The Miocene is characterized by a series of key climatic events that led to the founding of the late Cenozoic icehouse mode and the dawn of modern biota. The processes that caused these developments, and particularly the role of atmospheric CO 2 as a forcing factor, are poorly understood. Here we present a CO 2 record based on stomatal frequency data from multiple tree species. Our data show striking CO 2 fluctuations of Ϸ600 -300 parts per million by volume (ppmv). Periods of low CO 2 are contemporaneous with major glaciations, whereas elevated CO 2 of 500 ppmv coincides with the climatic optimum in the Miocene. Our data point to a long-term coupling between atmospheric CO 2 and climate. Major changes in Miocene terrestrial ecosystems, such as the expansion of grasslands and radiations among terrestrial herbivores such as horses, can be linked to these marked fluctuations in CO 2.atmospheric CO2 ͉ fossil plants ͉ paleoclimates ͉ stomata ͉ C4 plants T he Miocene is distinguished by extreme climatic optima alternating with major long-term climatic cooling, which together mark the founding of the modern late Cenozoic cold mode and the evolution of modern terrestrial biomes (1). Grass-dominated ecosystems became established in the low and middle latitudes of many parts of the world, such as North America, Eurasia, Africa, and Australia (2). Major radiations in large mammalian herbivores have been attributed to changes in the distribution of vegetation and terrestrial primary productivity (3-5). A significant change in dental morphology from lowto high-crowned toothed horses occurs during the middle Miocene, whereas a transition from a C 3 plant to C 4 plant diet did not take place before the late Miocene (6).Both Cenozoic climate trends and changes in terrestrial ecosystems have been thought to be influenced by long-term CO 2 fluctuations (6-8). Before marine pCO 2 proxy records were available, Cenozoic CO 2 trends were inferred from carbonisotope records of paleosols (9) and from carbon cycling models (10), which indicated a long-term decrease from Ϸ1,000 to Ͻ500 parts per million by volume (ppmv) throughout the Cenozoic. Approximately a decade later, CO 2 reconstructions based on marine geochemical proxies indicated consistently low late Pleistocene (glacial-like) CO 2 values of Ϸ200-280 ppmv (11, 12). Consequently, the Miocene has been regarded as a geological period in which climate and the carbon cycle were essentially decoupled. Because of this alleged decoupling, the role of atmospheric CO 2 as a climate forcing factor has been disputed (13-15). However, a permanently low CO 2 scenario has been challenged because photosynthetic models predict that plant life would not have thrived under such conditions (16). Climate models showed the importance of atmospheric CO 2 as a fundamental boundary condition for Cenozoic climate change (17). In fact, a coupling between atmospheric CO 2 and glacialinterglacial cycles over the past 600,000 years is well documented by ice core analysis (18). Understanding the long-term ...

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A large number of plant macrofossils from several Middle to Upper Miocene localities from Iceland have been studied. The fossil material includes four ferns and fern allies, seven conifers, and about 40 species of flowering plants. Betula islandica and Salix gruberi are described as new species. Coniferous twigs previously ascribed to the genus Sequoia are shown to belong to Cryptomeria based on macro‐morphological and epidermal features. Fossil plants from Iceland are compared with coeval fossil taxa from Europe and North America and with living plants. The main finding is that the Miocene flora of Iceland belongs to a widespread Neogene northern hemispheric floral type including plants whose representatives are restricted to East Asia, North America and to western Eurasia at the present time. Previously inferred conspicuous similarities to North American modern equivalents appear to be misleading. The type of vegetation in four plant‐bearing sedimentary formations from the late Mid Miocene to Late Miocene, the 12 Ma Brjánslækur‐Seljá Formation, the 10 Ma Tröllatunga‐Gautshamar Formation, the 9–8 Ma Skarðsströnd‐Mókollsdalur Formation, and the 7–6 Ma Hreðavatn‐Stafholt Formation, corresponds to a humid temperate broadleaved (deciduous)–coniferous mixed forest dominated by Betulaceae, Fagaceae and Acer. Changes in species composition in the sedimentary formations reflect a shift from warm temperate (Cfa climate) to cool temperate (Cfb climate) conditions from the late Mid Miocene to the latest Miocene. This shift was connected to repeated phases of extinction and colonization. Specifically, one set of thermophilic taxa including Magnolia, Liriodendron, Sassafras and Comptonia went extinct between 12 and 10 Ma, and appears to have been replaced by another set of thermophilic taxa in the 10 Ma formation (Juglandaceae aff. Pterocarya/Cyclocarya, Rhododendron ponticum type). The 9–8 and 7–6 Ma formations are characterized by taxa that migrated to Iceland from Europe, such as Fagus gussonii, Betula cristata and Pterocarya fraxinifolia type. Although there is convincing evidence that plants colonized Iceland both from North America and Europe until 12 Ma, migration in the younger formations (9–8, 7–6 Ma) is suggested to have occurred mainly from Europe. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2005, 149, 369–417.

