Miocene Flora Research Articles

Miocene to Pleistocene floras and climate of the Eastern Himalayan Siwaliks, and new palaeoelevation estimates for the Namling–Oiyug Basin, Tibet

Four fossil floras ranging in age from the mid Miocene to the early Pleistocene from the eastern Siwaliks near Darjeeling and in Arunachal Pradesh (AP) were compared taxonomically and subjected to a CLAMP (Climate Leaf Analysis Multivariate Program) analysis using a new calibration dataset that includes sites from India, southern China and Thailand and high resolution gridded climate data. Two lower Siwalik mid Miocene floras yielded almost the same values suggesting mean annual temperatures (MATs) of 25.4 and 25.3°C±2.8°C (all uncertainties ±2 sigma) with warm month mean temperatures (WMMTs) of 28.4 and 27.8±3.39°C and cold month mean temperatures (CMMTs) of 17.9 and 21.3±4°C. Precipitation estimates have high uncertainties but suggest a weak monsoon with growing season precipitations of 242±92cm for Darjeeling and 174±92cm for AP. Leaves from the middle Siwalik (Pliocene) sediments of AP indicate a lowering of the MAT to 23.7°C, a function of cooler winter months (CMMT 16.9°C). The AP early Pleistocene temperatures and rainfall were similar to those of the mid Miocene. Changes in the monsoon index suggest that in the AP area there has been little change in the intensity of the monsoon since mid Miocene time, while further west at Darjeeling there has been an intensification since the mid Miocene. Mid Miocene CLAMP-derived enthalpy estimates provide sea level (<200a.m.s.l.) data for a re-evaluation of the palaeoelevation of a 15Ma flora from the Namling–Oiyug Basin, southern Tibet. Enthalpy values from Darjeeling and AP were 354.1 and 355.8±10.3kJ/kg respectively, while that derived from the Namling–Oiyug flora was 296.3kJ/kg. This yields a palaeoelevation of 5888m for the Namling site using the Darjeeling enthalpy estimate as a sea level datum and 6065m using the AP assemblage. The combined uncertainty is ±728m. Model corrected enthalpy trends at sea level across palaeolatitude and longitude reduce the mean elevation to 5.54km. These elevations are higher than earlier estimates from the same site (but within uncertainty) and the corrected mean is ~1km higher than the present day basin floor elevation in the region, suggesting some deflation since 15Ma associated with east–west extension, particularly if a shift in the locus of deformation and uplift south to the Himalayas in post middle Miocene times relieved N–S compressional stress on southern Tibet.

Early Miocene flora from the Valjevo-Mionica Basin (Western Serbia)

Early Miocene flora from the Valjevo-Mionica Basin (Western Serbia)

Late Miocene Flora from Karlovo Basin (Southern Bulgaria). New Floristic and Palaeoecological Data

This paper presents the results from taxonomical and palaeoecological analysis of the Late Miocene flora from Karlovo basin. The studied flora comes from borehole C-556 located in the eastern part of the basin. The percentage contribution of individual taxa allowed us to dierentiate the main vegetation types in the area. The pollen data indicate widest distribution of mixed mesophytic forest communities (Quercus, Fagus, Ulmus, Carya, Pterocarya, Carpinus, Betula), existence of hygrophytic (swamp) forests and distribution of the herbaceous palaeocoenoses (high values of Poaceae, Chenopodiaceae, Apiacea, Asteraceae, Artemisia, Thalictrum, Polygonum, Caryophyllaceae, Cichorioideae, Lamiaceae). According to the pollen data, the palaeoflora from Karlovo basin reflects warm-temperate climate during the studied period.

The Miocene conifer flora of Balcombe Bay, Victoria, Australia

Fossil conifers from an early Miocene flora at Balcombe Bay near Melbourne, Australia, are described and illustrated. The most prominent elements are Araucaria balcombensis Selling emend. R.S.Hill and Dacrycarpus mucronatus P.M.Wells &amp; R.S.Hill, and several other unidentified podocarp leaves are represented. Ovuliferous cones of D. mucronatus are described, along with isolated araucarian microsporophylls and podocarp pollen cones – both with pollen in situ. The floristic elements are similar to Eocene–Oligocene flora described from Tasmania, and indicate that these floras extended to now mainland Australia and persisted into the Miocene. They are indicative of a wetter and warmer climate than the present time.

