Richard J. Sherwood Department of Anthropology, University of Wisconsin, Madison, Wisconsin 53706, U.S.A. E-mail: rjsherwood@facstaff.wisc.edu Steven C. Ward Department of Anatomy, Northeastern Ohio Universities, College of Medicine, Rootstown, Ohio 44272, U.S.A. E-mail: scw@neoucom.edu Andrew Hill Department of Anthropology, Yale University, New Haven, Connecticut 06520, U.S.A. E-mail: andrew.hill@yale.edu Received 9 July 1997 Revision received 6 March 2000 and accepted 6 March 2000 Keywords: Chemeron temporal, Homo, temporal bone. The taxonomic status of the Chemeron temporal (KNM-BC 1) Temporal bone morphology, as part of the basicranium, is commonly used in systematic evaluation of early hominid fossils. When an isolated right temporal bone, KNM-BC 1 (the Chemeron temporal) was discovered in the Baringo Basin, Kenya, Tobias (1967a, Nature 215, 476–480), citing ambiguity of characters, hesitated to place the specimen generically, attributing the fossil only to Hominidae gen. et sp. indet. Since that discovery, the early hominid sample has grown considerably and comparisons with this expanded dataset led Hill et al. (1992a, Nature 355, 719–722) to revise the placement of KNM-BC 1 including it within the genus Homo. This revision was possible due to the increased number of hominid fossil specimens from the late Pliocene/early Pleistocene, most notably members of the genus Homo. A thorough investigation into the utility of the temporal bone in hominid systematics shows that many features, as currently used in the literature, demonstrate high levels of variation thus questioning their phyletic valence. It is shown, however, that the temporal bone still contains useful systematic information. A detailed anatomical description of KNM-BC 1 is provided and, when dis- cussed in the context of temporal bone features provided, affirms the conclusion of Hill et al. (1992a) and places the fossil within the genus Homo.  2002 Academic Press Journal of Human Evolution (2002) 42, 153–184 doi:10.1006/jhev.2000.0409 Available online at http://www.idealibrary.com on Introduction The Chemeron temporal bone (KNM-BC 1; Figure 1) was discovered in October 1965 by John Kimengich, then a field assistant to John Martyn who was investigating the region geologically as a member of the East African Geological Research Project (EAGRU). The specimen, a right with minor damage to the mastoid, petrous and squamous, was identified as hominid shortly afterwards by Jonathan Leakey. It was found at EAGRU site JM85 (now BPRP#2 in the Baringo Paleontological Research Project Catalog). The site was later excavated by Mary Leakey, but no further hominid material was unearthed. Information regard- ing the geological context and provenance of the fossil within the site was given by Martyn (1967; see also Leakey et al., 1969), and some further information is provided by Deino & Hill (2002). A detailed and docu- mented account of the circumstances of the specimen’s discovery and geological situ- ation is given in Hill (1999). The specimen was particularly interesting at the time as the first non-Homo sapiens hominid to be found in Kenya. KNM-BC 1 has had a varied taxonomic history. In the initial description Tobias (1967a) felt the available evidence too sparse and ambiguous to assign the speci- men at a rank below family level. Leakey (1973) later discussed the specimen. He mistakenly reports that Tobias assigned the bone to Australopithecus, but shows some prescience in suggesting that, ‘‘Although the fossil was located on the surface, there is no 0047–2484/02/010153+32$35.00/0  2002 Academic Press