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.
University, Evanston, Illinois, 60208, 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.
Jonathan I. Bloch
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.
David Christophel, Peter Gordon and Tuyen Nguyen
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.
Margaret E. Collinson
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.
Museum of Natural History
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.
A cladistic analysis suggests that U. okanaganensis is nested within the subgenus Ulmus that is a paraphyletic grade basal to the subgenus Oreoptelea. Ulmus chuchuanus foliage shows affinities to the subgenus Ulmus, while the associated fruits display affinities to the subgenus Oreoptelea.
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
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.
VALUE AND EVOLUTION OF LEAF ARCHITECTURE ACROSS THE ANGIOSPERMS IN LIGHT
OF MOLECULAR PHYLOGENETIC ANALYSES
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 21st 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.
THE ALBIAN–CENOMANIAN (OAE1D) SEQUENCE BOUNDARY USING PLANT CARBON
ISOTOPES: DAKOTA FORMATION, WESTERN INTERIOR BASIN, USA
of Natural Resources
& Survey Division
Geography & Geology
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".
More than 60% of the taxa recorded in the Tard Clay do not pass the Kiscellian/Egerian boundary and are not documented from Late Oligocene floras of the Central Paratethys, e.g. Doliostrobus taxiformis var. hungaricus, Chamaecyparites hardtii, Quercus lonchitis, Zizyphus zizyphoides, Sloanea elliptica, S. eocenica, Hooleya hermis, Ailanthus tardensis, Raskya vetusta, Tetrapteryis harpyiarum, Matudaea menzeli, Hydrangaea microcalyx, Dioscoreites giganteus, Dioscoreaecarpum marginatum, etc.
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.
Alexei B. Herman1, Maria G. Moiseeva1, Robert A. Spicer2, Anders Ahlberg3, David W. Jolley4
2The Open University
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
1Denver Museum of Nature & Science, Denver, Colorado, 80212, USA
2Pennsylvania State University, University Park, Pennsylvania USA
3Museo Paleontológico Egidio Feruglio, Trelew, Chubut, Argentina
4Cornell University, Ithaca, New York, USA
5División Paleobotánica Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque s/n° 1900, La Plata, Argentina
6Smithsonian Institution, Washington, DC
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.
Tatiana M. Kodrul and Mikhail A. Akhmetiev
Geological Institute, Russian Academy of Sciences, 119017 Moscow, Russia
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 19th 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).
FRUITS OF REEVESIA (MALVACEAE, HELICTEROIDEAE) AND ASSOCIATED PLANT
ORGANS (SEED, FOLIAGE) FROM THE LOWER MIOCENE OF NORTH BOHEMIA (CZECH
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.
Johanna Kovar- Eder1 and Lilla Hably2
Museum für Naturkunde Stuttgart
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.
Wolfram M. Kuerschner1 and Z. Kvacek2
1Faculty of Sciences
2Faculty of Sciences
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, CO2 starvation 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.
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.
Linda Reinink-Smith, a student of Dave Hopkins, began post-doctoral studies in Leopold’s lab to establish the true character of the type Homerian (Late Miocene) flora at Homer, Alaska. Her results were puzzling as now we saw that the type Homerian along the coast was similar to the upper Seldovian, while the interior Homerian was much deteriorated and cooler (or drier) in nature. We asked ourselves why this might be, and one answer is that the Alaska Range, which was probably uplifted during the late Homerian (~ 6 Ma ) may have cast a "rain shadow" that caused a loss of summer precipitation and a development of more extreme climates north of the range. Our paper on this in Palynology also reports the occurrence of Podocarpaceae pollen with a wide range of taxonomic types as enigmatic minor elements typical of the Late Miocene. Further dating is needed to clarify these relationships.
Wolfe et al., 1966, USGS Prof. Paper.398a; Leopold and Liu 1994, Quaternary Internat. v.22-23; Wahrhaftig et al 1969, USGS Bull. 1274D; Reinink-Smith and Leopold, 2005, Palynology, v.29.
