abstract

About 30 specimens of petrified fossil woods were selected which were collected from the three localities i.e. Ranikot fort area, Rehmam Dhoro and Thanobulla Khan, district Jamshoro, Sindh, Pakistan. The following 12 species could be identified as the new species from this locality viz. Anogeisussoxylon ranikotensis sp. nov., Anogeisussoxylon rehmanense sp. nov., Terminalioxylon ranikotensis sp. nov. (family Combretaceae), Diptercarpoxylon ranikotensis sp. nov. (family Dipterocarpiaceae), Laurinoxylon ranikotensis sp. nov. (family Lauraceae), Caryeoxylon ranikotensis (family Lecythidaceae), Albizinium ranikotensis sp. nov., Cynometroxylon sindensis sp nov., Pahudioxylon ranikotensis sp. nov., Pahudioxylon sindensis sp. nov., (Leguminoseae), Lagerstroemioxylon thanobolensis sp nov. (family Lythraceae) and Euphorioxylon ranikotensis sp. nov. (family Sapindaceae), occurring in Sindh are fully described and identified, one new combination have been developed. Every specimen is provided with complete anatomical description, diagnosis and discussion which include the affinities and relationship with living and fossil woods.

For all the fossil woods the standard techniques were used for the preparation of three dimensional sections. The photographs were taken with compound microscope and camera lucida drawings are provided for each species.

Biogeography of the fossil wood was discussed and it has been suggested that the fossilized plants were not originated in the study area but were transported from somewhere else. The size of the fossils indicates that source area was not far from the present study area.

The absence of growth ring and presence of diffuse porous wood character in the fossil woods under investigation indicates the tropical climatic condition in the source area. Most of the living counter parts of these fossil taxa confirm the above distribution.

The taphonomic processes are indicating the traumatic necrology and allochthonous assemblages in biostratnomy before burial. Diagenesis is indicating that wood remains were deposited in near-shore marine environments where silica-rich sediments were weathering.

CALIBRATING ATMOSPHERIC CO2 CHANGES WITH THE CUTICLE DATABASE
Richard S. Barclay¹, David L. Dilcher², Jennifer C. McElwain³, Bradley B. Sageman¹

¹Northwestern University, Evanston, Illinois, 60208, USA
²Florida Museum of Natural History, Gainesville, Florida, 32611, USA
³Field Museum of Natural History, Chicago, Illinois, 60605, USA

Plant cuticle has been underutilized as a tool in the identification of both modern and fossil plant species. Cuticle preserves the spatial arrangement of epidermal features such as stomatal complexes, trichomes, and glands. Suites of these characters can be taxonomically distinctive but have not been widely applied in recent studies of both modern and fossil plants. Since characteristics of modern cuticle are often preserved on fossil specimens, this provides another useful tool for determining the phylogenetic relationships of fossil plants. To increase the application of plant cuticle for comparison of fossil and modern material, we are developing a database of modern cuticle that botanists and paleobotanists can access for free via the Internet. The Cuticle Database utilizes the collection of modern cuticle slides of herbarium specimens prepared by David Dilcher, stored in the collections at the Florida Museum of Natural History. The collection contains preparations from over 290 plant families, predominantly of dicotyledonous angiosperms. When the first phase is complete, the Cuticle Database will display images of the abaxial and adaxial leaf surfaces from over 2,000 species of plants from the collections. The Cuticle Database uses freeware software designed to compare modern cuticle with fossil cuticle using the same cuticular characteristics. The database can be reached at this URL: http://patroklos.earth.northwestern.edu/~richbarclay/webpages/home.html.
The Cuticle Database is presently being used to study the Cenomanian-Turonian (C-T) boundary to create a link between the atmosphere-marine system. The C-T boundary is marked by a second order marine extinction associated with an oceanic anoxic event known as OAEII. The rapid deposition of organic carbon at the onset of the event is hypothesized to have significantly drawn down pCO2 causing a temporary cooling of climate. Fossil cuticle has been collected from near-shore marine and terrestrial deposits through the OAEII interval in southwestern Utah in order to estimate pCO2 through the event. This project uses the inverse relationship of stomatal index to CO2 levels in order to estimate the change of pCO2 at the onset of OAEII. However, since the response of plants to changes in pCO2 is taxon specific the fossil material needs to be constrained. This project will use the modern species in the Cuticle Database to help constrain the taxonomic identity of the fossil material so that a nearest living relative can be used to calibrate the magnitude of pCO2 change. Angiosperms and conifers dominate the abundance of cuticle present in the section, with lesser representation by potential ginkgophytes and bennettites. Initial study of the angiosperm fossil cuticle suggests affinities to the Lauraceae. Further analysis of modern species in the Cuticle Database will help to determine if the fossil material can be reliably constrained to genera within this family.

Florida Museum of Natural History, University of Florida, Gainesville, FL 32611-7800, USA

Scenarios proposed to explain the origin of crown-group primates (Euprimates) include adaptation for: (1) nocturnal visual predation of insects in an arboreal setting, which predicts simultaneous evolution of forward-facing orbits, grasping, and a shift in diet towards increasing insectivory; (2) grasp-leaping locomotion between branches of trees, which predicts simultaneous evolution of grasping and leaping; and (3) access to fruit, flowers and insects in terminal branches, which predicts simultaneous evolution of grasping and a shift in diet towards increasing omnivory. Only the fossil record, which records the order of acquisition of key adaptive traits, can provide a direct test of these competing hypotheses. Cladistic analyses indicate that late Paleocene-early Eocene "plesiadapiforms" are stem primates, with a closer relationship to Euprimates than other euarchontan groups including treeshrews (Scandentia) and flying lemurs (Dermoptera). The divergence of Primates (sensu lato) from other euarchontans likely occurred prior to the K-T boundary (65 Mya). Plesiadapiforms diverged from a more insectivorous, arboreal, euarchontan ancestor into an adaptive landscape newly forming at this time by the radiation of angiosperms and their potential food products. Even the earliest plesiadapiforms are differentiated from insectivores by lower crowned molars, indicating increased exploitation of fruits, flowers, and exudates. Acquisition of grasping hands and feet (~62 Mya) would have allowed easy access to terminal branches where fruits and flowers are found. Euprimates first appear, together with the oldest perissodactyls (odd-toed ungulates) and artiodactyls (even-toed ungulates), during the Paleocene-Eocene Thermal Maximum (~55 Mya) coincident with rapid global warming of 4-8°C over a period of 10-20 ky and a major shift in floral composition. These first Euprimates differ from plesiadapiforms in having features indicative of specialized leaping and convergent orbits that are relatively larger and more forward facing. These features could indicate a shift to visually directed predation and/or a change in locomotor mode to include grasp-leaping on small diameter supports. The former explanation is weakened by the inferred omnivorous or herbivorous habits of many early euprimates (even those of small body size), and the concomitant lack of evidence for a clear transition to more effective predation and greater insectivory at the euprimate node. Both the visual predation and grasp-leaping hypotheses are weakened by the recent discovery of a divergent big-toe (hallux) bearing a flattened nail in the omnivorous plesiadapoid Carpolestes simpsoni, which lacks leaping features and convergent orbits, suggesting that grasping arose independently of visual specializations and leaping in primate evolution. The sequence of characters added in early primate evolution is supportive of the hypothesis that primates acquired their suite of features by "diffuse co-evolution" with angiosperms through the Paleocene and suggests that a diversification of angiosperm fruit-types at this time might have been central to shaping the origin of the group.