A morphotype catalog and paleoenvironmental interpretations of early Miocene fossil leaves from the Hiwegi Formation, Rusinga Island, Lake Victoria, Kenya

Early Miocene deposits on Rusinga Island (Lake Victoria, Kenya) contain an abundance of faunal and floral remains. Despite the attention that has historically been given to the early Miocene fauna from Rusinga Island, little attention has been given to the early Miocene fossil floras and to date no studies have described fossil leaf morphotypes from Rusinga Island. Here, we present a morphotype catalog of fossil leaves collected from the Grit Member of the Hiwegi Formation on Rusinga Island. We describe 14 morphotypes, comprised of 12 dicotyledonous angiosperms and two monocotyledonous angiosperms, as well as two distinct dicotyledonous angiosperm leaf fragments. Characteristics of the flora and sedimentological evidence, coupled with previous research, suggest that the local paleoenvironment was a riparian habitat within a patchwork of woodland and forested biomes in what was likely a warm climate. This work represents an important first step in understanding the early Miocene vegetation of Rusinga Island, and highlights both the need and potential for future research on these early Miocene floras.

Paleoclimatic estimation reveals a weak winter monsoon in southwestern China during the late Miocene: Evidence from plant macrofossils

The late Miocene Xianfeng flora of Yunnan Province, southwestern China, was chosen to reconstruct the paleoclimate and the intensity of the Asian monsoon. Three available quantitative climate reconstruction methods from fossil plants, i.e. Leaf Margin Analysis (LMA), the Climate Leaf Analysis Multivariate Program (CLAMP), and the Coexistence Approach (CA) were used in this study. MATs (mean annual temperatures) resulting from these three approaches (i.e., LMA: 17.2±2.38°C; CLAMP: 15.43±1.25°C; CA: 17.2–21.7°C) appear to have been higher than the present (14.9°C), suggesting a much warmer climate in the late Miocene. Both the growing season precipitation (GSP) from CLAMP (1908.7±217.7mm) and mean annual precipitation (MAP) from CA (1206.0–1613.0mm) estimates are higher than modern values (1003.2mm (GSP) and 1038mm (MAP) respectively) indicating a more humid climate during the late Miocene. By comparing these with climates reconstructed from neighboring late Miocene floras, we conclude that the general late Miocene climate appears warmer and more humid than present conditions in southwestern China. Furthermore, the evident differences in estimated monthly temperatures between the summer and winter, and precipitations between the humid and dry seasons indicate the existence of seasonality, though not as strong as that of today. Difference in precipitation of dry season indicates a marked strengthening in the winter monsoon since the late Miocene. A new monsoon intensity index has also been defined based on precipitation seasonality to investigate the intensity of the Asian monsoon.

502 Miocene flora from Ninghai in eastern Zhejiang and palaeoclimatic implication

502 Miocene flora from Ninghai in eastern Zhejiang and palaeoclimatic implication

Micromorphological, geochemical, and diagenetic characterization of sirenian ribs preserved in the Late Miocene paleontological site of Cessaniti (southern Calabria, Italy)

The site of Cessaniti (Vibo Valentia, Italy) has been well known since the 19th century for the richness and good preservation of its Miocene fauna and flora. The sedimentary succession of the site represents a paralic system that evolved toward an open-marine environment recording the Tortonian transgression. The fossil assemblage contains rich invertebrate (corals, bivalves, gastropods, brachiopods, echinoids, benthic and planktonic foraminifers) and vertebrate faunas (proboscideans, rhinoceroses, giraffids, bovids, sirenids, marine turtles, and fish remains). The fossils recovered at the Cessaniti site have a relevant role in phylogenetic studies and paleogeographic reconstructions of Late Miocene environments of the southern Italy. This research is focused on the microstructure and preservation state of the fossil bones. Samples of Metaxytherium sp. bones have been analyzed to understand the diagenetic profile of the bone assemblages that characterizes the taphonomic history of the Cessaniti site. The analyses provided a comprehensive account of how bone mineral (bioapatite) has been altered and demonstrated that the post-burial processes did not significantly affect the micromorphological and biogeochemical features of the bones. The excellent preservation state of the bones strengthens the importance of the Cessaniti site for studies of the Mediterranean Miocene vertebrate fauna.