Fossil horses (Family Equidae) have adapted to a variety of plant foods during their 55-million-year history. Evidence for the diets of fossil horses comes from inferences derived from tooth morphology, associated plant fossils, and stable carbon isotope ratios of tooth enamel.
The traditional interpretation of the evolution of diet in mammalian herbivores, such as horses, comes from discernable changes in tooth morphology. Based on modern analogs, herbivores with short-crowned teeth have been primarily browsers, whereas those with high-crowned teeth are interpreted to have been grazers. While this model remains solid, there are numerous exceptions. Recent studies have shown that "you are what you eat," and fossil herbivores incorporate into their teeth the carbon isotope ratios of their plant foods. Because teeth have a compact mineral lattice and are highly durable, the original carbon isotope dietary ratios are characteristically preserved in the fossil record. This new line of evidence provided from stable isotope analysis requires significant reinterpretation of mammalian herbivore feeding ecology, particularly for later stages of horse evolution.
Horses from the Eocene through early Miocene (55 to ~20 million years ago) have exclusively short-crowned teeth and therefore are interpreted to have been browsers. The earliest horses, including "eohippus" (also previously referred to as Hyracotherium) from Colorado were interpreted to have lived in open park-like woodlands and savannas and may have fed on low ground cover, including herbaceous dicots and ferns, but not grass. In a rare discovery, Eocene horse-like palaeotheres (Palaeotheriidae) from Messel, Germany have fossilized gut contents indicating a diet of grapes. All early Tertiary horses analyzed so far from this time interval yield relatively negative carbon tooth isotope signatures (d13C <-10 per mil) indicating a diet consisting exclusively of C3 plants (mean d13C ~ -25 per mil). There is no evidence for C4 grasses during this time recorded from fossil horse (or any other mammalian herbivore) teeth.
During the middle Miocene, after ~20 million years ago, fossil horses demonstrate a rapid increase in the evolution of high-crowned teeth. This has traditionally been explained as a coevolutionary response to the spread of new food resources in the northern hemisphere, i.e., grassland biomes. Evidence from carbon isotopes, however, does not show a corresponding shift in d13C values until the late Miocene, ~7 million years ago. This lack of isotopic shift indicates that middle Miocene high-crowned horses probably fed on C3 grasses, not the C4 grasses that are widespread in temperate and tropical regions today. During the late Miocene through Pleistocene, carbon isotopic evidence indicates that rather than being specialized grazers, horses diversified their diets to include grasses and other plants depending upon competition with other sympatric herbivores and available plant foods. Thus the evolution of high-crowned teeth confers the evolutionary advantage of being able to exploit a variety of plant foods.
The abundant 55-million-year record of fossil horses is a classic example of macroevolution and illustrates an herbivore’s adaptation to changing plant foods in the global terrestrial landscape. As additional fossil evidence is discovered and new analytical techniques are developed, our understanding of the Equidae will advance and be further refined.
Rolf W. Mathewes1 and Peter Mustard2
Sedimentary rocks within the Fraser Lowland near Vancouver, B.C. range from late Cretaceous to Tertiary in age. The Tertiary (Chuckanut) basin comprises the Chuckanut Formation in Washington State, and the stratigraphically equivalent Huntingdon Formation in the adjacent Fraser Lowland. The Chuckanut has been variously interpreted as latest Cretaceous to Eocene based on biostratigraphy, but fission track ages on zircons suggest a predominantly Eocene age (~55 Ma and younger), although the most basal rocks have not been dated radiometrically. Several palynological studies, however, suggest that Paleocene rocks are present in the basal Chuckanut.
The Kanaka Creek exposures of arkosic sandstones and mudstone on the northern flank of the basin in B.C. have been interpreted as the basal part of the Huntingdon Formation, but no radiometric dates are available.