Foliar Physiognomy & Taphonomy: Keys to Unlocking Australia’s Fossil Rainforests

Taxonomic studies allow broad inferences about the regional composition of fossil vegetation, but both local and climatic interpretations are dependent on a complete understanding of the taphonomy and foliar physiognomy of the flora. Studies of this sort should occur after those on analogous extant vegetation have been completed. Here we report selected results from three studies undertaken in Australia’s tropical rainforest on Mt Lewis and on Emerald Creek in northern Queensland. Our overall aims were to analyze the effects of localized altitudinal gradients on the physiognomic signature of leaf beds, to examine relative sample size required for both physiognomic and floristic studies, and also to explore the effects of varying leaf morphotypes on their movement in a rainforest stream. In the first study, leaf litter and selected tree and vine specimens from an altitudinal gradient of 570m were collected and analysed for various physiognomic parameters. Results revealed that while no pattern emerged across the gradient for margin type or species number, leaf length in the litter did decrease significantly with increasing altitude. The high time expenditure on the first project prompted a series of taphonomic studies at CSIRO site EP18 on Mt Lewis to examine sample size. This study demonstrated that random litter samples taken across a half-hectare plot did not yield significant differences in either physiognomic profile or species number. Similarly no difference was recorded whether one meter square samples were collected and counted or 0.25 square meter samples were used. Preliminary results from the third study, conducted at Emerald Creek have confirmed that large and lobed leaves don’t travel as well in sub-aqueous environments compared to smaller, more streamlined leaves. However, we have also observed that both flexibility and thinness of cuticle can affect the predicted results based on size and shape. In particular, an example of this is Melastoma affine D. Don, whose leaves travel far shorter distances than predicted by size and shape parameters.

Department of Geology
Royal Holloway University of London
Egham, Surrey, TW20 0EX, UK

This presentation will briefly outline three aspects of current research on ancient wetland plants and the fossil plant assemblages to which they belong.

The first aspect concerns the genus Regnellidium, an extant aquatic heterosporous fern (Marsileaceae) with a single species in Southern Brazil and Argentina. Dorofeev (1981, Bot.Zh.66,792-801) described three species of fossil Regnellidium based on dispersed megaspores from the Eocene and Oligocene of former USSR. One species also occurs in the German Oligocene (Mai & Walther 1978). Attached microspores were noted, but not described, by Dorofeev. Dispersed megaspores of Molaspora lobata (Dijkstra) Hall are widespread in the late Cretaceous and also occur in the earliest Paleocene. They are considered ‘almost identical to’ Regnellidium an affinity supported by fossil sporocarps containing megaspores and microspores (Lupia et al 2000, Int.J.Plant Sci,161,975-988). Specimens of the three species described by Dorofeev have been studied using scanning and transmission electron microscopy. Results are being used to consider if the Eocene & Oligocene Regnellidium and the late Cretaceous to Paleocene Molaspora lobata represent the same taxon; if the fossils should be assigned to the modern genus Regnellidium and implications for the evolution and palaeobiogeography of Regnellidium

The second aspect concerns the Insect Limestone, a richly fossiliferous, bed within the Bembridge Marls Member of the Bouldnor Formation, Solent Group, of earliest Oligocene age. The Insect Limestone flora is distinctive amongst British late Paleogene floras due to preservation of leaves and winged or plumed fruits and seeds from trees, alongside the more ubiquitous marshland and aquatic elements well known from this time interval. A revision of the flora is being undertaken (in collaboration with Peta Hayes). Of particular interest are the Acrostichum and Azolla and their association with putative ‘arid’ elements. When combined with the insect revision (led by Andrew Ross) this work will provide an exceptional window on a continental community that existed just prior to the onset of the Oi-1 glaciation that marks a global transition from a greenhouse to an icehouse world.

The third aspect concerns Azolla from the Cretaceous – Paleogene boundary at Teapot Dome, Wyoming, USA. This site yields large numbers of unseparated Azolla soral clusters, especially containing mature microspore massulae. Some unseparated pollen tetrads and partial anther contents are also found. Renewed interest in these occurrences has been stimulated from the hypothesis that unseparated spore tetrads at the Permo-Triassic boundary may be linked to environmental mutagenesis during that ecological crisis. (Visscher et al 2004, PNAS 101,12952-12956).

Thanks to Zlatko Kvacek for Russian translation; Olga Arbuzova, Lena Golovneva & Jan Wojcicki for fossil loan; Tony Brain for help with EM; Alison Paul (NHM) for loan of modern Regnellidium, David Batten for collaboration on Molaspora and INTAS for funding to a team led by Andrew Ross for the Insect Limestone Project. Special thanks to Jack Wolfe for his collaboration on the Teapot Dome project and to David Dilcher for his interest in my work on wetland floras since my postgraduate days.

In 1975 the discipline of angiosperm paleobotany was largely focused on improving accuracy and credibility. In the USA, leaf studies were prominent and led by David Dilcher and Jack Wolfe along with Leo Hickey. Angiosperm palynology was reaching its potential through studies by Gil Brenner and Jim Doyle, while studies of fruits and seeds, done so well historically by Reid and Chandler, were about to experience a renaissance through the works of Margaret Collinson and Bruce Tiffney. Historically, reports of fossil flowers were very rare despite their potential systematic and ecological implications related to timing, potential for phylogenetically informative mosaicism and relevance to the history of important aspects of angiosperm reproductive biology. Sustained modern era investigations of flower fossils began in David Dilcher's lab in 1973 (and were first published in Science in 1975). These were focused on Eocene fossils from the Paris area. In contrast with what had been a gestalt approach to determining affinities of angiosperm fossils previously, there was now a strong emphasis on careful description of difficult fossil material, determination of characters followed by, essentially, a phenetic assessment of affinities through comparisons of what were deemed to be sets of taxonomically informative characters. And this approach was applied to early studies of flowers. While the only option at the time (and of course the one practiced by myself as well as by others), such an approach was a naïve and imprecise method for assessing the affinities of fossil flowers. Of course, phylogenetic context was then unavailable for fossils or even for the extant angiosperms. Thus, the informative potential of the flower, and even of the entire angiosperm fossil record could not be fully realized outside of a very subjective framework. Subsequently, important methodological developments and exciting new fossil discoveries coincided with dramatic implications for angiosperm paleobotany and systematics. First, phylogenetics, gaining momentum through the pioneering work of Wagner, Fitch, Farris and then Swafford, came into use in studies of plants through early work by Parenti, Hill and Crane. Rapidly multiplying applications of phylogenetic methodology to plants (as in studies by Donoghue, Doyle, Loconte, Nixon, Rothwell, Stevenson, and Serbet, among others) led inevitably to the use of phylogenetic context in identifying fossil flowers. At first phylogenetic context fossil flower identifications were accomplished through analyses of morphological data matrices and then, in view the impact of missing characters in such analyses, as addressed by Nixon, through inclusion of fossils in large combined data sets made feasible through new powerful software developed by Goloboff and Nixon. Second, Cretaceous compression flower fossils became available for study from Kansas USA (in the Dilcher Laboratory), while charcoalified fossil flowers, with numerous characters and remarkable preservation were first reported by Tiffney from Martha's Vineyard USA and shortly after by Skarby and Friis from southern Sweden. These were soon followed by numerous reports of similarly preserved flowers by Friis, Crane and Pedersen and others (from North Carolina and Georgia USA, and Portugal), and of Turonian angiosperms from the Perth Amboy region of New Jersey, USA by Gandolfo, Nixon and myself. These investigations further increased our understanding of angiosperm history and timing in angiosperm evolution as did similarly burgeoning reports of Tertiary fossil flowers by numerous authors including Daghlian, Herendeen, Manchester, Stockey, Taylor, and Zavada. Yet, various analyses of nucleic acid sequence data through models, especially those of Sanderson, have provided independent assessments of timing in angiosperm history. And these divergent, although sometimes complementary, methodologies have occasionally produced conflicting results. Conflict is not restricted to understanding timing. It even persists in determining affinities of certain key fossils (and thus in patterns of relationship among fossil taxa) in spite of (or perhaps because of) the availability of phylogenetic context due to differences in character selection and/or homology assessment. However, the fact that we have extensive data and the analytical methods that have led to these conflicts is encouraging. The prospect of resolving such conflicts is exciting and studies (including discovery) leading to such resolutions will play an important role in characterizing the future of paleobotanical studies and their value in illuminating various aspects of the history of angiosperm evolution. Throughout the past 30 + years, David's laboratory has been a crossroads for important events in studies of fossil angiosperm flowers and their implications as illustrated by the list of people who worked in his laboratory, partially noted above, who spent rewarding and enjoyable time there and who, like myself, benefited from his generosity.