포항 분지 연일층군(마이오세)의 두호층에서 산출된 Albizia miokalkora Hu and Chaney

Three legume fossils collected from the Miocene Duho Formation of Yeonil Group in the northern Pohang Beach, Gyeongsangbug-do, Korea were described as Albizia miokalkora Hu and Chaney. This species has only appearing in the Miocene floras of Korea, China and Japan until present. It has wide distribution from warm temperate to subtropical-tropical regions but, the diversity of the species of Albizia is not so high. It is considered that the fossil Albizia miokalkora Hu and Chaney might have adapted to the warm climate such as warm temperate climate and subtropical to tropical climate.

Precipitation patterns in the Miocene of Central Europe and the development of continentality

Understanding climate patterns, with their decisive influence on plant distribution and development, is crucial to understanding the history of vegetation patterns in Europe during the Miocene. This paper presents the detailed analyses of several precipitation parameters, including monthly precipitation of the wettest, driest and warmest months, for five Miocene stages. In conjunction with seasonality of temperature, those parameters provide a meaningful measure of continentality and can help to document Miocene climate changes and patterns and their possible influence on vegetation. Climate reconstructions provided here are entirely based on palaeobotanical material. In total, 169 Miocene floras were selected, including 14 Burdigalian, 41 Langhian, 40 Serravallian, 36 Tortonian, and 38 Messinian localities. All floras were analysed using the Coexistence Approach. The analysis of several precipitation parameters, the statistical inter-correlation of results, and the comparison with modern patterns provides a comprehensive account on Miocene precipitation. Miocene climatic changes after the Mid Miocene Climatic Optimum (MMCO) are evidenced in our data set by three major factors, i.e. (1) increasing seasonality of temperature, (2) changes in the annual distribution of precipitation towards a precipitation peak in summer, and (3) a late increase of longitudinal gradients of precipitation parameters. Evidence of continental climate in Eastern Europe first appears during the Messinian. In addition to changes in temperature, shifts in the annual distribution of precipitation may have played a major role in post-Langhian climate changes. However, the most significant climatic transformations occurred later, from the end of Miocene through to the present. Several authors have described patterns of vegetation development in Europe that are in good agreement with our finding of the first evidence for continental climate in Eastern Europe during the Messinian. Our data do not support an onset of opening of vegetation during the Tortonian or even earlier, as has been described for some parts of Eastern and Southern Europe. Possibly either non climatic parameters influenced such an early development, or our data lack the required resolution and/or spatial coverage to fully decipher the influence of continentality on vegetation and to correlate climate and vegetation statistically. Nevertheless, climatic data that quantify continentality can provide a sound basis for explaining the expansion of grassland in Eurasia.

Euphorbiaceae: Acalyphoideae fossils from early Miocene New Zealand: Mallotus– Macaranga leaves, fruits, and inflorescence with in situ Nyssapollenites endobalteus pollen

An early Miocene (ca. 23 Ma) flora from the Foulden Maar diatomite deposit, Otago, southern New Zealand contains numerous organically-preserved fossil leaf compressions, flowers and fruits. A fossilised male partial lax inflorescence carrying in situ pollen of the type Nyssapollenites endobalteus (McIntyre) Kemp & Harris is assigned to Euphorbiaceae, subfamily Acalyphoideae, tribe Acalypheae. Leaves from the same site are referred to the Mallotus–Macaranga clade (Euphorbiaceae: Acalyphoideae) on the basis of leaf architecture and epidermal features and described as Malloranga fouldenensis gen. et sp. nov. In addition, euphorbiaceous trilobed capsular fruits are assigned to the form genus Euphorbiotheca as E. mallotoides sp. nov. and an immature infructescence is also described. The inflorescence, pollen, leaves and fruits blew or fell into a small enclosed maar lake and must have been derived from trees or shrubs growing around the lake margin.

Miocene vegetation and climate dynamics in Eastern and Central Paratethys (Southeastern Europe)