Plant megafossils consist of carbonaceous compressions and impressions of ferns, conifers, and angiosperm leaves. Two species of Woodwardia ferns are present, and Glyptostrobus and Sequoia- type foliage dominates the conifer assemblage. Many primitive or extinct angiosperms have been recorded, including Platanus, several Macclintockia morphotypes, Macginitiea, Macginicarpa, Corylopsiphyllum-type and others. Particularly significant are identifications of Platanus bella, Viburnum antiquum, Celtis aspera, and two ovulate cones of cf. Fokienia ravenscragensis. The last four taxa are only known elsewhere only from Paleocene rocks. Floristic similarities are apparent with other Paleocene localities in western North America, and also with the Paleocene flora of Greenland as described by Koch (1963), suggesting a terrestrial migration corridor between Greenland and North America.
Preliminary palynological investigations record fungi, fern spores, gymnosperm and angiosperm pollen. The palynoflora records a mixed assemblage of Late Paleocene to Eocene palynomorphs. The presence of rare Ilex, Ulmus/Zelkova, Liquidambar, and the spore Trilites solidus suggest an Eocene age, comparable to the younger Kitsilano member of the Huntingdon Formation near Vancouver. A late Paleocene age is indicated by the presence of Paraalnipollenites, Intratriporopollenites, Insulapollenites, and possibly some other types.
The presence of index fossils of both ages at this locality suggests the hypothesis that the Kanaka exposures may straddle the Paleocene-Eocene boundary, an idea that will be tested by more detailed sampling and analysis.
Jennifer C. McElwain1, Mihai E. Popa2, Stephen P. Hesselbo3, Matthew Haworth3 and Finn Surlyk2
The contribution of vegetation change to the rise of Dinosaurs in the late Triassic and early Jurassic has received little attention. Yet, modern ecological theory predicts that a disruption or loss of primary productivity can result in a cascade of extinctions throughout the entire ecosystem from primary consumers to the highest trophic levels. Here we show that terrestrial vegetation underwent major ecological upheaval before and coincident with the Triassic-Jurassic mass extinction boundary in the region of Astartekløft in East Greenland. From a paleoecological database of 4303 fossil plant specimens we document (1) complete turnover of ecological dominance within the plant canopy, (2) loss of the mid canopy niche, and (3) loss in generic level richness and evenness. Our paleoecological analyses reveals that extinctions were highest amongst taxa of moderate abundance and with specialized reproductive strategies, that likely relied on insect vectors for pollination. Selective extinctions are also observed in understory and floodplain taxa with large leaves. Ecosystem recovery at the generic level was relatively rapid, particularly among peat forming plant communities, however plant communities in the post extinction interval were highly unstable, showing much higher species level turnover than observed in pre-boundary time. Despite relatively minor worldwide extinction among higher taxonomic groups at the Triassic-Jurassic extinction boundary, these marked paleoecological changes and species level extinctions were of sufficient magnitude to severely disrupt primary production and likely resulted in emigration and/or extinction of primary consumers contributing significantly to vertebrate turnover at the Triassic-Jurassic mass extinction boundary.
Paula J. Mejia¹; David Dilcher¹ and Carlos Jaramillo²
¹Florida Museum of Natural History, Gainesville, Florida, 32611, USA
²Smithsonian Tropical Research Institute, Panama City, Panama
One of the major unanswered questions in plant evolution is when and how angiosperm diversification took place. It is widely believed that angiosperms originated in the tropics and then radiated to higher latitudes to become the dominant component of terrestrial plant ecosystems worldwide by the end of the Cretaceous. However, the majority of previous work on tropical palynofloras has used mostly qualitative data. In this study we use quantitative palynological data from the Lower and Upper Cretaceous sediments of the Upper Magdalena Valley in southwestern Colombia to assess the diversity and abundance of early tropical angiosperms. Contrary to accepted wisdom, we found that angiosperm pollen was neither the most diverse nor the dominant element in the tropical ecosystems studied. This was found to be the case in both the Lower and the Upper Cretaceous. In fact, when compared to sediments of similar age from North America and Europe, it appears that the higher latitudes rather than the tropics maintained a higher diversity and greater relative abundance of angiosperm pollen during the Lower Cretaceous. Although preliminary, this study suggests that perhaps angiosperms diversified and radiated from high to low latitudes, and highlight the importance of expanding our understanding of tropical ecosystems during this time of angiosperm evolution and geographical radiation.