Leaves and fruits of Ulmus from the Early-Middle Eocene of British Columbia and Washington are assigned to two species. Ulmus okanaganensis sp. nov. is based on leaves attached to flowering and fruiting twigs and isolated leaves and fruits. Leaves display a polymorphism ranging from large leaves with compound teeth with blunt apex to small ones with simple teeth resembling Zelkova. In extant Ulmus, sucker shoot leaves, elongation shoot leaves, and leaves on short annual branches often display a very similar polymorphism. In the fossil, flowers are arranged in fascicles having short pedicels. Fascicles are formed in the axils of leaves of current year shoots and appear together with the leaves. This is uncommon in modern species of Ulmus where leaves either appear in spring on shoots of the previous year, or in autumn in axils of leaves of current year shoots. Fruits of U. okanaganensis are samaras with extremely reduced or absent wings. Unwinged fruits of modern Ulmus are typically ciliate along the margin of the endocarp and the persistent styles but only a single fruit of U. okanaganensis has been found preserving hairs. The small, shallowly lobed perianth is situated below the endocarp. A second type of foliage is assigned to U. chuchuanus LaMotte. This foliage is wider than that of U. okanaganensis and has more densely spaced secondary veins. It also has characteristic compound teeth with primary and subsidiary teeth displaying conspicuously different orientations. Leaves of U. chuchuanus co-occur with a second type of fruit but have not been found in attachment. These fruits are larger than in U. okanaganensis, with a narrow wing, persistent styles, and a large and wide persistent perianth that tapers abruptly into the perianth tube.

Stable carbon isotope analyses of fossil tooth enamel of herbivorous mammals can help reconstruct past environments and identify the presence of dense forest canopies. Stable carbon isotopes are incorporated into the tooth enamel of fossil taxa, retaining a dietary isotopic signal that is reflective of plants consumed. Since floral δ¹³C values decline with increasing canopy density, δ¹³C values can be used to reconstruct canopy density due to greater ¹³C discrimination occurring in dense closed canopy forests as compared to more open C₃ environments. Despite the complexity of factors contributing to δ¹³C values in C₃ forests, variation is systematic. Fossil tooth enamel δ¹³C values can therefore detect meaningful differences in habitat type that can assist in determining relative canopy density.

Fossil tapirs are likely indicators of forested floral communities. Extant tapirs are highly conservative in dietary and migratory behavior, and typically inhabit the densest canopy habitats available. Stable isotope values of extant and fossil tapirs consistently support their morphological classification as low-crowned browsers. Additionally, the home ranges of extant tapirs are relatively consistent throughout the year; therefore, differences in stable isotope values are likely a result of environmental variation and not migration. Dietary variation within a population of the extant tapir Tapirus bairdii is minimal; the total range of δ¹³C enamel values from late erupting adult teeth is less than 3.5‰. Consequently, tapirs are model organisms for identifying forested habitats and determining relative canopy density in space and time.

The presence of low-crowned tapirs can initially assist in identification of forest flora; however, isotopic analysis of the remaining herbivorous mammals within an ancient fauna will assist in determining the environmental heterogeneity of a fossil locality. The Gray Fossil Site, biostratigraphically dated between 4.5 and 7 million years ago, contains the highest known concentration of Neogene tapirs and a unique combination of taxa with Eurasian ancestry, including: the tapir Tapirus polkensis, rhino Teleoceras cf. T. hicksi, camel cf. Megatylopus sp., peccary Tayassuidae, and proboscidean Gomphotheriidae. Due to the rarity of late Cenozoic fossil sites in eastern North America and the ideal nature of fossil tapirs for such analyses, the Gray site can clarify paleoecological phenomenon during the Neogene. Based on stable isotope analyses, Tapirus polkensis is identified as a hyperbrowser that inhabited dense, closed canopy environments. Teleoceras sp., despite being morphologically presumed grazers, yields stable carbon isotope data (-13.2‰) suggesting their presence as forest dwelling browsers. Since palynological data demonstrates negligible amounts of grass pollen, Teleoceras sp. are further presumed to be browsers as opposed to mixed feeders/C₃ grazers. The camel and peccary are also identified as forest-dwelling browsers with average δ¹³C values of -13.8‰ and -13.1‰, respectively. The total range of δ¹³C_enamel values indicates the presence of a C₃ dominated floral environment. Additionally, the presence of temperate fossil pollen constrains environmental reconstructions identifying the ancient forests from the Gray site as relatively dense. Carbon and oxygen serial sample variation of the tapir, rhino, peccary, and proboscidean is less than 1.5‰, suggesting little difference in seasonal temperature and/or precipitation. These data support the presence of North American forest refugia in the southern Appalachians during the Neogene.

Creating a realistic view into a rich and complex Greenland Late Triassic landscape involves multi-layered process. How do the scientist and artist work together to create an accurate and natural appearing scene? How are artistic considerations such as design and color handled to satisfy the needs of the scientist? It all begins with an appropriate landform as described by a sedimentologist and moves on to incorporate fossils (data includes precise numbers of species for the given area illustrated), modern models of plants and ecosystems. Guided by paleobotanist Jenny McElwain, the scientific illustrator draws from fossils, extrapolates and eventually constructs three-dimensional models. Jenny examines cuticle detail for clues to color, texture and reflectivity; sediments provide other leads to the landscape’s appearance, from the placement of plants to the color of the water. The artist also paints many field studies of appropriate modern landscapes and plants to become intimately familiar with applicable growth patterns, perspective and lighting.

In 1975, Leo Hickey and Jack Wolfe (Ann. Missouri Bot. Gard 62: 538-589) published the first and only comprehensive survey of the diversity of leaf architecture in angiosperms ("dicots"), using the Takhtajan and Cronquist systems as a framework for evaluating the systematic value and evolution of leaf characters. Examination of their results in the context of increasingly robust molecular phylogenies reveals many cases in which leaf architecture is more consistent with molecular trees (codified in the APG system) than with the Takhtajan-Cronquist systems. Rooting of the angiosperms among "ANITA" taxa confirms the view of Hickey & Wolfe that angiosperms originally had pinnate venation, but ovate leaf form, rather than elliptical-obovate as in Magnoliales, and no stipules. Chloranthoid teeth may be homologous in Chloranthaceae and basal eudicots (Ranunculales, Trochodendrales), but probably as a symplesiomorphy shared with more basal lines (Amborella, Trimenia, Schisandraceae) rather than a synapomorphy. Palmate venation was derived from pinnate more than once (an isolated case being near-basal Nymphaeales), but fewer times than Hickey & Wolfe assumed, since Aristolochiaceae and former Piperales form a clade (Piperales sensu APG). Given the nested position of Canellales (including Winteraceae), Magnoliales, and Laurales, their basically pinnate venation and entire margins are probably secondarily derived rather than primitive.

Molecular trees imply that eudicots, which Takhtajan and Cronquist thought were polyphyletic but are now strongly supported as a clade, originally had palmately veined leaves, as Hickey & Wolfe proposed for Rosidae and Hamamelidae, becoming ternately dissected in Ranunculales. Hickey & Wolfe argued that "lower Hamamelidae" were related but Juglandales (in Fagales APG) belonged in Rosidae. However, molecular data indicate that hamamelids are much more polyphyletic. Some former hamamelids that are now placed among basal eudicots (Platanus, Proteales; Tetracentron, Trochodendrales) illustrate the inferred ancestral palmate venation. Palmate venation persists into Saxifragales (now linked with Rosidae), which include taxa formerly considered lower hamamelids (Hamamelidaceae, Cercidiphyllum). Some supposedly homologous features in "higher hamamelids" appear to be convergences, such as urticoid teeth in Betulaceae and former Urticales, which molecular data nest in different clades of the Rosidae (Fagales, Rosales). As postulated by Hickey & Wolfe, pinnately compound leaves may be ancestral for the bulk of the Rosidae, with numerous reversals to simple leaves. In contrast, the ancestral leaf type in the expanded subclass Asteridae and the related Santalales, Dilleniaceae, and Caryophyllales was probably simple and pinnately veined. Molecular data indicate that the Takhtajan-Cronquist subclass Dilleniidae is highly polyphyletic. This result was anticipated by Hickey & Wolfe in their division of the group into pinnate dilleniids, most of which are linked with or assigned to Asteridae (Dilleniaceae, Ericales APG), and palmate dilleniids (Malvales, Brassicales, Cucurbitales, Malpighiales), which form several lines in the Rosidae. Reevaluation of tooth types and other leaf features in a molecular framework may reveal additional patterns of use to paleobotanists.

