Alf G. Latham

A Multi-Disciplinary Perspective on the Age of Australopithecus in Southern Africa

This paper presents a review of, and new data concerning, the age of Australopithecus in southern Africa. Current dating suggests that Makapansgat Limeworks is the oldest hominin deposit in southern Africa, with Australopithecus africanus dating to between 3.0 and 2.6 Ma. The Taung Child A. africanus fossil from Taung is most likely penecontemporary with the Makapansgat material between 3.0 and 2.6 Ma. A. africanus from Sterkfontein Member 4 is estimated to date to between 2.6 and 2.0 Ma, with the Sts 5 specimen dating to around 2.0 Ma. The A. africanus deposits from Gladysvale are most likely contemporaneous with the Sterkfontein group with an age between 2.4 and 2.0 Ma. The potential second species of Australopithecus, StW 573 from the Silberberg Grotto at Sterkfontein, is most likely dated to between 2.6 and 2.2 Ma. As such, StW 573 is contemporary with A. africanus fossils from Member 4 and suggest that two contemporary Australopithecus species occurred at Sterkfontein between ~2.6 and 2.0 Ma. Based on the presence of Equus the A. africanus fossils from Jacovec Cavern also likely date to <2.4 Ma. The new Australopithecus sediba-bearing deposits of Malapa date to 1.98 Ma and suggests that three different species of Australopithecus occur in South Africa between 2.3 and 1.9 Ma. Given these dates, A. africanus represents the oldest southern African hominin species being found in two temporally distinct groups of sites, Makapansgat/Taung and Sterkfontein/Gladysvale, and A. sediba is the youngest species at ~1.98 Ma. However, if StW 53 is also Australopithecus, as some have suggested, then this genus survives to younger than 1.8 Ma in South Africa. Australopithecus thus lasted for a significant period of time in southern Africa after the genus is last seen in eastern Africa (Australopithecus garhi at ~2.5 Ma). This new dating indicates that the South African Australopithecus fossils are younger than previously suggested and are contemporary with the earliest suggested representatives of Homo (~2.3 Ma) and Paranthropus (2.7–2.5 Ma) in eastern Africa.

The Makapansgat australopithecine site from a speleological perspective

Abstract Remains of Australopithecus africanus from the Limeworks Cave, Makapansgat, South Africa, are believed to belong mainly to a metre-thick, bone-rich, speleothem layer. The flowstone is one stratum among a sequence of speleothems, muds, silts, sands and fine and coarse breccias, the study of which has evoked some disagreement. The limeworkers’ excavations revealed some stratigraphic relationships but they have obscured others. Partly because of this, controversy surrounds the supposition about whether there are separated depositional basins within the overall site and, if so, whether strata can be securely correlated. This is important because a reconstruction of an overall stratigraphic sequence was used as a basis for a magnetostratigraphic reversal record and by which the site has been tentatively dated. There is qualification and disagreement about the origin of the various flowstones and the actual depositional environment of the muds and silts. Evidence is presented which rules out some previous interpretations. From the point of view of the Australopithecine fossils themselves, it can be said that the calcite matrix in which they were provenanced was a low-energy environment and that the dense bone accumulation of this layer almost certainly did not arise by the action of floods, as previously supposed. The most likely main cause of the dense accumulation was hyena denning activity. It is clear that further work is needed to see how a reliable overall sequence can be established and that closer sampling is required for magnetostratigraphy.

Re-examination of the lower stratigraphy in the classic section, limeworks site, Makapansgat, South Africa

At the end of Member 2 times, remnant mammillary-form stalactites in the roof and wall contacts show that an irregular wedge-shaped space existed from the Classic Section out to the Cone area. It was into this space that hyenas and other denning animals were able to gain access from an as yet unfilled Cone area. During the mining operations of the 1920’s, Eitzman (1958) recollects entering an impressive bone breccia resembling a charnel house. We suggest that it is most probable that the Grey Breccia corresponds to his main breccia as only the area on top of Member 2, between the dolomite walls, roof and stalagmite boss has the required volume. It also lies at the end of an incline first dug by the miners, (still in existence), and at the end of which he was able to note some of the deposits. The bone breccias at the same level at the back of the Cone suggest that other dens were created at about this time.As the roof continued to retreat upslope and more material was washed in or fell in from the surface so more sediment was winnowed into the back of the Cone. At some stage this allowed prey animals to enter the Cone area and gain access between the speleothem barrier to the area of the Classic Section. As most Australopithecine fragments came from this breccia, it seems likely that, as with Swartkrans, the hominid fragments are the result of predation. Then as sediments continued to wash into the Cone area, the Classic Section and the back of the Cone became inaccessible for denning purposes.Large speleothem remnants embedded in sediment starting part-way up the Cone shows that a roof continued to exist in this area for some time. In fact, even today, although bits of speleothems can be found in the eroded hardened surface sediments there are few, if any, dolomite blocks. We presume that they were removed along with the upper part of the infilled, cavern along with the country rock as the surface continued to erode.Although it may not be possible to reconstruct a complete strati-graphic sequence involving the whole of the site, we have presented summary of evidence here that shows it is possible to trace stratigraphic relationships from the base of the Ancient Entrance to the top of the Cone and which includes the Grey Breccia and the two other bone breccias. Present work is focussed on completion of a new chronology by comparing our site magnetostratigraphy with the global polarity timescale.The speleothem deposition today in any of the caves of the Makapansgat area, with its annual rainfall of about 700mm, is extremely low. It is commonly recognised by karst geomorphologists (eg, Ford and Williams, 1989) that massive deposits of speleothem are characteristic of humid tropical to semi-tropical karsts. Hence, at the time of their formation some 3 Ma or more ago, the massive speleothem deposits are evidence for a warmer, and certainly a much wetter, climate than that of today.

The Use of 'SRT' in Sampling the Makapansgat Limeworks Hominid Palaeocave, South Africa

Introduction One major problem for researchers in the palaeocaves of South Africa has been to gain access to the stratigraphy within the caves. The palaeocaves now lie as mined-out shells, the relicts of a booming lime industry from the early 20th century. The miners were only interested in the speleothem, but inadvertently they also gave us the first evidence for the evolution of the human species in Afiica. In amongst the speleothem lay sediments full of animal fossils and more importantly those of Australopithecus, an early species of hominid. Single Rope Technique (SRT) is a skill employed by potholers to descend caves and potholes (FIGURE I), and by ‘rope access’ workers, to reach the exterior of tall structures such as high-rise flats. It has been used for the last 30 years as the standard way of descending a cave in most areas of the world. At Makapansgat, which lies in the Northern Province of South Africa some 300 km north of Johannesburg, it hasbeen successfully used to access areas ofpalaeocave stratigraphy previously unattainable except by rather dubious tactics involving huge ladders, or in completely inaccessible areas where loose rocks make the use of ladders or scaffolding too dangerous.