Lions as Bone Accumulators? Paleontological and Ecological Implications of a Modern Bone Assemblage from Olduvai Gorge.

Analytic models have been developed to reconstruct early hominin behaviour, especially their subsistence patterns, revealed mainly through taphonomic analyses of archaeofaunal assemblages. Taphonomic research is used to discern which agents (carnivores, humans or both) generate the bone assemblages recovered at archaeological sites. Taphonomic frameworks developed during the last decades show that the only large-sized carnivores in African biomes able to create bone assemblages are leopards and hyenas. A carnivore-made bone assemblage located in the short-grassland ecological unit of the Serengeti (within Olduvai Gorge) was studied. Taphonomic analyses of this assemblage including skeletal part representation, bone density, breakage patterns and anatomical distribution of tooth marks, along with an ecological approach to the prey selection made by large carnivores of the Serengeti, were carried out. The results show that this bone assemblage may be the first lion-accumulated assemblage documented, although other carnivores (namely spotted hyenas) may have also intervened through postdepositional ravaging. This first faunal assemblage potentially created by lions constitutes a new framework for neotaphonomic studies. Since lions may accumulate carcasses under exceptional circumstances, such as those documented at the site reported here, this finding may have important consequences for interpretations of early archaeological and paleontological sites, which provide key information about human evolution.

How Far into Europe Did Pikas (Lagomorpha: Ochotonidae) Go during the Pleistocene? New Evidence from Central Iberia.

This paper reports the first find of pika remains in the Iberian Peninsula, at a site in central Spain. A fragmented mandible of Ochotona cf. pusilla was unearthed from Layer 3 (deposited some 63.4±5.5 ka ago as determined by thermoluminescence) of the Buena Pinta Cave. This record establishes new limits for the genus geographic distribution during the Pleistocene, shifting the previous edge of its known range southwest by some 500 km. It also supports the idea that, even though Europe's alpine mountain ranges represented a barrier that prevented the dispersal into the south to this and other taxa of small mammals from central and eastern Europe, they were crossed or circumvented at the coldest time intervals of the end of the Middle Pleistocene and of the Late Pleistocene. During those periods both the reduction of the forest cover and the emersion of large areas of the continental shelf due to the drop of the sea level probably provided these species a way to surpass this barrier. The pika mandible was found accompanying the remains of other small mammals adapted to cold climates, indicating the presence of steppe environments in central Iberia during the Late Pleistocene.

Differential predation by age and sex classes in blue wildebeest in Serengeti: study of a modern carnivore den in Olduvai Gorge (Tanzania).

Age and sex selection of prey is an aspect of predator ecology which has been extensively studied in both temperate and African ecosystems. This dimension, along with fecundity, survival rates of prey and mortality factors other than predation are important in laying down the population dynamics of prey and have important implications in the management of species. A carnivore den located in the short-grassland ecological unit of the Serengeti was studied. Sex- and age- class (using five age categories) of the wildebeest remains recovered were analyzed through horn morphology, biometrics of the bones and tooth wear patterns. We compared our results with previous studies from lion and hyaena kills through multivariate analyses. Seasonality of the accumulation was analyzed through tooth histology. PCA and CVA results show that age class selection by predators depends on season, habitat-type, and growth rate of the wildebeest population. Female-biased predation was found to contradict classical hypotheses based on territorial male behaviour. The lion and spotted hyaena showed strong selection on age classes, contrary to previous studies. Migratory wildebeest sex ratio is regulated through differential predation by seasons and female deaths in the wet season are a trade-off for population stability. These data are crucial for an effective management of the species and the new method created may be useful for different carnivore species and their prey.