From the Cretaceous to modern time the earth's climate system has changed repeatedly from a greenhouse to an icehouse. The Miocene appeared as the last warm episode in earth history, prior to the establishment of large Northern Hemisphere ice sheets. Furthermore, the Miocene was characterized by both, large-scale marine transgressions and pronounced episodes of regressions, e.g. opening and closure of marine corridors as well as appearance and disappearance of lakes and swamps. The sea-level changes and instability of the climate system strongly influenced not only marine ecosystems but also the terrestrial biota. To throw new light on the Miocene evolution of European ecosystems and climate dynamics, we compared plant assemblages from southeastern Europe. Palaeogeographically this area is a transitional belt between Tethyan and Paratethyan realms, and it thus constitutes a crucial geographical position when one tries to comprehend the exchange pathways of various floristic elements, appearance and evolution of steppe vegetation, interaction between forest and steppe vegetation, and of course the corresponding climates influencing the vegetation dynamics. Both macro- and microfloristic plant associations were considered in our analysis. Large palaeofloristic and palaeocoenotic transformations occurred during the Miocene. The Early to Middle Miocene flora is rich and diverse in thermophilous elements, which formed polydominant mesophytic to hygromesophytic forests. Early Miocene climate was warm and humid with mean annual temperatures mainly above 16 °C and annual rainfalls over 1000 mm. The Middle Miocene was the warmest period of the whole Miocene, with annual temperatures ranging from 17 °C to 19 °C and winter temperatures from 7 °C to 12.5 °C. Climatic changes after the Miocene climatic optimum caused changes in floristic composition and vegetation structure. The vegetation shows a decreasing trend in abundance of palaeotropic and thermophilous elements, reduction of macrothermic elements, and disappearance of evergreen laurel forests. Together with these changes is a corresponding increase in the role of arctotertiary species in plant communities, and they became dominants in mesophytic forests. The available data indicate that major vegetation changes occur in the late Miocene. This period is characterized by more diverse climatic conditions, which were directed by global climatic changes and probably complicated by regional palaeogeographic reorganizations and tectonic processes. Slight cooling and some drying is recorded for the beginning of the Late Miocene, followed by fluctuations of palaeoclimate parameters observed which display cycling change of humid/dryer and warmer/cooler conditions. Our study provides a new insights on the Miocene vegetation and climate dynamics and evolution in Southeastern Europe.

Prosopisinoxylon anciborae nov. gen. et sp. (Leguminosae, Mimosoideae) from the Late Miocene Chiquimil Formation (Santa María Group), Catamarca, Argentina

A new genus and species of fossil wood with Leguminosae (Mimosoideae) affinities from the Late Miocene Chiquimil Formation (Santa María Group) in Catamarca Province, Argentina, is described. Prosopisinoxylon anciborae Martínez lacks growth rings, is diffuse porous, has vessels of two distinct diameters, simple perforation plates, alternate and vestured intervessel pits, rays commonly 1 to 9 seriate and confluent axial parenchyma with prismatic crystals in chambered diffuse paratracheal parenchyma cells. This taxon has the greatest similarity to extant genus Prosopis L. Based on the presence of Prosopis fossil leaves and pollen in the Miocene San José and Morterito formations, Argentina, the genus expands its distribution in the past, showing that Prosopis was an important element of Miocene floras of northwestern Argentina and would explain its high extant diversity.

Taphonomy of the early Miocene flora, Hiwegi Formation, Rusinga Island, Kenya

A fossil flora was collected in situ from early Miocene deposits at site R117 in the Hiwegi Formation of Rusinga Island contemporaneous with and in close proximity to the sites from where the anthropoid primates were recovered. The flora exhibits a spatially and temporally patchy distribution of fruits and seeds, mixed with twigs of various sizes, fragments of wood, bark, and leaves, all with random orientations and very low depositional dips. There has been minimal transport and the flora evidently accumulated as in situ litter beneath local vegetation. Based on Nearest Living Relatives (NLR) of fruits and seeds, the vegetation represented is a deciduous broad-leaved woodland with continuous canopy, with trees, shrubs, lianas, and climbers, reminiscent of the structure of the modern vegetation in the steep-sided protected valleys in the Laetoli-Endulen area. The interpretation of the vegetation is supported by the presence of twigs, wood, and bark fragments from larger diameter axes. Climbers are represented by twining stem fragments as well as by a wide variety of distinctive fruits and seeds. The proportion of fossilised thorny twigs represents only 3% of the twig collections, and there are no unequivocal forest trees amongst the NLR. No grasses were present; monocotyledons are only represented by a single date palm stone. No conifer seeds or cones have been recovered, and there are no coniferous leafy shoots.

