Early Pleistocene fossil wood from Olduvai Gorge, Tanzania

摘要

Olduvai Gorge is a well-known East African site for early hominid and faunal remains, as well as stone tools and artefacts. Through the efforts of a multidisciplinary research team, OLAPP (Olduvai Landscape and Palaeoanthropology Project), the sedimentology, tephrostratigraphy, dating, mapping and palaeoclimatic interpretations are being used to put the whole ecosystem into context to achieve a better understanding of hominid occupation and behaviour. The palaeolake, together with the alluvial fan and wetland environment, have shifted and fluctuated under the influeace of climatic change, tectonic faulting, lava flows and ashfalls. Numerous fossil plants have been recovered from these sediments, including sedges, grasses, twigs, pollen, phytoliths and wood. One sample of fossil wood has been identified as Guibourtia coleosperma (Caesalpiniaceae), a relatively uncommon tree, which today grows in Angola, Botswana, Namibia, Zambia and Zimbabwe. This species grows on Kalahari sands but must have had a wider distribution in the past. The occurrence of this tree in lowermost Bed Ⅱ (approximately 1.81-1.78 Ma) indicates that there were large trees in the close vicinity, and that there were periods of wetter climate. Large trees would have provided some shelter or safety for the hominids from other scavengers.