Biomarker records of late Neogene changes in northeast African vegetation

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Abstract
Open savannah grasslands (dominated by C4 plants) became a significant component of northeast African vegetation during the late Neogene. We present molecule-specific carbon isotopic mea- surements of terrestrial plant biomarkers preserved in marine sed- iments off northeast Africa that allow reconstruction of orbital- scale vegetation changes in short time windows over the past 9.4 m.y. The biomarker data show large-amplitude vegetation vari- ability as early as 3.8 Ma, with the greatest C4 expansion occurring after 3.4 Ma. We sampled orbital-scale oscillations of up to 5‰, almost as large as the observed late Neogene range of 7‰, sug- gesting that large and repeated oscillations between more open and more closed landscapes were an important aspect of northeast Af- rican vegetation change during the past 4 m.y.