Quantitative climate reconstructions of the late Miocene Xiaolongtan megaflora from Yunnan, southwest China

The late Miocene Xiaolongtan megaflora from Kaiyuan in southeast Yunnan (23°48′45″N, 103°11′52″E, 1050 m a.s.l.) was chosen for palaeoclimatic reconstruction using three quantitative techniques, i.e. the Coexistence Approach (CA), Leaf Margin Analysis (LMA), and the Climate–Leaf Analysis Multivariate Program (CLAMP). The reconstructed climatic parameters are also compared with those of the two adjacent Miocene floras currently available in Yunnan, i.e. the early to middle Miocene carpological Mangdan flora (24°24′N, 97°49′E, 1620 m a.s.l.) and the late Miocene Lühe palynoflora (25°10′N, 101°22′E, 1930 m a.s.l.). Quantitative analyses of the Xiaolongtan flora supports the previous qualitative results of a southern, humid subtropical climate, being more humid and having a slightly higher mean annual temperature (MAT) than today. The MATs calculated by CA, LMA, and CLAMP overlap (16.7–19.2 °C, 22.3 ± 2.05 °C, 18.1 ± 1.2 °C, respectively) and are close to the present day value (19.7 °C). The overlapping of temperatures derived using the three techniques is unusual and probably related to the low latitude of the Xiaolongtan area and the southern subtropical nature of its vegetation. Both the mean temperatures of the warmest month (WMT) and of the coldest month (CMT) reconstructed by CA (WMT = 25.4–26.0 °C, CMT = 7.7–8.7 °C) and CLAMP (WMT = 25.9 ± 1.6 °C, CMT = 10.8 ± 1.9 °C) are similar to those of today (WMT = 24.3 °C, CMT = 12.8 °C), but great changes appear in the mean annual precipitation (MAP). The CLAMP results suggest a higher precipitation (1964 ± 335.9 mm) than CA (1215–1639 mm), but they are much higher than the present MAP (820.5 mm). This is consistent with results from the Lühe palynoflora, which also developed under a warmer subtropical climate with higher precipitation (803.6–1254.7 mm) than that of today (815.9 mm). In contrast, the Mangdan flora, situated in a more complicated topographic region to the west of Xiaolongtan and near the Sino-Myanmar border, implies a slightly lower precipitation (1170–1300 mm) than that of today (1300–1400 mm). Overall, the wetter climate during the late Miocene around the Xiaolongtan area suggests that the Himalayas had not yet uplifted to its present altitudes at that time.

Vegetational and climatic investigations in the Early Miocene lacustrine deposits of the Güvem Basin (Galatean Volcanic Province), NW Central Anatolia, Turkey

The palynological analysis of the Burdigalian (Early Miocene) successions of the Güvem Basin (NW Central Anatoia, Turkey) has been carried out with the aim of reconstructing the palaeovegetation. The pollen spectra indicate a flora dominated by trees such as Quercus deciduous type, Carya, Carpinus, Ulmus/Zelkova, Engelhardia, Quercus ilex type and Pinaceae. Pterocarya, Juglans, Alnus, Salix, Liquidambar and Oleaceae are represented by lower percentages. Herbs and shrubs are represented by minor amounts of Poaceae, Amaranthaceae/Chenopodiaceae, Asteraceae/Asteroideae, Brassicaceae, and the aquatics Potamogeton, Sparganium and Typha. The Burdigalian flora reflects a mixed mesophytic forest with Quercus deciduous type, Quercus ilex type, pine species, Ulmus/Zelkova, Engelhardia, Carya, Carpinus, Pterocarya, etc., sparcely interspersed with open herbaceous areas. This flora reflects a warm-temperate climate. The fluctuations in abundances of broadleaved trees and xerophytes may represent fluctuations of relatively wet and dry periods. The overall composition of the flora of the Güvem Basin reflects cooler conditions compared with other Early Miocene floras in Europe, which is possibly due to intense volcanic activity of the area.

Miocene floras in the Daigo area, Ibaraki Prefecture

Miocene floras in the Daigo area, Ibaraki Prefecture

Correlation of Miocene floras of the climatic optimum in the Far East

Based on interregional correlation of geological and paleogeographic events, a new approach has actively been developed in the past few decades. One such Cenozoic significant event in the Russian Far East is the Miocene Climatic Optimum, which designates a temperature increase after a prolonged climatic depression in the second half of the Oligocene–initial Miocene and reached its maximum at the Early–Middle Miocene transitional interval. This paleoclimatic event is of planetary importance [1]. It was recorded on paleoclimatic curves based on study of the isotopic composition of carbonates of marine fossils [2]. Terrestrial plants are known to be sensitive indicators of climatic changes. Therefore, they can be used not only for paleoclimatic reconstructions, but also for the stratigraphic correlation of sedimentary sequences of spatially distant regions as well. It is especially important for the southern region of the Russian Far East where Tertiary deposits are mainly represented by continental facies.