The Cape Blanco flora, located southeast of Cape Blanco on the southern Oregon coast, consists of leaf compression fossils from a tuff interbedded with shallow marine sandstones which constrains the paleoelevation of the bed to near sea-level. The sandstone is dated by molluscan faunal correlation to the middle Miocene Newportian Stage. This flora therefore has much potential for calibrating Miocene paleoenthalpy and paleoatmospheric carbon dioxide concentrations. Most known western North American Miocene floras are located on the Columbia Plateau or in the Californian Sierra. The far western location of the Cape Blanco flora fills a large Miocene biogeography gap and thus allows for comparisons between marine and continental climates. Leaf compressions at this locality include at least 25 morphotypes. Species level identification is possible for at least 15 of the morphotypes, and we are confident in identifying three fossil species with well known modern relatives: Quercus pollardiana, Populus eotremuloides, and Pinus ponderosoides. The nearest living relatives of the fossil species are respectively, Quercus chrysolepis (canyon live oak), Populus trichocarpa (black cottonwood), and Pinus ponderosa (ponderosa pine). All three species today are located exclusively in western North America, however only Populus trichocarpa has a modern range that overlaps with the fossil locality. The range of all three modern species currently overlaps in the coastal mountain ranges of northern California and in the northern Sierra Nevada of California. Nearest living relative comparison thus suggests a warmer climate with drier summers than currently found on the Oregon coast.

Although characters of leaf venation are often underemphasized in taxonomic and morphological studies by neobotanists, paleobotanists, especially those working on Tertiary floras, have out of necessity focused on this set of characters in their search for reliable assessments of the taxonomic affinities of fossil angiosperm leaves. Linnaeus, Bentham, Lindey and Asa Gray used botanical terms that described specific characters of leaves, such as the form, apex and base and even basic venation patterns in their descriptions. However, it was Von Ettinghausen, an Austrian paleobotanist, who was the first scientist to attempt to systematize the description of the venation patterns of leaves. In spite of this pioneering effort his methodology was not widely disseminated and very few paleobotanists accepted or used his approach. Over the years, several researchers tried to generate a formal methodology to describe the leaf characters. Turril, a Kew botanist, produced a system that consisted of the study of the relationship between the length and width of the leaf (w/l) that included a detailed treatment of the apexes and bases. From the late nineteenth to early twentieth century paleobotanists compared the gross morphology of modern leaves with that of fossils in attempts to determine the fossils' affinities. However, this practice, often considered the "picture matching" method, resulted in an incredible number of misidentifications and thus, impaired the development of the field of paleobotany by limiting its utility through resultant misleading paleoecological and evolutionary implications. It was not until the early 70s, that the leading works of Dilcher, Hickey and Wolfe, provided the solid bases and formal terminology needed for the comparative study of both leaf cuticle and leaf architecture. Precise terminology for leaf structure has proven to be a most useful tool for fossil leaf descriptions and for the reliable taxonomic placement of isolated fossil leaves. It has also proven to be of considerable value in "morphotyping" a paleoflora with the aim of reconstructing past ecosystems and paleoclimates. Based on the contributions of these latter day paleobotanists, it has been possible to carefully review previously described floras, reevaluate their species compositions, and to then interpret their paleoclimatological/paleoecological or evolutionary significance. I will discuss two floras, one from North America and one from South America, in order to illustrate how application of modern leaf architecture methodology has helped to reliably characterize paleofloras.

The sedimentary Vilui basin is situated in Western Siberia, middle section of the Lena River and lower section of the Vilui River. The basin is filled with non-marine Upper Jurassic and Cretaceous sediments. At that time a large intracontinental depression, connected with the Arctic Ocean, was at the basin. The Upper Cretaceous deposits are divided into the Timerdyakh and Linde Formations. The remains of fossil plants come only from the Timerdyakh Fm. It consists of cross-bedded sandstones and tabular siltstones and mudstones that were accumulated in channel, floodplain and lake environments.

In the Timerdyakh Fm. two stages of floral development are distinguished: the Boskhian (Cenomanian) and the Viluian (Turonian-Coniacian). The Boskhian assemblage includes about 40 species. The dominant taxa are Asplenium, Ginkgo pilifera Samyl., Sequoia minuta Sveshn., Magnoliaephyllum, Trochodendroides spp., Araliaephyllum spp., "Platanus" spp., Protophyllum, Pseudoprotophyllum, Hamamelites, Menispermites, Liriodendropsis, Cissites, Schefleraephyllum, Celastrophyllum and Cinnamomophyllum. The majority of these angiosperm genera originated in subtropical regions and migrated to the north during late Albian-Cenomanian climate warming. The Boskhian assemblage does not contain cycadophytes and other Early Cretaceous relicts that usually are common for this age.

The Turonian-Coniacian Viluian assemblage includes about 70 species. The most characteristic genera of this flora are "Platanus", Paraprotophyllum, Pseudoprotophyllum, Arthollia, Natalpa, Aralieaphyllum, Trochodendroides spp., Nyssidium, Alasia, Orulgania, Zizyphoides, Nordenskioldia, Dalembia, Hollickia, Cissites and Quereuxia. The Viluian assemblage is related with a period of cool and humid climate and dominated by platanoid and Trochodendroides-Nyssidium-Alasia plants. The genera Pseudoprotophyllum, Arthollia, Paraprotophyllum, "Platanus" and Trochodendroides underwent significant diversification in the Turonian-Coniacian. Most of the genera and species of the Viluian assemblage are characteristic for boreal warm-temperate floras and never penetrated into subtropical regions.

Floras of the Vilui basin were included in the Leno-Vilui province of the Siberian-Canadian paleofloristic realm during the Late Cretaceous and were related mostly with the Late Cretaceous floras of North-East than with neighbouring, floras of Eastern Siberia.

Exploratory analysis of data on leaf morphology and architecture is often hampered by the difficulties of handling a relatively large number of correlated variables. Any botanist knows that a large, thick, ovate, coriaceous leaf with highly organized veination, a drip-tip, and waxy cuticle was probably collected from a wet tropical rain forest with a long, hot growing season, few or no deciduous species, high species diversity, and a deep, complex photosynthetic canopy. It remains, however, difficult to describe exactly how each leaf architectural measurement relates to each ecological variable. Leaves get smaller on average as you go to higher latitudes, but also as you go to higher elevations at the same latitude or to dryer conditions at the same latitude and elevation. Dryer conditions themselves are not randomly scattered across the planet, but occur predominantly in certain latitudinal bands, continental interiors, and on the lee sides of major mountain ranges. In other words, both the explanatory and response variables depend upon each other, often non-linearly. Graphical methods provide a way to examine data without assuming independence, normality, linearity, or any of the other mathematically convenient properties that are seldom found in real data. Here I give examples of two graphical methods that have been developed in the past few decades for examining complex data with a moderate number of variables (between about 5 and 50). Most of the published procedures for describing leaves have about this number of variables, including the most prominent methodology, CLAMP (the Climate Leaf Analysis Multivariate Program), which uses 31 variables to describe the architecture of woody dicot leaves. I demonstrate implementations of these two graphical methods, the pairs plot and the corrgram, in the R statistical computing language, and show how they can be combined into a generalized pairs plot that illustrates important features of the available published CLAMP data.

