Carnivore activity at Klasies River Mouth: a response to Binford

Environmental and behavioural factors contributed to variability in the relative abundance of Raphicerus (grysbok/steenbok) represented in Late Pleistocene and Holocene deposits at the complex of caves at Klasies River Mouth and at Nelson Bay Cave in the southern Cape Province, South Africa. Binford has used the relative abundance of Raphicerus in an index assumed to measure the degree of hunting by Middle Stone Age hominids. However, the occurrence of relatively high numbers of Raphicerus with leopards and baboons in some layers is likely to have been associated, at least in part, with leopard activity, particularly at times when relatively large ungulates were not common in the palaeoenvironment and when the cave sites were not frequently occupied by hominids with control over fire. Binford's indices are re-assessed in the light of other indices which are designed to identify assemblages that have a relatively high probability of having been accumulated by leopards and/or other carnivores

The use of Z-scores to facilitate morphometric comparisons between African Plio-Pleistocene hominin fossils: An example of method

South Africa and East Africa each have a rich palaeoanthropological heritage, but the taxonomy of fossil hominins from these regions is controversial. In this study, two morphometric methods related to the quantification of variability in morphology have been applied to pairwise comparisons of linear measurements of hominoid crania and mandibles. The log-transformed standard error of the m-coefficient (‘log sem’) is calculated from linear regressions. Like Procrustes Distances (PD), log sem statistics can serve to quantify variation in the shape of a cranium or mandible in the context of a constellation of landmarks. In this study, PD and log sem statistics are integrated and standardised using Z-scores, and applied probabilistically to Plio-Pleistocene hominins. As a test case, OH 7 and OH 24 as reference specimens of Homo habilis are compared to fossils representing other taxa. There is a wide spectrum of variation in Z-scores for specimens attributed to early Homo dated within the period between circa 1.8 Ma and 2 Ma. In terms of morphometric variation predating 1.8 Ma, Z-scores (Z<2) for Australopithecus afarensis, A. africanus and Homo habilis display a small range of variability. This study serves as a demonstration of a method whereby log sem and PD can be used together to facilitate an objective assessment of morphological variability, applicable in palaeontological contexts. Significance:• Using a probabilistic approach, two morphometric methods are integrated to quantify morphological variability in Plio-Pleistocene African hominin mandibles and crania.• Two Tanzanian specimens of Homo habilis (the OH 7 mandible of the holotype specimen, and the OH 24 skull) can be used as reference material for morphometric comparisons with other fossils (mandibles or crania) attributed to Australopithecus africanus, A. afarensis, H. erectus and H. rudolfensis.• The results of these comparisons are expressed as standardised probabilistic Z-scores such that these statistics for skulls and mandibles can be expressed on a common scale

Variability in shape of the dental arcade of Homo sapiens in Late Pleistocene and modern samples from southern Africa

Mandibles are among the most common skeletal elements of Late Pleistocene specimens of Homo sapiens from southern African sites (notably Klasies River Mouth and Border Cave). For this reason mandibles have been selected for study to compare with samples drawn from modem populations (including South African negroes, Khoisanoid "Bushmen" and caucasoids). An analysis of shape of the dental arcade, based on the spatial distribution of molars, premolars and canines, indicates that several of the Late Pleistocene samples (including KRM 41815) are outside the range of variation found in modem African and caucasoid populations, and in this respect, cannot be described as "anatomically modem", sensu strictu. There appears to be a trend in the process of modernisation, from very flared dental arcades (notably in the case of the Kabwe skull, representing "archaic" H. sapiens), through moderately flared arcades (as found in Late Pleistocene "nearly modem" samples) towards a less flared condition which is found in modern Africans and caucasoids.Foundation for Research Developmen

Rainfall seasonality captured in micromammalian fauna in Late Quaternary contexts, South Africa

