Plio-Pleistocene macroplant fossil remains and phytoliths from Lowermost Bed II in the eastern palaeolake margin of Olduvai Gorge, Tanzania

Fossil macroplants and phytoliths occur in the sediments of the palaeoanthropological site of Olduvai Gorge, northern Tanzania. Current research on hominin land use in the Basin during the Plio-Pleistocene has a strong palaeoenvironmental emphasis oil the palaeovegetation in particular. The occurrence of macroplants and phytoliths at Olduvai, and their usefulness and reliability for palaeovegetation interpretation are assessed here for the first time. Modern reference collections from analogous environments have been established and used to identify the fossil taxa from the eastern palaeolake margin of Lowermost Bed II as the test case for very detailed spatially and temporally constrained vegetation reconstruction. Fourier Transform Infrared Spectrometry (FTIR) analysis was used to identify the minerals of the fossil sediments. Modern plants produce more phytoliths than are preserved in the fossil soils but there were sufficient numbers to show diverse and changing vegetation over short time periods Silicified macroplant fragments of sedge culms and dicot stems occur with phytoliths, but II not always represent the same plant taxa. A more complex flora was shown when using both forms of fossil plants. During Lowermost bed II times, at the locality of FLKN monocots and dicots occurred, indicating the presence of marshland and grassland after the deposition of Tuff IF. At VEK, the phytoliths indicate a shift in dominance from dicots to monocots to a mixture of the two and including palms. At HWKEE, initially palms dominated then there was it mixture of palms, grasses and dicots. The vegetation at MCK comprised dicots, monocots sedges and grasses. This detailed vegetation data complements the more broad scale vegetation interpretations that have been deduced from the pollen, isotopes and faunal data sets. (c) 2005 Elsevier Ltd and INQUA. All rights reserved.