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

  • Lloyd RossouwEmail author
  • Louis Scott
Chapter
Part of the Vertebrate Paleobiology and Paleoanthropology Series book series (VERT)

Abstract

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.

Keywords

Grass silica Palynology Pollen preservation Past environment Vegetation change 

Notes

Acknowledgements

We thank Terry Harrison for the invitation to take part in the Laetoli project. LS collected most of the pollen samples during the 2000 field season with the help of team members especially John Kingston, while Terry Harrison and LR collected more during following seasons. LR collected the phytolith samples during the 2004 field season with the help of team member John Kingston. Charles Peters kindly provided unpublished data about his research on termitaria and phytolith preservation in East Africa. Petrus Chakane processed the samples chemically in the palynology laboratory at the UFS. The National Research Foundation (NRF) supported laboratory work (Gun 2053236). Any opinions, findings, and conclusions are those of the authors and the NRF does not accept any liability in regard thereto. Travel funds and field support were provided by an NSF grant (BCS-0309513) to Terry Harrison.

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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  1. 1.Department of ArchaeologyNational MuseumBloemfonteinSouth Africa
  2. 2.Department of Plant SciencesUniversity of the Free StateBloemfonteinSouth Africa

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