2004 Denver Annual Meeting (November 7–10, 2004)

Paper No. 5
Presentation Time: 2:30 PM


STRÖMBERG, Caroline A.E., Department of Palaeobotany, Swedish Museum of Nat History, Box 50007, Svante Arrhenius väg 7, Stockholm, 104 05 and WERDELIN, Lars, Department of Palaeozoology, Swedish Museum of Nat History, Box 50007, Svante Arrhenius väg 7, Stockholm, 104 05, Sweden, caroline.stromberg@nrm.se

The so-called Pikermian faunas from the late Miocene (Turolian; 8.2-7.1 Ma) of the eastern Mediterranean show a diverse mixture of browsing, mixed feeding, and grazing ungulates, and were classically thought to indicate the presence of savanna habitats similar to those in eastern Africa. Emerging evidence from stable carbon isotopes, tooth wear, and functional morphology has recently led to a re-interpretation of the Pikermian Biome as a sclerophyllous woodland or forest where grasses played a minor role. Due to differential preservation of mammal and plant remains it has been difficult to test these alternative hypotheses through direct comparison between fossil faunas and floras. We present the first paleobotanical evidence, in the form of phytolith assemblages, in direct association with Pikermian faunas. Phytoliths have previously been used to elucidate the spread of open-habitat grasses in North America during the Tertiary and are an appropriate paleoecological tool that can complement existing paleobotanical data from macrofossils and palynomorphs. Bio-opal, including phytoliths, was extracted from sediment associated with mammal specimens collected at Maragheh, northwestern Iran, and Kemiklitepe B, western Turkey. Analysis showed that phytolith assemblages are dominated by grass phytoliths (grass silica short cells), but also contain forest indicator phytoliths from dicotyledons as well as rare palm morphotypes. This suggests that grasses were important components of the ground cover in these habitats, although lack of comparative assemblages prevents a definitive interpretation of tree cover. The grass short cell assemblages are morphologically diverse and consist mainly of morphotypes of C3 grasses (pooids); forms typically produced by open-habitat grasses in the PACCAD clade (which includes e.g., chloridoids, panicoids, and arundinoids) are present in low abundances. A preponderantly C3 vegetation is consistent with stable isotope studies of paleosols of this age, as well as with the presence at both localities of ungulates shown by isotopic studies to have fed on C3 graze (e.g., Cremohipparion, Tragoportax, Pachytragus).