Paleobotanists come in many different categories, from those with a clear focus on systematics, to those interested primarily in reconstructing environments of the past, and everything in between. Looking back from the perspective of the early 21^st century at their impact on paleobotany, it is clear that over the last 40+ years that David Dilcher and Jack Wolfe have had a significant influence on the development of ideas about fossil plant taxonomy and systematics, climates of the past (especially the Eocene), and the methodologies used in these analyses. Importantly, their influence has not been restricted to North America, although I will focus in this talk on that continent, and on climates of the Eocene. In the past 15 years, climate during the Eocene has become a preoccupation for some paleobotanists, geoscientists and climatologists interested in ‘hothouse earth’ times, and in particular how the past may provide insight into future climate change driven by changed concentrations of atmospheric greenhouse gases. It could be argued that the foundations for this interest in the Eocene were laid down by David Dilcher and Jack Wolfe. In this talk I will review the seminal works authored by these paleobotanists, and also lesser known works, that pointed the way, conceptually and methodologically, to the importance of understanding the Eocene. Leaf architecture, Leaf Margin Analysis (and more broad perspectives on leaf physiognomy and climate, such as CLAMP), the debate over nearest living relative analogy, taphonomy, paleoelevation – these were all topics explored by Dilcher and Wolfe, their contemporaries and their students and postdocs in their labs. Their seminal – and controversial – papers published in the 1960s-1970s using leaf physiognomy to reconstruct trends in climate, primarily mean annual temperature or ‘MAT’, over the Tertiary are still cited and appear in undergraduate textbooks. Past students and postdocs of Dilcher and Wolfe picked up these topics; Dolph, Manchester, Spicer, Upchurch and Wing, to name just a few, and even a generation that worked with their former students and postdocs, such as Burnham, Gregory-Wodzicki, Greenwood, Kennedy, Wiemann, Wilf, and others. A fundamental shift that was facilitated by ever smaller, faster and more sophisticated computers and easy-to-use software was the publishing of numerical estimates of MAT and cold month mean temperatures and precipitation, and controversially, even estimates of paleoelevation using ‘paleoenthalpy’. This shift was driven in part by the development by Wolfe of CLAMP (in collaborations with others, including Dilcher), but also by the challenge of reconciling new computer models of Cretaceous and Eocene climates that were at odds with what paleontologists understood were times of frost-free climates across North America. Perhaps out of pragmatism, LMA was ‘resurrected’ by Wing, Greenwood and Wilf, and the climate modeling community sought more sophisticated ways to redress the apparent discrepancies between the paleobotanically derived ‘frost-free’ continental interiors and their models. The relationship between leaf margin proportion and MAT has been shown to be essentially global (cf. New Zealand), although subject to regional variation. Recent papers have also sought to better quantify the taphonomic biases inherent in LMA and CLAMP, while others have sought to ever more precisely measure leaf-climate correlations; topics first raised in 2 papers written by Jack Wolfe and David Dilcher, 40+ years ago.

RECOGNIZING THE ALBIAN–CENOMANIAN (OAE1D) SEQUENCE BOUNDARY USING PLANT CARBON ISOTOPES: DAKOTA FORMATION, WESTERN INTERIOR BASIN, USA
Darren R. Gröcke¹, Gregory A. Ludvigson², Brian L. Witzke³, R. Matt Joeckel⁴, David F. Ufnar⁵, Martin C. Knyf¹ and Robert L. Ravn⁶

¹SIBL, McMaster University
Hamilton, Ontario, L8S 4K1, Canada

²Kansas Geological Survey
University of Kansas
Lawrence, Kansas, 66047-3726, USA

³Iowa Department of Natural Resources
Geological Survey
Iowa City, Iowa 52242-1319, USA

⁴Conservation & Survey Division
School of Natural Resources
University of Nebraska-Lincoln
Lincoln, Nebraska 68588-0517, USA

⁵Department of Geography & Geology
University of Southern Mississippi
Hattiesburg, Mississippi 39406, USA

⁶Aeon Biostratigraphic Services
6501 Shale Circle
Anchorage, Alaska 99516, USA

Analysis of bulk sedimentary organic matter and charcoal from an Albian–Cenomanian fluvial-estuarine succession (Dakota Formation) at Rose Creek Pit (RCP), Nebraska, reveals a negative excursion of ~3‰ in late Albian strata (oceanic anoxic event 1d – OAE1d). Overlying Cenomanian strata have δ¹³C values of –24‰ to –23‰ that are similar to pre-excursion values. The absence of an intervening positive excursion (as exists in marine records of the Albian/Cenomanian boundary and OAE1d) likely results from a depositional hiatus. The corresponding positive δ¹³C event and proposed depositional hiatus are concordant with a regionally identified stratigraphic sequence boundary in the Dakota Formation (D₂), as well as a major regressive phase throughout the globe at the Albian/Cenomanian boundary. Data from RCP confirm suggestions that some positive carbon-isotope excursions in the geologic record are coincident with regressive sea-level phases, and that OAEs do not always occur during transgressive phases. We estimate using isotopic correlation that the D₂ sequence boundary at RCP was on the order of 0.5 Myrs in duration. Several other sections including outcrop and cores have also been analyzed indicating that a similar duration is evident for the region. Therefore, interpretations of isotopic events and associated environmental phenomena, such as oceanic anoxic events, in the shallow-marine and terrestrial record may be influenced by stratigraphic incompleteness. Further investigation of terrestrial δ¹³C records may be useful in recognizing and constraining sea level changes in the geologic record.

A remarkable assemblage of plant and animal fossils has recently been discovered in Nakhon Ratchasima province in Northeast Thailand. The fossils were deposited in a fluvial system thought to be Middle Pleistocene in age. Plant remains include fruits, leaves, wood, rhizomes, amber, and pollen. The most common fruit type is preserved either as an elliptic endocarp with three valve-like structures arranged around the equator, or as a whole fruit with mesocarp and exocarp present and with a circular ridge surrounding the peduncle. This type shows affinity to Ziziphus (Rhamnaceae). A second fruit type consists of a globose fruit surrounded by five rather narrow wings and is similar to Dipterocarpus (Dipterocarpaceae), especially D. alatus and D. costatus. A third fruit type is an elliptic endocarp with five elongate ridges and a central cavity apical to the locules. The endocarp dehisces at least partly into five valves. The fruit type is consistent with Melia (Meliaceae). A fourth fruit type consists of a fragment of a lenticular endocarp showing affinity to Dracontomelon dao (Anacardiaceae). Rhizomes have also been recovered that are similar to rhizomes of Cyperaceae. Clear amber, as well as very well preserved leaves and wood, has also been found. The above specimens suggest the presence of a deciduous or a mixed evergreen-deciduous forest. In addition to plant fossils, a number of vertebrate fossils have also been recovered from the site, including bones or teeth of a fish, soft-shelled and other turtles, gavials, bovids, deer, Stegodon, and a hyena.

The Palaeogene Tard Clay Formation comprises a rich and well-preserved fossil flora, both leaves with preserved cuticle and fruits. In Hungary layers of the formation were recorded in the Buda and Bükk Tectonic units, both providing a rich fossil flora.

The fossiliferous sediments were deposited during the Kiscellian and based on nannoplanktons belong to the zone NP23. Both tectonic units formed a part of a Palaeogene basin that included Slovenian Palaeogene sediments. In addition to the tectonics of the area, palaeomagnetic measurements and results of other geological studies the similar character of the fossil flora corroborates the close palaeogeographic position of these units during the Early Oligocene. Some taxa were recorded exclusively from these areas, e.g. Tetrapterys harpyiarum, Ailanthus tardensis. The floras of the Bükk and Buda units share most taxa and show a high similarity with the flora of the Slovenian Early Oligocene.

In addition to the great number of ferns (Acrostichum, Blechnum, Osmunda, Pteris) and gymnosperms (Tetraclinis salicornioides, T. brachiodon, Calocedrus suleticensis, Doliostrobus taxiformis var. hungaricus, Chamaecyparites hardtii, Taxodiaceae) angiosperms are dominant: Laurophyllum div. sp., Daphnogene sp., Eotrigonobalanus furcinervis, E. andreanszkyi, Quercus lonchitis, Zizyphus zizyphoides, Engelhardia orsbergensis, E. macroptera, Sloanea elliptica, S. eocenica, Hooleya hermis, Ailanthus tardensis, Raskya vetusta, Tetrapteriys harpyiarum, Cedrelospermum flichei, C. aquense, Platanus neptuni, Matudaea menzeli, Hydrangaea microcalyx, Dioscoreites giganteus, Dioscoreaecarpum marginatum etc.

Exclusively palaeotropical elements appear in this flora, whereas temperate taxa distributed in the coeval northern European fossil floras were not recorded among plant remains of the Tard Clay. Even some taxa are definitely tropical, e.g. Sloanea (Elaeocarpaceae), Tetrapteriys (Malpighiaceae). This is well in agreement with the palaeogeographic reconstruction of the area assuming that the Palaeogene basin was part of the Alcapa terrane. Thus, the Hungarian and the Slovenian Palaeogene basins are presumed to have a more southerly geographic position during the Oligocene than that of the stable Europe at that time or their present-day position. Presumably, these areas belonged to a southern zone during the Palaeogene that was characterized by thermophilous taxa and often cited as „Palaeogene sclerophyllous belt".

