Lloyd Rossouw

The diet of Australopithecus sediba

Specimens of Australopithecus sediba from the site of Malapa, South Africa (dating from approximately 2 million years (Myr) ago) present a mix of primitive and derived traits that align the taxon with other Australopithecus species and with early Homo. Although much of the available cranial and postcranial material of Au. sediba has been described, its feeding ecology has not been investigated. Here we present results from the first extraction of plant phytoliths from dental calculus of an early hominin. We also consider stable carbon isotope and dental microwear texture data for Au. sediba in light of new palaeoenvironmental evidence. The two individuals examined consumed an almost exclusive C3 diet that probably included harder foods, and both dicotyledons (for example, tree leaves, fruits, wood and bark) and monocotyledons (for example, grasses and sedges). Like Ardipithecus ramidus (approximately 4.4 Myr ago) and modern savanna chimpanzees, Au. sediba consumed C3 foods in preference to widely available C4 resources. The inferred consumption of C3 monocotyledons, and wood or bark, increases the known variety of early hominin foods. The overall dietary pattern of these two individuals contrasts with available data for other hominins in the region and elsewhere.

First hominine remains from a ~1.0 million year old bone bed at Cornelia-Uitzoek, Free State Province, South Africa

We report here on evidence of early Homo around 1.0 Ma (millions of years ago) in the central plains of southern Africa. The human material, a first upper molar, was discovered during the systematic excavation of a densely-packed bone bed in the basal part of the sedimentary sequence at the Cornelia-Uitzoek fossil vertebrate locality. We dated this sequence by palaeomagnetism and correlated the bone bed to the Jaramillo subchron, between 1.07 and 0.99 Ma. This makes the specimen the oldest southern African hominine remains outside the dolomitic karst landscapes of northern South Africa. Cornelia-Uitzoek is the type locality of the Cornelian Land Mammal Age. The fauna contains an archaic component, reflecting previous biogeographic links with East Africa, and a derived component, suggesting incipient southern endemism. The bone bed is considered to be the result of the bone collecting behaviour of a large predator, possibly spotted hyaenas. Acheulian artefacts are found in small numbers within the bone bed among the fossil vertebrates, reflecting the penecontemporaneous presence of people in the immediate vicinity of the occurrence. The hominine tooth was recovered from the central, deeper part of the bone bed. In size, it clusters with southern African early Homo and it is also morphologically similar. We propose that the early Homo specimen forms part of an archaic component in the fauna, in parallel with the other archaic faunal elements at Uitzoek. This supports an emergent pattern of archaic survivors in the southern landscape at this time, but also demonstrates the presence of early Homo in the central plains of southern Africa, beyond the dolomitic karst areas.

Phytoliths and Pollen, the Microscopic Plant Remains in Pliocene Volcanic Sediments Around Laetoli, Tanzania

We analyzed sediment samples collected from several localities at different stratigraphic levels at Laetoli (i.e., Lower Laetolil Beds [LLB], Upper Laetolil Beds [ULB] and the overlying Upper Ndolanya Beds [UNB]) to establish a record of vegetation succession spanning intermittent periods between 4.3 and 2.66 Ma during the Pliocene. No reliable pollen spectra were found, but phytoliths, especially those of grasses (Poaceae), were investigated. A considerable time interval of deposition for the sequence, combined with a relatively low sample yield, allowed us to present only a low-resolution sequence of environmental changes, but one with marked grass cover variation. Grass was a ubiquitous, but never a dominant vegetation component in the LLB, ULB and the UNB sequences, with a general succession from mainly C3 grass types in the LLB and older ULB levels to more C4 grass types in the younger ULB and UNB. The record lends support to fossil herbivore analyses and δ13C isotope studies, which suggest more heterogeneous habitats and a combination of C3/C4 grassland conditions in the ULB and UNB sequences (Andrews 1989; Kingston and Harrison 2007; Kovarovic and Andrews 2007). Productive samples suggest wet, C3 conditions in the LLB and potentially dry, C3 conditions in the lower part of the ULB. A shift from drier to more mesic C4 grass conditions is recorded in the upper part of the ULB. Arid C4 grassland environments occurred during UNB deposition.

Palaeoenvironmental Context of Coprolites and Plant Microfossils from Unit II. Azokh 1

Poor pollen preservation in cave deposits is due to oxidation and increasing scarcity of pollen with distance from the cave entrance. After an attempt to obtain pollen grains from the sediments in Azokh 1 (Lesser Caucasus) failed, two coprolites from Unit II were investigated for their microfossil contents. They contained few diatoms (including the rare Pliocaenicus), even less pollen but numerous phytoliths that were compared with those in selected levels of cave deposits and modern soil from outside. Grass silica short cell phytoliths give evidence of vegetation typical of a temperate climate for Unit II, which included C3 grasses. Not only the coprolites from Azokh are useful but the whole sequence of deposits has good potential for palaeoclimatic reconstruction based on for phytolith studies. The diatoms observed indicate feeding from a relatively moist terrestrial environment and availability of lake and/or running water.