Floristic turnover in Iceland from 15 to 6 Ma – extracting biogeographical signals from fossil floral assemblages

AbstractAim This study aims to document the floristic changes that occurred in Iceland between 15 and 6 Ma and to establish the dispersal mechanisms for the plant taxa encountered. Using changing patterns of dispersal, two factors controlling floristic changes are tested. Possible factors are (1) climate change, and (2) the changing biogeography of Iceland over the time interval studied; that is, the presence or absence of a Miocene North Atlantic Land Bridge.Location The North Atlantic.Methods Species lists of fossil plants from Iceland in the time period 15 to 6 Ma were compiled using published data and new data. Closest living analogues were used to establish dispersal properties for the fossil taxa. Dispersal mechanisms of fossil plants were then used to reconstruct how Iceland was colonized during various periods.Results Miocene floras of Iceland (15–6 Ma) show relatively high floristic turnover from the oldest floras towards the youngest; and few taxa from the oldest floras persist in the younger floras. The frequencies of the various dispersal mechanisms seen in the 15‐Ma floras are quite different from those recorded in the 6‐Ma floras, and there is a gradual change in the prevailing mode of dispersal from short‐distance anemochory and dyschory to long‐distance anemochory. Two mechanisms can be used to explain changing floral composition: (1) climate change, and (2) the interaction between the dispersal mechanisms of plants and the increasing isolation of proto‐Iceland during the Miocene.Main conclusions Dispersal mechanisms can be used to extract palaeogeographic signals from fossil floras. The composition of floras and dispersal mechanisms indicate that Iceland was connected both to Greenland and to Europe in the early Middle Miocene, allowing transcontinental migration. The change in prevalence of dispersal modes from 15 to 6 Ma appears to reflect the break‐up of a land bridge and the increasing isolation of Iceland after 12 Ma. Concurrent gradual cooling and isolation caused changes in species composition. Specifically, the widening of the North Atlantic Ocean prevented taxa with limited dispersal capability from colonizing Iceland, while climate cooling led to the extinction of thermophilous taxa.

The spread of grass-dominated habitats in Turkey and surrounding areas during the Cenozoic: Phytolith evidence

The arrival of hipparionine horses in the eastern Mediterranean region around 11 Ma was traditionally thought to mark the simultaneous westward expansion of savanna vegetation across Eurasia. However, recent paleoecological reconstructions based on tooth wear, carbon isotopes, and functional morphology indicate that grasses played a minor role in Late Miocene ecosystems of the eastern Mediterranean, which were more likely dry woodlands or forests. The scarcity of grass macrofossils and pollen in Miocene floras of Europe and Asia Minor has been used to support this interpretation. Based on the combined evidence, it has therefore been suggested that Late Miocene ungulate faunal change in the eastern Mediterranean signals increased aridity and landscape openness, but not necessarily the development of grass-dominated habitats. To shed new light on the Miocene evolution of eastern Mediterranean ecosystems, we used phytolith assemblages preserved in direct association with faunas as a proxy for paleovegetation structure (grassland vs. forest). We extracted phytoliths and other biogenic silica from sediment samples from well-known Early to Late Miocene (∼ 20–7 Ma) faunal localities in Greece, Turkey, and Iran. In addition, a Middle Eocene sample from Turkey yielded phytoliths and served as a baseline comparison for vegetation inference. Phytolith analysis showed that the Middle Eocene assemblage consists of abundant grass phytoliths (grass silica short cells) interpreted as deriving from bambusoid grasses, as well as diverse forest indicator phytoliths from dicotyledonous angiosperms and palms, pointing to the presence of a woodland or forest with abundant bamboos. In contrast, the Miocene assemblages are dominated by diverse silica short cells typical of pooid open-habitat grasses. Forest indicator phytoliths are also present, but are rare in the Late Miocene (9–7 Ma) assemblages. Our analysis of the Miocene grass community composition is consistent with evidence from stable carbon isotopes from paleosols and ungulate tooth enamel, showing that C 4 grasses were rare in the Mediterranean throughout the Miocene. These data indicate that relatively open habitats had become common in Turkey and surrounding areas by at least the Early Miocene (∼ 20 Ma), > 7 million years before hipparionine horses reached Europe and arid conditions ensued, as judged by faunal data.