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Functional relationships between diet and tooth morphology form an integral part of paleontological research. The detailed description of occlusal relief and wear patterns of molars provides information about food ingestion and mastication. In early hominids overall molar morphology is fairly similar. Size measurements, such as buccolingual or mesiodistal diameter and 2-D cusp area of hominid molars show considerable overlap. The pioneering works of Butler, Mills, Hiiemae, Kay, Maier and others have shown that the wear pattern on the occlusal surface seems to reflect mastication behavior as an indication of diet. However, most of the interpretations are based on two-dimensional analyses. Occlusal relief measured in 3-D highlights functionally important features useful for quantifying the complex wear patterns on hominid teeth. However, until recently they could not be measured because techniques and methods were lacking. Nevertheless the results of 2-D analyses so far demonstrate that the occlusal surface of teeth records a significant part of the life history of an individual. The 3-D analysis of wear patterns on hominid teeth may provide additional information regarding the relationships between diet, chewing behavior and early hominid evolution. In this case study we employ a new 3-D approach to compare details on the occlusal surface of worn molars of Australopithecus afarensis, Australopithecus africanus and Paranthropus robustus in order to examine possible differences in tooth wear patterns. High resolution optical topometry enables us to measure parameters on 3-D computer models of teeth. Here, we compare various occlusal morphologies of worn lower second molars and attempt to interpret function, taking dental and masticatory principles into account. Our results indicate that diverse modes of occlusal wear in Australopithecus and Paranthropus are evident. A closer look at the occlusal relief and wear facet pattern shows that an assortment of mechanisms for crushing, shearing and grinding on a single tooth are common, since orientation and inclination of wear facets vary. The fact that A. afarensis molars show diverse functional areas with little variation among individuals suggests it had a dental toolkit to cope with a wide range of food qualities and may indicate a species-specific dietary spectrum. A. africanus and P. robustus molars, with their pronounced and relatively rapid flattening of crown relief and diverse individual wear patterns, point towards hard-object feeding and greater intraspecific variation in diet. P. robustus, however, with somewhat higher occlusal relief, can be interpreted as an omnivorous generalist with hard objects as fall-back foods. [ABSTRACT FROM AUTHOR]

The vertebrate fauna of the Chiwondo Beds in Northern Malawi is heavily biased towards the preservation of large terrestrial mammals, the majority being ungulates. The faunal diversity resembles an African shortgrass plains assemblage. The taxonomic diversity is nevertheless low, emphasizing an incomplete fossil record. Based on modern bovid representation in African game parks, statistical tests show that the Chiwondo bovid assemblage consists of a mixture of species found in the Somali-Masai and the Zambezian ecozones. The composition of the terrestrial fauna is similar to Swartkrans 1 and the Upper Ndolanya Beds. The fossil assemblages can be assigned to three biostratigraphic time intervals that date from older than 4.0 Ma to less than 1.5 Ma. The occurrence of Paranthropus boisei at a lake margin site in the Chiwondo Beds corresponds to robust australopithecine-bearing localities near Lake Turkana, Kenya. A case study showed that the investigated death assemblage on a delta plain in the Malema region was subject to heavy modification after deposition. This has affected the size distribution, the frequencies of skeletal elements, and thus the taxonomic composition. High-density skeletal elements such as molars and partial mandibles dominate the assemblage. The Homo rudolfensis locality at Uraha has a different faunal composition, the preservation in a paleosol points to a different taphonomic history and the Uraha area encompasses a longer time span. [ABSTRACT FROM AUTHOR]