The Leguminosae has a diverse and abundant fossil record, which has been well documented from numerous Tertiary age localities, primarily in North America, Europe, and Asia. The record from these areas shows a sudden appearance of diversity in the middle Eocene. The available fossil data have been useful in providing minimum ages of clades within the family and in providing historical context for modern biogeographic patterns. However, several holes exist in the known record, one of the most significant being a lack of fossils from low paleolatitudes. In this paper I will present new data that are relevant to several aspects of the fossil record of the family. Two areas in particular will be addressed, the early (pre-Eocene) record of the family, and Eocene fossils from tropical Africa. In addition, the fossil record of basal Papilionoideae, which is especially rich, will be addressed in the context of recent phylogenetic hypotheses based on molecular sequence data. Recent work with B. Jacobs (Southern Methodist University) on a middle Eocene age site (Mahenge) in central Tanzania has revealed an assemblage that is dominated by caesalpinioid and mimosoid legume leaves and fruits. The recent discovery of Paleocene age fossil fruits and leaves of an extinct member of the Papilionoideae from Wyoming is significant because these fossils represent the first evidence of the papilionoid subfamily in the fossil record. The fossils are most comparable to Bowdichia, Diplotropis, and Sakoanala in leaf and fruit structure. The membranous winged fruits characteristic of this fossil taxon are found in these and several other closely related extant genera. Similar fossil fruits, representative of additional genera of the tribe Sophoreae, are known from several other fossil localities in North America. These and other fossil representatives of the legume family can be integrated into detailed phylogenetic hypotheses to provide a clearer understanding of the pattern and timing of diversification in this important family. This is the primary goal of my continuing efforts in studying the fossil history of legumes.

Abundant plant fossils were collected in the silty mudstone, coal, and sandstone in the upper part of the Prince Creek Formation at Sagwon Bluffs, North Alaska. Poorly consolidated basal conglomerates of Sagwon Member of Sagavanirktok Formation overlies here the plant-bearing beds. Two fossil floras can be recognised in the Sagwon Bluffs Locality. Sagwon 1 Flora was first collected by Jack Wolfe in 1951 and later studied by Spicer in 1987, by Ahlberg, Herman and Spicer in 2001 and by the authors in 2005. Plant fossils were found in the lower part of the Sagwon section below coal seam 3. The Sagwon 1 Flora comprises about 30 species, with Metasequoia occidentalis, Quereuxia angulata and Corylites beringianus being the most abundant. Other characteristic plants are Equisetum arcticum, Onoclea hesperia, Mesocyparis, Fokieniopsis aff. catenulata, Haemanthophyllum, Sparganiophyllum, Phragmites, Trochodendroides, Cissites, Nyssidium, "Cocculus", Rarytkinia, Ettingshausenia, Celastrinites, Castaliites, Liriophyllum cf. aeternum, a rosid leaf (cf. Rubus), several fructifications etc. The Sagwon 1 Flora shows the closest similarity to the late Maastrichtian Koryak Flora of the Amaam Lagoon in North-eastern Russia. Corylites beringianus, Trochodendroides and Metasequoia occidentalis are dominants of both floras; other taxa in common are Equisetum arcticum, Onoclea hesperia, Metasequoia cones, Nyssidium arcticum, Liriophyllum cf. aeternum, as well as representatives of the genera Mesocyparis, Haemanthophyllum, Sparganiophyllum, Rarytkinia, Ettingshausenia, Celastrinites and Cissites. Sagwon 2 Flora was first discovered by the authors in summer 2005. It comes from poorly exposed sandstones between coal seams 3 and 4 in the northern part of the Sagwon section. It differs from the Sagwon 1 Flora in both systematic composition and dominating species. Sagwon 2 Flora comprises Metasequoia occidentalis (many), Metasequoia mail cones, Taxodium (?) sp. (many), Mesocyparis (?) sp., Tiliaephyllum tsagajanicum (predominates), Trochodendroides ex gr. arctica, "Acer" arcticum, Viburniphyllum sp., fructification, bract of unknown affinity. Although much less diverse, the Sagwon 2 Flora is similar to the Danian Upper Tsagaian Flora of the Amur River Region, south of the Russian Far East. The latter flora is characterised by abundant Tiliaephyllum tsagajanicum, with Metasequoia occidentalis, Taxodium, Mesocyparis, Trochodendroides ex gr. arctica, Viburniphyllum and "Acer" arcticum being also numerous. Palynological assemblage from the lowermost part of the Sagwon section indicates the Paleocene (but not the earliest Paleocene) age (G.N. Alexandrova, pers. comm., 2006) whereas dinoflagellate cysts Paleoperidinium pyrophorum found in the upper part of the section (between coal seams 5 and 6) indicate that the age of the plant-bearing beds is not younger than Selandian. Therefore, the Sagwon 1 Flora is most likely of Danian age, and Sagwon 2 Flora - possibly of Danian (?) - Selandian age. The close similarity between the late Maastrichtian Koryak Flora and the Danian Sagwon 1 Flora implies that the floristic change near the Cretaceous-Tertiary boundary in the North Pacific Region was not affected by any catastrophic event and may, in all likelihood, be due to a long-term climatic and evolutionary change and plant migration. The Koryak Flora possibly sourced many of the Sagwon 1 taxa as the Palaeocene warming took place. This progressing warming, which had its maximum in the early Eocene, probably allowed the plants typical of the Danian Upper Tsagaian Flora to invade the North Alaska during the Danian (?) - Selandian time and to compose the Sagwon 2 Flora.

Three decades ago Jack Wolfe published seminal papers documenting the relationship between leaf morphology and climate, and used the forests of eastern Asia as an analogue to reconstruct climate and vegetation at Cenozoic sites in the Pacific Northwest. More recently he quantified that relationship using a much larger and climatically broader data set, aiming ultimately to apply the methodology globally to angiosperm leaf fossils. This step forward stimulated a host of studies aimed at defining leaf-climate relationships for various geographic regions using the same and other methods. Finding a method appropriate for the reconstruction of climate from tropical African leaf fossils was sought in order to improve the record from poorly known areas and time intervals. As shown by both Wolfe and Dilcher, rainfall is positively correlated with leaf size, a relationship that is robust and significant in the tropics. However, plants respond in complex ways to a combination of both rainfall and temperature. Therefore, in this paper we explore the relationships among leaf morphological characters and evapotranspiration, a measure of the combined effects of temperature and rainfall upon water availability. A better understanding of these relationships will improve our interpretation of fossil leaves with respect to the combined influences of climatic parameters in the past. Late Oligocene leaf assemblages from Chilga, northwestern Ethiopia, is a case study in which we explore the ramifications of evapotranspiration for plant-water relations, and report both mean annual and seasonal rainfall amounts based upon leaf size data; and mean annual temperature based upon oxygen isotope the analysis of paleosol phyllosilicates.

Many mechanisms have been proposed to explain the high plant diversity in the Neotropics today, but little is known about diversification patterns of Neotropical floras through geological time. We compiled the longest time series for plant diversity of the Neotropics using the pollen and spore record from eastern Colombia and western Venezuela. The time series spans from the Maastrichtian to the middle Miocene. The record shows a low diversity Paleocene flora, a significantly more diverse early to middle Eocene flora exceeding Quaternary levels, with a decline at the end of the Eocene and early Oligocene. The fluctuations in diversity correlate with global mean annual temperature. However, climate change is unlikely by itself to drive the observed diversity pattern, because tropical terrestrial temperature does not seem to change over time. Rather, the correspondence results from the control climate exerts on the area available for tropical plants to grow. Larger tropical areas during global warming support more species locally in the tropical latitudes, while global cooling reduces tropical areas, driving extinction in the tropics. Modern high neotropical diversity seems a recent phenomena, possibly linked to the rising of the Andes mountains 4-6 Million years ago.

