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Abstract

The well-known South African mid-Pleistocene site of Elandsfontein has yielded an abundance of fossil fauna and artifacts (ca. 1 to 0.6 million years ago) and has produced hominin fossils, specifically a calvarium and mandibular fragment often assigned to the species Homo heidelbergensis. Elandsfontein is located within the Greater Cape Floristic Region of South Africa, in an area that is today dry, hot, and covered by marine-derived sand dunes. It is primarily vegetated by woody shrubs and sedges of the fynbos biome with minimal amounts of grass. In contrast, the Elandsfontein faunal assemblage from the mid-Pleistocene is rich in large mammalian grazing herbivores, indicating that past environment and ecology was substantially different from that of today. It is unknown whether these animals survived on local vegetation, suggesting a substantially different landscape and ecology from today, or if they migrated to nonlocal, nutrient-rich areas to obtain food, such as to the shale substrates ~ 20 to 30 km inland from Elandsfontein, where palatable grass and shrubs grow today. The strontium isotope ratios (87Sr/86Sr) of fossil teeth provide insights into the ranges of the animals recovered from Elandsfontein because they reflect the 87Sr/86Sr of plants consumed by these animals, which in turn reflect the 87Sr/86Sr of the substrates (or soils) in which those plants grew. We measured 87Sr/86Sr in 24 fossilized teeth (158 measurements) from Elandsfontein and compared these ratios with the bioavailable 87Sr/86Sr from major substrates in the region to determine if the large mammalian herbivores obtained sufficient resources locally (i.e., teeth reflect local 87Sr/86Sr) or if they traveled inland to find food. The distribution of bioavailable 87Sr/86Sr for coastal marine sands range from 0.709380 to 0.711690; most of this range is lower than the bioavailable 87Sr/86Sr for granite, sandstone, and shale substrates in the region which range from 0.711421 to 0.723563. 87Sr/86Sr of fossil teeth of carnivores, large herbivores, and rodents from Elandsfontein fall within the 87Sr/86Sr range of the marine sands. Our results indicate localized habitation patterns for a diversity of large African mammals, including communities of grazing herbivores, and a resource-rich environment that made mid-Pleistocene Elandsfontein and coastal southwestern South Africa attractive to hominins for which there is no modern analogue.