A comparative analysis of the hominin triquetrum (SKX 3498) from Swartkrans, South Africa

Tracy L Kivell

doi:10.4102/sajs.v107i5/6.515

Abstract

The SKX 3498 triquetrum from Member 2 at Swartkrans Cave, South Africa is the only hominin triquetrum uncovered (and published) thus far from the early Pleistocene hominin fossil record. Although SKX 3498 was found over two decades ago, its morphology has not been formally described or analysed, apart from the initial description. Furthermore, the taxonomic attribution of this fossil remains ambiguous as both Paranthropus and early Homo have been identified at Swartkrans. This analysis provides the first quantitative analysis of the SKX 3498 triquetrum, in comparison to those of extant hominids (humans and other great apes) and other fossil hominins. Although the initial description of the SKX 3498 triquetrum summarised the morphology as generally human-like, this analysis reveals that quantitatively it is often similar to the triquetra of all hominine taxa and not necessarily humans in particular. Shared hominid-like morphology between SKX 3498 and Neanderthals suggests that both may retain the symplesiomorphic hominin form, but that functional differences compared to modern humans may be subtle. Without knowledge of triquetrum morphology typical of earlier Pliocene hominins, the taxonomic affiliation of SKX 3498 remains unclear.

Highlights

Between 1979 and 1986 a complete, undistorted hominin right triquetrum (SKX 3498) was discovered from Member 2 at the Pleistocene site of Swartkrans Cave, South Africa (1.8 MYA – 1.0 MYA1)
Spearman rank correlation revealed that the four additional geometric means calculated from the subsets of variables available for fossil specimens (Table 2b) were significantly correlated with the geometric mean derived from all nine variables: (1) the Neanderthal specimens, (2) Dolní Věstonice 14, (3) Dolní Věstonice 3 and (4) Ar. ramidus
In the discriminant function analyses (DFA) based on the Neanderthal shape ratios, the first discriminant function distinguished Pongo from all other hominines because of its relatively broad triquetrum body and hamate facet and relatively short triquetrum body and long pisiform facet (Table 3a, Figure 7a)

Summary

Introduction

Between 1979 and 1986 a complete, undistorted hominin right triquetrum (SKX 3498) was discovered from Member 2 at the Pleistocene site of Swartkrans Cave, South Africa (1.8 MYA – 1.0 MYA1). The elliptical shape of the pisiform facet was described as being unique and unlike that of modern humans or chimpanzees.[2,3] Since this initial description, the SKX 3498 triquetrum has been rarely mentioned in the literature, most likely because it is the only early Pleistocene hominin triquetrum known (and published) and little comparative data exist.[4] because Swartkrans, and Member 2 are associated with both Paranthropus robustus and early Homo (Homo cf erectus5), the taxonomic affiliation of this carpal bone remains uncertain. This analysis provides the first quantitative analysis of this fossil in comparison to the triquetra of modern humans and other great apes (Figure 1) and to published data on hominin fossils (Ardipithecus ramidus, Homo neanderthalensis and archaic H. sapiens), with the aim of clarifying its functional and taxonomic interpretation

Methods

Results

Discussion

Conclusion