Kirk R. Johnson¹, Peter Wilf², N. Rubén Cúneo³, Maria A. Gandolfo⁴, Ari Iglesias⁵, Cynthia C. González³, Conrad C. Labandeira⁶

⁵División Paleobotánica Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n° 1900, La Plata, Argentina

The utility of Cretaceous and Paleogene megafloras for assessing floral diversity and paleoclimate has been greatly enhanced by employing large sample sizes from quantitatively collected bench quarries in a geochronologically-constrained stratigraphic framework. Beginning in 1997, we have been recollecting known floras and discovering new ones from Paleogene strata of Chubut and Río Negro Provinces with the intent of building an understanding of southern mid-latitude terrestrial paleoclimate and biodiversity. In order of decreasing age, the floras collected to date include the early Paleocene (Danian, ~62 Ma) Palacio de los Loros flora and associated sites from the Salamanca Formation near Sarmiento; the early Eocene (~52 Ma) Laguna del Hunco flora from a volcanic lake sequence in the Río Chubut valley of Central Chubut; and early Eocene Pampa de Jones and middle Eocene (~47.5 Ma) Río Pichileufú floras from the Chubut-Neuquén borderlands near San Carlos de Bariloche. Our approach has been to prospect for and extensively quarry sites that preserve abundant megafossils. Each of the quarries is collected in a manner that accounts for all fossils and thus represents an unbiased sample of the buried flora. The Salamanca floras occur in clay plug deposits of a abandoned channels and in channel sands while all of the younger sites occur in tuffaceous lacustrine sediments. We have collected more than 1000 identifiable specimens from each locality except Pampa de Jones. All floras are dominated by angiosperms but all also contain a distinctive conifer element. Both the angiosperms and the conifers show a strong Gondwanic affinity, particularly to extant humid tropical and warm temperate floras of Australasia. Examples include Araucaria section Eutacta, Acmopyle, Dacrycarpus, and cf. Papuacedrus in the conifer group, and Akania, Gymnostoma, diverse Cunoniaceae, and possible Eucalyptus in the angiosperms. Rarefaction analyses of the floras shows that the Eocene floras are significantly more diverse than the Paleocene ones, a pattern that mimics what is known from identically collected, comparable, well-sampled floras in North America, and that both Paleocene and Eocene Patagonian floras are much more diverse than their North American counterparts. We recognize almost 200 plant organ morphotypes from the Laguna del Hunco flora alone. Moreover, the Patagonian floras bear extraordinarily diverse insect damage, and at Laguna del Hunco the diversity of insect damage is the highest we have observed for the Cenozoic. These results show an ancient history of high diversity in thermophilic South American floras and their associations with insects, and they raise the interesting possibility that the end-Cretaceous event was less severe in Patagonia, far from Chicxulub, than in the Western Interior U.S. Collectively these floras begin to define the floral composition and taxonomic and ecological diversity of the Patagonian Paleogene and set the stage for planned exploration into the poorly sampled Late Cretaceous rocks of Patagonia.

THE PALEOCENE UPPER TSAGAYAN FLORA FROM THE AMUR RIVER REGION, RUSSIAN FAR EAST: PALEOECOLOGY AND AGE

The Late Cretaceous - Early Paleogene Tsagayan Formation comprises non-marine clastic deposits exposed throughout Zeya-Bureya Basin in Amur Province, Russian Far East. The Tsagayan plant fossils and reptilian remains were studied since the end of the 19^th century (Heer, 1878; Konstantov, 1914; Poyarkova, 1939; Kryshtofovich and Baikovskaya, 1966; Krassilov, 1976; Kamaeva, 1990; Flora and dinosaurs…, 2001; and other). Intensive collecting over the last several years has provided new data on the composition of the Tsagayan Flora (Akhmetiev et al., 2002; Maslova and Kodrul, 2003; and other).

Four distinct megafossil plant assemblages were recognized within the Lower Paleogene part of the Tsagayan Formation. The Upper Tsagayan floristic assemblage was obtained from the upper part of the Upper Tsagayan Subformation in Arkhara Hill, Arkhara-Boguchan and Raichikhinsk coal fields localities. This flora is characterized by a very low diversity in relation to other Paleocene floras of the Amur River Region. Only 22 fossil plant taxa were found in many localities of the Upper Tsagayan Flora. Four species, Zizyphoides flabella, Trochodendroides arctica, Tiliaephyllum tsagajanicum and Archeampelos acerifolia predominate in this flora and represent about 85% of all leaf impressions. Metasequoia occidentalis, Platanus raynoldsii and reproductive structures Nordenskioldia borealis, Nyssidium arcticum and Trochodendrospermum arcticum are also abundant. The other taxa comprise fern (Arctopteris), Ginkgo, evergreen and deciduous conifers (Picea, Pinus, Pseudolarix, Fokieniopsis, Glyptostrobus, Sequoia, Taxodium) and angiosperms belonging to Sapindaceae (Dipteronia) and Cornaceae (Cornus) families. Plant assemblage of the same age from the Baishantou Member of the Wuyun Formation on the right bank of the Amur River (Heilongjiang Province, China) contains additionally Onoclea, Nyssa and Juglandiphyllites.

The plant fossils represented by leaf impressions, shoots, cones, fruits, infructescences and seeds were recovered from two sedimentological facies. Coarsely laminated and thin-bedded siltstones with leaf mats are interpreted as crevasse splay and levee deposits (Krassilov, 2003; Suzuki et al., 2004). Gray claystones with dispersal plant and insect remains reflect deposition in shallow floodplain ponds. The composition of the plant assemblage depends on depositional environment, whereas ratio of dominants and accessory elements in the flora remains stable.

A lowland coniferous-broadleaved forest plant community is reconstructed for the Late Tsagayan time.

The plant-bearing deposits are dated palynologically as Early or Late Danian (Markevich et al., 2004; Flora and dinosaurs…, 2001). However, the Upper Tsagayan Flora is very similar to the depauperate Tiffanian floras of North America (Hickey, 1980; Crane et al., 1990; Hoffman and Stockey, 1999; Gemmill and Johnson, 2001). In summer 2005 a flora similar to the Upper Tsagayan Flora was collected in Northern Alaska. This Alaskan flora is dated as Selandian based on palynological data (D. Jolley, pers. com.). Therefore, judging from these correlations, we suppose that the Upper Tsagayan Flora is probably Selandian in age. The relative lower diversity of these floras possibly reflects a climate cooling.

In cooperation with sedimentologists and palynologists a model of terrestrial palaeoecosystem of the Bohemian massif was developed. It consists of four main groups of palaeoenvirnoments: mesofytic upland, flood plain (braided and meandering river), swamp and salt marsh. Mesofytic palaeonvironment is represented by vegetation showing xerophytic characters like papillae, thick cuticles, and sunken stomata. The plant remains are usually very fragmentary. The vegetation consists of ferns (e.g. Phlebopteris dunkeri), gymnosperms (e.g. Zamites bayeri, Sagenopteris variabilis), and limited amount of angiosperms (e.g. Dicotylophyllum sp.). Vegetation from flood plain of braided river is represented virtually by angiosperms Myrtophyllum angustum, M. geinitzii, Grevilleophyllum constans showing entire-margined leaves with drip-tips and associated with reproductive structures Progocladus lauroides and Mauldinia bohemica. Vegetation of meandering river shows high diversity of plants including ferns Gleicheniphyllum sp., Schizaeopsis bohemica, gymnosperms Nilssonia ssp., Microzamia gibba and angiosperms Debeya coriacea, Aralia kowalewskiana, Ettingshausenia bohemica. Plants showing xerophytic characters like papillae, thick cuticles and sunken stomata represent the salt marsh sea-influenced palaeoenvironment. The plant assemblage is of low diversity consisting mostly of gymnosperms (Frenelopsis alata, Eretmophyllum obtusum, Dammarites albens) and two angiosperms (Pseudoasterophyllites cretaceus „Diospyros" cretacea).

First megafossils of Reevesia Lindl., a member of Malvaceae, Helicteroideae known so far only by dispersed pollen in the Tertiary, are reported herein. Three associated organs have been recovered in one layer exposed in the Bílina opencast mine within the brown-coal Most Basin in North Bohemia, Early Miocene in age. Detached fruit valves of Reevesia sp. n. share all important characters with those of obovoid loculicidal capsules produced by the extant members of Reevesia (E and SE Asia) together with often included Veeresia (Mexico, Nicaragua). An associated winged seed sharing the overall morphology with those of Reevesia (and some other genera) has been assigned to the morpho-genus Saportaspermum Meyer & Manchester. Abundant associated foliage corresponds to an already well-known morpho-species "Ficus" truncata Heer sensu Bůžek (1971) and matches in gross morphology various malvalean genera, in particular Reevesia (species from SE a E China).

