-ER 1805, KNM-ER 1813). In order to evaluate the endocranial capacity of this remarkable, though incomplete, specimen, we first produced a computer generated (volume rendered) image of the complete skull (assuming bilateral symmetry) from CT data using the program ANALYZE. From these data the enclosed endocranial space could also be rendered as a separate 3D object and its volume calculated directly. These analyses, combined with direct water displacement tests using a detailed cast and stereolithographic model indicate that the true endocranial capacity is far less than the reported 600+ cc, and is more probably between about 500-530cc (allowing for some plastic deformation of the cranial vault). The latter value exceeds the largest value for 6 A. africanus crania so far determined or estimated, namely that of Sterkfontein hominid 5 ("Mrs. Ples") with a capacity of 485 cc. Glenn C. Conroy, Ph.D. Professor, Dept. of Anatomy & Neurobiology (Medical School) and Anthropology (College of Arts & Sciences) HOME PAGE