Three-dimensional molar enamel distribution and thickness in Australopithecus and Paranthropus

Thick molar enamel is among the few diagnostic characters of hominins which are measurable in fossil specimens. Despite a long history of study and characterization of Paranthropus molars as relatively ‘hyper-thick’, only a few tooth fragments and controlled planes of section (designed to be proxies of whole-crown thickness) have been measured. Here, we measure molar enamel thickness in Australopithecus africanus and Paranthropus robustus using accurate microtomographic methods, recording the whole-crown distribution of enamel. Both taxa have relatively thick enamel, but are thinner than previously characterized based on two-dimensional measurements. Three-dimensional measurements show that P. robustus enamel is not hyper-thick, and A. africanus enamel is relatively thinner than that of recent humans. Interspecific differences in the whole-crown distribution of enamel thickness influence cross-sectional measurements such that enamel thickness is exaggerated in two-dimensional sections of A. africanus and P. robustus molars. As such, two-dimensional enamel thickness measurements in australopiths are not reliable proxies for the three-dimensional data they are meant to represent. The three-dimensional distribution of enamel thickness shows different patterns among species, and is more useful for the interpretation of functional adaptations than single summary measures of enamel thickness

Blombos Cave, Southern Cape, South Africa: Preliminary Report on the 1992–1999 Excavations of the Middle Stone Age Levels

The Later- and Middle Stone Age levels at Blombos Cave (BBC) were excavated over four field seasons between 1992 and 1999. Here we report on the results from the Middle Stone Age (MSA) levels. The taphonomy and depositional history of the MSA levels is complex due to faulting, folding and spalling. Careful observations during excavation have assisted in understanding some of these taphonomic and site formation processes; microstratigraphic analysis, currently in progress, will add to this information. The uppermost MSA level, the Still Bay phase, contains high densities of bifacial points, the fossile directeur of the Still Bay Industry. Placing the Still Bay within the MSA culture sequence has been problematic in the past because Still Bay assemblages are rarely found in situ and previous excavations were inadequately recorded. However with the regional data discussed in the text, the Still Bay can be securely placed before the Howiesons Poort dated at 65–70 ka. Flaked stone makes up the greatest proportion of all artefacts with the highest incidence of retouch and use of fine grained, non-local materials found in the Still Bay levels. The ochre assemblage is remarkable for the mass of material compared to other MSA sites. Finds uncommon in an MSA context are two pieces of ochre from the Still Bay phase engraved with a geometric design; a fragment of deliberately engraved bone; also, 28 shaped and polished bone tools recovered mainly from a phase just below the Still Bay. Blombos Cave is the first site where well preserved faunal remains have been recovered in association with the Still Bay allowing for unique insights into human subsistence behaviour and palaeoenvironmental reconstruction. Large fish bones, marine shells, seals and dolphins attest to extensive exploitation of aquatic resources and a wide range of terrestrial animals were hunted and gathered. The few human teeth recovered are heavily worn and damaged thus the issue of morphological modernity cannot be addressed. The BBC findings are a useful ad