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The recent discovery of diverse fossil flowers and floral organs in Cretaceous strata has revealed astonishing details about the structural and systematic diversity of early angiosperms. Exploring the rich fossil record that has accumulated over the last three decades, this is a unique study of the evolutionary history of flowering plants from their earliest phases in obscurity to their dominance in modern vegetation. The discussion provides comprehensive biological and geological background information, before moving on to summarise the fossil record in detail. Including previously unpublished results based on research into Early and Late Cretaceous fossil floras from Europe and North America, the authors draw on direct palaeontological evidence of the pattern of angiosperm evolution through time. Synthesising palaeobotanical data with information from living plants, this unique book explores the latest research in the field, highlighting connections with phylogenetic systematics, structure and the biology of extant angiosperms.

The global extent and distribution of forest trees is central to our understanding of the terrestrial biosphere. We provide the first spatially continuous map of forest tree density at a global scale. This map reveals that the global number of trees is approximately 3.04 trillion, an order of magnitude higher than the previous estimate. Of these trees, approximately 1.39 trillion exist in tropical and subtropical forests, with 0.74 trillion in boreal regions and 0.61 trillion in temperate regions. Biome-level trends in tree density demonstrate the importance of climate and topography in controlling local tree densities at finer scales, as well as the overwhelming effect of humans across most of the world. Based on our projected tree densities, we estimate that over 15 billion trees are cut down each year, and the global number of trees has fallen by approximately 46% since the start of human civilization.

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The Siluro-Devonian primary radiation of land biotas is the terrestrial equivalent of the much-debated Cambrian "explosion" of marine faunas. Both show the hallmarks of novelty radiations (phenotypic diversity increases much more rapidly than species diversity across an ecologically undersaturated and thus low-competition landscape), and both ended with the formation of evolutionary and ecological frameworks analogous to those of modem ecosystems. Profound improvements in understanding early land plant evolution reflect recent liberations from several research constraints: Cladistic techniques plus DNA sequence data from extant relatives have prompted revolutionary reinterpretations of land plant phylogeny, and thus of systematics and character-state acquisition patterns. Biomechanical and physiological experimental techniques developed for extant 263 0066-4162/98/1120-0263$08.00 264 BATEMAN ET AL plants have been extrapolated to fossil species, with interpretations both aided and complicated by the recent knowledge that global landmass positions, currents, climates, and atmospheric compositions have been profoundly variable (and thus nonuniformitarian) through the Phanerozoic. Combining phylogenetic and paleoecological data offers potential insights into the identity and function of key innovations, though current evidence suggests the importance of accumulating within lineages a critical mass of phenotypic character. Challenges to further progress include the lack of sequence data and paucity of phenotypic features among the early land plant clades, and a fossil record still inadequate to date accurately certain crucial evolutionary and ecological events.

AlSSTKACT have been discovered within the past 15 to 20 years. These floras are particularly abundant in I p per Cretaceous sediments and have been reported from widely sepaiate geographic regions in the Northern Hemisphere. The first comprehensive studies were based on European material, and rich Lite Cretaceous floras are known from Cenomanian to Maastrichtian strata of the Czech Republic. Germanv. \ustria, the Netherlands, Portugal, and S\eden (

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