TAPHONOMY AND PALEOECOLOGY OF OLDUVAI BED-I (PLEISTOCENE, TANZANIA)

Detailed taxonomic and taphomonic studies of rodents and palaeoecologi cal analysis have been undertaken to investigate faunal change in Oldu vai Bed-I. The palaeoenvironments inferred from rodent faunas recorded in Olduvai Bed-I suggest a change between the middle (FLK+FLKNN) and the top of the series (FLKN). Changes have also been observed from tax onomic studies of large mammals and from palynological studies. These differences have been attributed in the past to climatic change, but t aphonomic studies suggest a more complex scenario. The environment at Olduvai Bed-I is here interpreted through analysis of fossil faunas an d fossilization processes. Identification of the causative agents that could have altered the faunal composition provides information on the environment and on the nature of the change observed between the midd le and top of Bed-I. This information can then be used to rest conflic ting hypotheses about the origins and amount of faunal and pollen chan ge. Results show evidence of predation in all units of Bed-I and can b e attributed to different predators along the series. Different predat or behaviours explain some of the variability observed by previous aut hors in the small mammal species composition between the middle and th e top of Bed-I. After taking taphonomy into account, the remaining fau nal differences point to environmental differences between middle and upper Bed-I and even greater within the upper Bed-I sequence. These di fferences go beyond the range that is present: today in the tropical w oodland-savanna biome. Our interpretation of the palaeoenvironments is that the middle Bed-I faunas indicate a very rich closed woodland env ironment, richer than any part of the present-day savanna biome in Afr ica, changing to less rich woodland in upper Bed-I with a trend toward s more open and seasonal woodlands at the top of the series. (C) 1998 Academic Press Limited.