Paranthropus

A genus (or group of multiple genera) of fossil
hominins ranging in geological age from the
Pliocene through the early Pleistocene (~4.2–1.2
Ma = Mega-annum, or millions of years) of
Africa, the name Australopithecus comes from
Greek for “ape” (pithekos) and Latin “of the
south” (australis), for the geographical location
of the first material discovered, in South Africa.

The importance of diet in primate ecology has motivated the use of a variety of methods to reconstruct dietary habits of extinct hominin taxa. Dental microwear is one such approach that preserves evidence from consumed food items. This study is based on 44 specimens of Australopithecus africanus from Makapansgat and Sterkfontein, and 66 specimens of Paranthropus robustus from Swartkrans, Kromdraai and Drimolen. These samples enable examination of potential differences between the two assemblages of A. africanus, and among the various assemblages of P. robustus in relation to the paleoenvironmental reconstructions that have been proffered for each fossil site. Sixteen microwear texture variables were recorded for each specimen from digital elevation models generated using a white-light confocal profiler. Only two of these differ significantly between the Makapansgat and Sterkfontein samples of A. africanus. None of the microwear texture variables differs significantly among the samples of P. robustus. On the other hand, P. robustus has significantly higher values than A. africanus for 11 variables related to feature complexity, size, and depth; P. robustus exhibits rougher surfaces that comprise larger, deeper features. In contrast, A. africanus has smoother, simpler wear surfaces with smaller, shallower and more anisotropic features. As for possible habitat differences among the various sites, only a relatively small number of subtle differences are evident between the specimens of A. africanus from Makapansgat and Sterkfontein, and there are none among the specimens of P. robustus from various deposits. As such, it is reasonable to conclude that, while subtle differences in microwear textures may reflect differences in background habitats, the wear fabric differences between P. robustus and A. africanus are most reasonably interpreted as having been driven by dietary differences.

The reconstructed taphonomic and paleoenvironmental contexts of a ca. 4 million-year-old partial hominid skeleton (Stw 573) from Sterkfontein Member 2 are described through presentation of the results of our analyses of the mammalian faunal assemblage associated stratigraphically with the hominid. The assemblage is dominated by cercopithecoids (Parapapio and Papio) and felids (Panthera pardus, P. leo, Felis caracal, and Felidae indet.), based on number of identified specimens, minimum number of elements and, minimum number of individuals. In addition, the assemblage is characterized by a number of partial skeletons and/or antimeric sets of bones across all taxonomic groups. There is scant indication of carnivore chewing in the assemblage. These observations, in addition to other taphonomic data, suggest that the remains of many animals recovered in Member 2 are from individuals that entered the cave on their own—whether accidentally by falling through avens connecting the cave to the ground surface above or by intentional entry—and were then unable to escape, rather than primarily through systematic collection by a biotic, bone-accumulating agent. The taphonomic conclusion that animals with climbing proclivities (i.e., primates and carnivores) are preferentially preserved over other taxa, ultimately because of those proclivities, urges caution in assessing the fidelity of the assemblage for reconstruction of the Member 2 paleoenvironment. With that caveat, we infer that the Member 2 paleoenvironment was typified by rolling, rock-littered and brush- and scrub-covered hills, indicated by the abundant F. caracal and cercopithecoid fossils recovered and the identified presence of the extinct Caprinae Makapania broomi. In addition, the valley bottom may have retained standing water year-round, perhaps supporting some tree cover—a setting suitable for the well-represented ambush predator P. pardus and suggested by the presence of Alcelaphini. Finally, the reconstructed taphonomic and paleoenvironmental settings of Sterkfontein Member 2 are compared to penecontemporaneous sites in South and East Africa.

Resumen En este trabajo se presentan los resultados definitivos del estudio del patrón de microestriación dental vestibular de los homininos plio-pleistocénicos de África del este y del sur. Se incluyen las especies A. anamensis, A. afarensis, A. africanus, P. aethiopicus, ...

Many antelopes have an excellent sense of smell, and our human relatives such as Paranthropus robustus may have associate themselves with those antelope species during the day to avoid predation by lions, leopards and carnivores. This helps to explain why robust australopithecines successfully survived for nearly a million years on the Highveld of South Africa.

Member 1 of the Swartkrans Formation is comprised of two sedimentary infills, the Lower Bank (LB) and the Hanging Remnant (HR). Together, the LB and HR preserve fossils of early Homo and Paranthropus robustus, Earlier Stone Age lithic artifacts, purported bone digging tools and butchered animal bones. Collectively, this evidence was the first to establish the co-existence of two early Pleistocene hominid species and also led to inferences of plant root harvesting and meat-eating by one or both of those species. P. robustus is the more abundant of the two hominids at Swartrkrans, represented in Member 1 by hundreds of fossils that derive from at least 99 individuals. Thus, Swartkrans Member 1 stands as the world's single largest repository of that extinct species. Here we add to the Member 1 sample of hominid fossils with descriptions of 14 newly discovered specimens.

The large, bunodont postcanine teeth in living sea otters (Enhydra lutris) have been likened to those of certain fossil hominins, particularly the ’robust’ australopiths (genus Paranthropus). We examine this evolutionary convergence by conducting fracture experiments on extracted molar teeth of sea otters and modern humans (Homo sapiens) to determine how load-bearing capacity relates to tooth morphology and enamel material properties. In situ optical microscopy and x-ray imaging during simulated occlusal loading reveal the nature of the fracture patterns. Explicit fracture relations are used to analyze the data and to extrapolate the results from humans to earlier hominins. It is shown that the molar teeth of sea otters have considerably thinner enamel than those of humans, making sea otter molars more suscep- tible to certain kinds of fractures. At the same time, the base diameter of sea otter !rst molars is larger, diminishing the fracture susceptibility in a compensatory manner. We also conduct nanoindentation tests to map out elastic modulus and hardness of sea otter and human molars through a section thickness, and microindentation tests to measure toughness. We !nd that while sea otter enamel is just as stiff elastically as human enamel, it is a little softer and tougher. The role of these material factors in the capacity of dentition to resist fracture and deformation is considered. From such comparisons, we argue that early hominin species like Paranthropus most likely consumed hard food objects with substantially higher biting forces than those exerted by modern humans.

Foraging is constrained by the energy within resources and the mechanics of acquisition and assimilation. Thick molar enamel, a character trait differentiating hominins from African apes, is predicted to mitigate the mechanical costs of chewing obdurate foods. The classic expression of hyperthick enamel together with relatively massive molars, termed megadontia, is most evident in Paranthropus, a lineage of hominins that lived about 2.7–1.2 million years ago. Among contemporary primates, thicker molar enamel corresponds with the consumption of stiffer, deformation-resistant foods, possibly because thicker enamel can better resist cracking under high compressive loads. Accordingly, plant underground storage organs (USOs) are thought to be a central food resource for hominins such as Paranthropus due to their abundance, isotopic composition, and mechanical properties. Here, we present a process-based model to investigate foraging constraints as a function of energetic demands and enamel wear among human ancestors. Our framework allows us to determine the fitness benefits of megadontia, and to explore under what conditions stiff foods such as USOs are predicted to be chosen as fallback, rather than preferred, resources. Our model predictions bring consilience to the noted disparity between functional interpretations of megadontia and microwear evidence, particularly with respect to Paranthropus boisei.