There exists ongoing debate regarding shifts in the latitudinal extent of the southern African winter-rainfall zone throughout the late Quaternary. Fossil proxies which can be related directly to rainfall seasonality have the potential to assist in quantifying these shifts. Relationships between mean monthly temperature and mean monthly rainfall in modern environments are quantified to generate a seasonality index associated with summer- or winter-rainfall. These seasonality indices can in turn be related to percentage occurrences reflecting relative abundances of rodent taxa represented in areas within southern Africa. Such data are used together to obtain an equation from which an index of seasonality in rainfall can be calculated, based on relative abundances of rodents in the modern landscape. The equation is applied to rodents represented in a Late Quaternary faunal sequence at Boomplaas Cave in the south-eastern part of the Western Cape Province. Results confirm that this region experienced a predominantly winter-rainfall regime during the Last Glacial Maximum (LGM), though the amount of rain may have been relatively low for the coldest episodes circa 20,000 cal. yr BP in the Boomplaas palaeo-environments.National Research Foundation, Andrew Mellon Foundatio

An experimental investigation into the origin of incised lines on a 4000-year-old engraving from Wonderwerk Cave, Northern Cape Province

An experimental investigation into the origin of incised lines on a 4000-year-old engraving from Wonderwerk Cave, Northern Cape Provinc

3D automated quantification of asymmetries on fossil endocasts

International audienceOver the last 15 years computed tomography (CT) has become a common way to obtain high resolution three-dimensional images of cranial endocast of hominids. Among the different features that can be seen on such endocasts, of key interest are their shape asymmetries. In particular, protrusions of the frontal and occipital lobes, as well as differences in their width, have been typically observed in modern humans' brains. These have been often hypothesized to be linked to functional specialization, and especially language and handedness. The imprints of these protrusions on the inner surface of the skull are called the petalia. There is a lack of automated, reproducible and objective methods to quantify these protrusions and to assess (for instance) whether they are present in species other than Homo sapiens. We propose a new method for the automated quantification of 3D endocranial shape asymmetries. We mathematically define the symmetry plane of the endocast as the 3D plane which best superposes the "right" and "left" sides of the endocranial surface. Then, we compute a 3D pointwise deformation field between the two sides of the endocast, allowing to match homologous points, and to assess their relative spatial position. The analysis of this 3D deformation field allows quantifying the shape asymmetries everywhere on the endocast. We illustrate our method on the endocast of Sts 5 (Mrs. Ples, Australopithecus africanus) whose very high resolution CT scan has been segmented using ITK-SNAP. The results suggest an opposite shape asymmetry in the fronto-temporal and occipital regions

Premolar root and canal variation in South African Plio-Pleistocene specimens attributed to Australopithecus africanus and Paranthropus robustus

South African hominin fossils attributed to Australopithecus africanus derive from the cave sites of Makapansgat, Sterkfontein, and Taung, from deposits dated between about 2 and 3 million years ago (Ma), while Paranthropus robustus is known from Drimolen, Kromdraai, and Swartkrans, from deposits dated between about 1 and 2 Ma. Although variation in the premolar root complex has informed taxonomic and phylogenetic hypotheses for these fossil hominin species, traditionally there has been a focus on external root form, number, and position. In this study, we use microtomography to undertake the first comprehensive study of maxillary and mandibular premolar root and canal variation in Australopithecus africanus and Paranthropus robustus (n = 166 teeth) within and between the species. We also test for correlations between premolar size and root morphology as predicted under the ‘size/number continuum’ (SNC) model, which correlates increasing root number with tooth size. Our results demonstrate previously undocumented variation in these two fossil hominin species and highlight taxonomic differences in the presence and frequency of particular root types, qualitative root traits, and tooth size (measured as cervix cross-sectional area). Patterns of tooth size and canal/root number are broadly consistent with the SNC model, however statistically significant support is limited. The implications for hominin taxonomy in light of the increased variation in root morphology documented in this study are discussed