The 4°K_4°Ar radiometric whole-rock analyses of a series of samples mainly from lava flows intercalated between the fossiliferous sediments of several sites of the C eske Stredohoff Mountains (Northern Bohemia) has made possible to get results generally ranging between 38.3 ± 0.9 Ma and 23.7 ± 1.3 Ma. They mostly characterize Oligocene ages and, more precisely, the Stampian. They are parallelized with informations provided both by the flora and the lower vertebrate fauna (mainly the fish-fauna) of the studied fossiliferous localities.

An attempt is made to follow the extent of forest types during the Palaeocene and Eocene in time and space over Europe. Problems that hinder producing more detailed maps of potential Eocene vegetation are the different palaeogeographic configuration of land and sea and changing relief due to orogeny, the variation in global climate, atmospheric circulation and the world ocean. The early Palaeogene palaeofloristic sites in Europe are widely spaced and the data so far obtained are of varying quality from one site to another. The differences between zonal, intrazonal (azonal) and extrazonal formations and impact of precipitation must be considered. Objective definitions of units based on diversity percentages of components are still to be elaborated. The macropalaeobotanical data thus far available allow us to distinguish intuitively three zonal vegetation types: 1) Broad-leaved evergreen/semi-evergreen quasi-paratropical forest with a high diversity of woody angiosperms related to tropical families, ferns and a low diversity of conifers (mostly Doliostrobus), 2) Broad-leaved nothophyllous evergreen forest with evergreen Fagaceae, Lauraceae, Altingiaceae, Myrtaceae and some conifers (Pinus, Doliostrobus, Cephalotaxus) and 3) Polar deciduous to mixed mesophytic forest with well diversified angiosperms predominantly deciduous and moderate representation of Ginkgo, conifers and ferns. Intrazonal (azonal) formations include riparian gallery forests, coal-forming swamp forests, and poorly developed mangroves with marginal freshwater wetland/aquatic vegetation. The Eocene extrazonal vegetation is less distinct in Europe, consisting probably of pine forests in high mountains and lowland sclerophyllous scrub on specific substrates. •

Tertiary floras occurring in the Bohemian Massif based on plant macrofossils (leaves and carpological material) are reviewed. The sites are situated in various stratigraphical levels of the Cheb, Sokolov, Most, Zittau, České Budějovice and Třeboň basins, volcanic complexes of the Doupovské hory Mts and České středohoří Mts, as well as in Tertiary fluvial sedimentary relicts scattered near Plzeň, Prague and elsewhere in the western part of the Czech Republic. The overview focuses on floristic and phytostratigraphical characteristics of the defined lithostratigraphical units and their dating within the Bohemian Massif and correlation with previously defined paleofloristic units (Floristic Assemblages i.e., "Florenkomplexe") of Boreal and Central Europe. New palaeoclimatical datasets obtained using the leaf physiognomy (CLAMP), co-existence (CA) and ecophysiological methodologies show vegetation and palaeoclimatic evolution during the Tertiary in the studied area.•