The associated assemblage is dominated by deciduous arboreal elements, such as Taxodium dubium of the conifers and broad-leaved Acer tricuspidatum, Acer integerrimum, Alnus julianiformis, Cercidiphyllum crenatum,"Ficus" truncata, Paliurus tiliifolius, Parrotia pristina, Salix haidingeri and Ulmus pyramidalis. The other accompanying plants include Glyptostrobus europaeus (twigs), Berberis berberidifolia ( leaves), Carpinus sp. (involucres), Chaneya oeningensis (perianth), Fraxinus macroptera (fruit), "Juglans" acuminata (leaflets), Leguminosites sp. (leaflets), Liquidambar europaea (leaves), Pungiphyllum cruciatum (foliage), Podocarpium podocarpum (foliage), Quercus rhenana (leaves), Rosa europaea (leaflets), Schenkiella credneri (fruit), Theaceae gen. (foliage) and Zelkova zelkovifolia (leaves and foliage twigs). According to the previous vegetation analyses undertaken in the Miocene plant record of the Most Basin, the assemblage belongs to a drier riparian forest formation on fertile alluvial soils (Ulmus - Parrotia association by Kvaček and Bůžek). A high proportion of deciduous elements cannot be explained intuitively as indication of more severe climatic conditions, because of the presence of sabaloid palms in adjacent layers. The climate was certainly not colder than warm-temperate, almost frostless and with high annual humidity well distributed throughout the year.

Multidisciplinary investigations were carried out in the Mataschen clay pit near Feldbach in Styria (Austria). The base of the almost 30 m thick sedimentary sequence is correlated to the early Late Miocene by regional geology and to the regional stage Pannonian "zone B" by brackish molluscs. The base of the sequence yielded invertebrates, vertebrates, and plant remains of swampy lowland environments (Gross 2004, Ćorić & Gross 2004, Harzhauser 2004, Kovar-Eder 2004, Meller & Hofmann 2004, Schultz 2004, Tempfer 2004, all in Gross ed. 2004).

From the upper part of the section, an exceptionally rich leaf flora was excavated. Thirty-eight species were determined, most of them by cuticular analysis. Among azonal taxa, only Myrica lignitum, Platanus leucophylla, and Ulmus pyramidalis are abundant, while Glyptostrobus europaeus, Alnus, Acer tricuspidatum, and Nyssa occur in single or few specimens only. Zonal species diversity is distinctly higher (27 taxa) than the diversity of azonal ones, and 60 % of the zonal taxa were probably evergreen. Among these, three new species of Gordonia, and new species of Schima, Symplocos, and of Ericaceae (gen. indet.) are recognized. Five species of Lauraceae, 4 Theaceae, 2 Hamamelidaceae (among these Distylium), one of Symplocos, and Trigonobalanopsis rhamnoides indicate close relations of this taphocoenosis to floras of the "Younger Mastixioid" type that flourished in large parts of Europe during the Early to early Middle Miocene. The peculiar mixture of evergreen and deciduous taxa furthermore indicates relations to Late Miocene/Early Pliocene floras of southern parts of Europe (Romania, Northern Mediterranean). In comparison, the similarities to the rich Late Miocene floras of Middle Europe are rather weak.

Based on the floristic composition, the evergreen broad-leaved forests (i.e. oak laurel forests) of southeast Asia at their ecotone towards the mixed mesophytic forests constitute the most closely related modern zonal vegetation type. They thrive under a warm and humid Cfa-climate with an MAT range of approximately 15 to 19 °C, an MAP range of 1280-1950 mm, and no average temperature of the coldest month below 0 °C, although occasional frosts are possible.

The Mataschen flora differs significantly from previously investigated floras of the Late Miocene in this part of Europe. This raises the question whether the flora reflects a local, climatically favourable refuge or/and a favourable climate fluctuation.

The Miocene is characterized by a series of key climatic events which led to the establishment of the modern global climate system. Associated with them are vegetation changes such as the establishment of grasslands and the rise of C4 plants. Although both, climatic trends and C4 plant evolution are thought to be influenced by the long-term CO₂ fluctuations previous pCO₂ reconstructions and modeling studies have disputed the role of CO₂ as a forcing factor. Here we present stomatal frequency data from multiple and independently calibrated tree species that reveal pronounced CO₂ fluctuations since the late Oligocene. CO₂ fluctuations in the early to middle Miocene are of such a magnitude that they may have driven much of the temperature variation and major climatic events since the late Oligocene. Warm intervals such as the late Oligocene and the mid-Miocene climatic optimum are characterized by significantly elevated CO₂ levels of about 500 ppmv whereas the major cooling events in the early Miocene and the middle Miocene are characterized by CO₂ drops down to 340ppmv and 280ppmv, respectively. The effects of the reconstructed Oligocene-Miocene CO₂ fluctuations on C3 plant photosynthesis have been tested with plant physiological models at different growth temperature simulating different climate regimes. At high growth temperatures (25-35 ºC) max. assimilation rates were drastically reduced as a result of CO₂ declines from above 500 down to 300 ppmv, or below, while max. assimilation rates are largely unaffected at low leaf growth temperatures (15-20 ºC). The photosynthesis models indicate that in warm tropical climate regimes during the early and middle Miocene photorespiration and dark respiration became a limiting factor for CO₂ assimilation in C3 plants. Thus, CO₂starvation during the Miocene may represent a significant environmental stress factor that resulted into the development of counter strategies and modifications that improved the efficiency of C3 photosynthesis and ultimately lead to the rise of C4 plants. Intriguingly, geochemical evidence reveals the first significant C4 biomass in the African vegetation during the middle Miocene low CO₂ period. The first occurrence of C4 plants as suggested by molecular phylogeny, about 20 Myrs ago, coincides approximately with the CO₂ drop in the early Miocene. Consequently, our results point to atmospheric CO₂ as a pivotal environmental factor that influenced both, climate and the evolution of C4 photosynthesis in the Miocene. Whether the origin of C4 photosynthesis dates further back into the Oligocene and coincides possibly with low CO₂ conditions awaits still further verification.

BUILDING ON JACK WOLFE’S NEOGENE FLORAS OF ALASKA

Estella B. Leopold, Linda Reinink-Smith and Gengwu Liu

University of Washington, Quaternary Research Center, Box 351800, Seattle WA 98195 USA

It was Jack A Wolfe who correctly challenged the widely held theory that our deciduous forest types originated in the Arctic (e.g. Ralph Chaney’s ‘Arctotertiary Geoflora Theory’). Wolfe laid the important paleobotanical groundwork in Alaska. He first worked with Dave Hopkins and Leopold to establish the basic stratigraphic and floral sequence in the Cook Inlet area of Alaska (Seldovian, Homerian and Clamgulchian stages) in which leaves correlating with Japanese floras and K-Ar dates established that the upper Kenai rocks were not Eocene but Miocene. Clyde Wahrhaftig took Wolfe and Leopold to the field to study the sequence of floras north of Denali; here again the floras were Miocene in age and pollen identifications supported Wolfe’s leaf floras. Tom Ager and James White in the 1990’s put together the story of Miocene floras between Denali and the upper Yukon River. Gengwu Liu and Leopold noticed that in the thermal maximum of the middle Miocene (the upper Seldovian Stage, ca 16-15 Ma), identical floras (similar to forests of Connecticut) occurred all across the Beringian region, from latitudes 60° to 70° N, and similarly between Chutkotka, Anchorage and the Porcupine River. After Seldovian time the climate appeared to deteriorate, and the forests younger than 12 Ma lost their warmth-loving genera one by one, and became impoverished. A strange mix of conifers and Pterocarya, Quercus, Ulmus, persisted to the end of the Tertiary. More detail was needed at the type Homerian.

	Paleobotanical Stage	Coastal, Cook Inlet; Wolfe et al. 1966; Reinink-Smith and Leopold, 2005	North of Denali, Nenana; Leopold and Liu, 1994; Wahrhaftig et al. 1969	Dates
Pliocene-Upper Miocene-	Clamgulchian	Mixed Conifer	Mixed Conifer