Reappraisal of the taxonomic status of the cranium Stw 53 from the Plio/Pleistocene of Sterkfontein, in South Africa

Abstract

ABSTRACT. A fossil skull, Stw 53, from the Plio/Pleistocene of Sterkfontein, in South Africa, has been referred to Homo habilis LEAKEY, NAPIER, and TOBIAS, 1964. Reappraisal of its putative hominine affinity reveals a closer resemblance to Australopithecus africanus DART, 1925. The skull, as reconstructed, is too small for H. habilis; with no indication of brain expansion over A. africanus; has a facial angle outside the hominine range, but identical with that of A. africanus; and whose teeth are not elongated but display buccolingual expansion. Although it was found in the same strata (Member 5) as stone tools, there is no causal connection. It has been dated faunistically at 2-1.5 my BP, but due to an unconformity it is suggested that it could be older.

The mid-face of lower Pleistocene hominins and its bearing on the attribution of SK 847 and StW 53

“…Some multivariate analyses show a close association between SK 847 and StW 53 (Curnoe, 2002(Curnoe, , 2010Grine et al, 1993Grine et al, , 1996 but this resemblance is not borne out across the board. Our analyses reveal StW 53 is far more similar to A. africanus than it is to SK 847, corroborating the observations of others (Berger et al, 2010;Cartmill and Smith, 2009;Clarke, 2008;Ferguson, 1989;Kuman and Clarke, 2000). With respect to early Homo, a relatively strong resemblance exists between the maxilla of SK 847 and KNM-WT 15000, and between StW 53 and KNM-ER 1813, particularly for the sizes of maxillary features.…”

“…Similarities between SK 847 and StW 53 on the one hand, and differences between StW 53 and A. africanus on the other, are not universally supported (Cartmill and Smith, 2009;Ferguson, 1989;Schwartz and Tattersall, 2003;Thackeray et al, 2000;Wolpoff, 1996). Thackeray et al (2000) found StW 53 to be similar to Sts 5 and the difference between them to be comparable to what might be expected between two mammalian conspecifics.…”

“…A comparison of the semicircular canals of the bony labyrinth of the inner ear suggest that StW 53 differs substantially from other hominoids but that SK 847 is indistinguishable from modern Homo (Spoor et al, 1994). Given arguments about errors in a recent reconstruction of the cranium (Clarke, 2008), an examination of the maxilla of StW 53 is important for resolving whether this specimen should be included into the genus Australopithecus (Berger et al, 2010;Clarke, 2008;Ferguson, 1989;Kimbel et al, 1997;Kuman and Clarke, 2000;Wolpoff, 1996) or Homo (Curnoe, 2001(Curnoe, , 2002(Curnoe, , 2010Curnoe and Tobias, 2006;Grine et al, 1993Grine et al, , 1996Hughes and Tobias, 1977;Smith and Grine, 2008).…”

Variability of Australopithecus second maxillary molars from Sterkfontein Member 4

“…Initially allocated to Homo habilis (Hughes and Tobias, 1977;Howell, 1978;Tobias, 1978;Clarke, 1985a;Curnoe and Tobias, 2006), StW 53 was considered by Curnoe (2010) as belonging to a distinct early Homo species that he named Homo gautengensis, while others (Ferguson, 1989;Kuman and Clarke, 2000;Thackeray et al, 2000;Clarke, 2008Clarke, , 2013 claimed it should belong to Au. africanus.…”

The role of character displacement in the molarization of hominin mandibular premolars

“…Some southern African hominin fossils have been assigned to Homo, but they are not included in this analysis because either there is no consensus over their taxonomy, or because the evidence for geological age is weak. Some of these specimens, such as Stw 53 and SK 847, have been assigned to early Homo (Hughes and Tobias 1977;Howell 1978;Tobias 1978Tobias , 1991Corruccini 1980;Chamberlain 1987;Clarke 1990Clarke , 1994Grine et al 1993Grine et al , 1996, but they have also been linked with later Homo (Robinson 1960(Robinson , 1967Clarke 1977;Tobias 1978;Groves and Mazak 1975;Walker 1981;Dean and Wood 1982;Spoor et al 1994) or with non-Homo taxa (Mann 1970;Wolpoff 1970Wolpoff , 1971Krantz 1977;Wood and Abbott 1983;Wood and Uytterschaut 1987;Ferguson 1989;Kuman and Clarke 2000;Berger et al 2010). The allopatric population of Homo was restricted to individuals in areas with no known overlap with any non-Homo hominin.…”