Geological Survey, Neulinggasse 38, A-1030 Vienna, Austria
The discovery of Aristolochia leaves in Late Miocene sediments in Austria have led to an investigation about the Miocene and Oligocene fossil records in Central Europe, which is still in progress.
The modern Aristolochiaceae are represented by seven genera and 400-600 species, which are mainly growing as shrubs, lianas, and herbs in tropical and subtropical, rarely in temperate areas. The genus Aristolochia includes about 300-500 species, which are distributed in tropical to temperate areas. A centre of diversity is Southern and Middle America. One herbaceous species, Aristolochia clematitis L., today also occurs in Austria, growing in riparian forests.
Aristolochia leaf and fruit remains have only been sometimes reported from Neogene leaf assemblages from Central Europe. The fruit remains, which have been described by Heer (1856, 1859), Engelhardt (1908) and Kafka (1911) have been already rejected by Kirchheimer (1957). Since that time Aristolochia fruits and seeds have not been recorded from Central Europe. Some species of Aristolochia, based on few leaf remains, have been described by Weber (1852), Wessel & Weber (1856), Heer (1856, 1859), Ettingshausen (1888), and Principi (1916). However, according to an extensive morphological comparative study including more than 80 modern species of Aristolochia in the herbaria of the Natural History Museum in Vienna and of the Botanical Institute of the University of Vienna (also with the other genera of the family and some genera of other families with a similar leaf morphology, e.g. Convolvulaceae) these fossil records cannot be accepted as Aristolochia records. The leave imprints are more similar to Asarum (Aristolochiaceae), Calystegia (Convolvulaceae), Smilax (Smilacaceae).
The new two leaf imprints show all the morphological features, which have been recognized as typical for Aristolochia leaves. Moreover, the differences between the two specimens fit very well with the variability of leaves of one shoot. The associated leaf and diaspore assemblages of the locality are dominated by aquatic and riparian elements.
Herbert W. Meyer1, Deborah Woodcock2, William McIntosh3 and Nelia Dunbar3
1National Park Service, Florissant Fossil Beds National Monument, PO Box 185, Florissant, CO 80816, USA
2Marsh Institute of Clark University, 950 Main Street, Worcester, MA 01610, USA
3New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801, USA
El Bosque Paleontologico Piedra Chamana is an Eocene petrified forest located in the northern Peruvian Andes (northern Cajamarca; 79°10’E,6°35’S). The site is designated as protected under the Cultural Patrimony of the Nation by the government of Peru. Our work, supported by a grant from the National Science Foundation, involves a dynamic combination of scientific research, conservation, development of an inventory and monitoring database, and design of an interpretive plan.
The petrified forest occurs in volcanic and volcaniclastic rocks of the Huambos Formation and contains a diverse assemblage of well preserved permineralized woods and leaf impressions. Preliminary 40Ar/39Ar dating of associated rocks yields a date of 39 Ma (Middle Eocene), but dating of new samples having closer stratigraphic context to the fossils is underway. The fossiliferous sequence includes a paleosol overlain by ashfall and lahar deposits containing large (1-2 cm) accretionary lapilli. Woods and leaves associated with the paleosol and ashfall deposits, including trees buried in situ, provide a highly localized representation of the paleovegetation. Preliminary field examination of a small sample of fossil leaves shows that they are predominantly entire-margined and microphyllous in size, with some notophylls and rare mesophylls, suggesting a megathermal climate lacking high precipitation. Fossil wood is also present in high abundance and diversity in the overlying lahar; various lines of evidence, such as the diversity of monocots (palms and other monocots) and the low incidence of growth rings among the dicot woods, indicate that this assemblage represents tropical lowland forest. Current elevation at the site is 2500 meters, suggesting significant post-depositional uplift.
Our work also has involved completing a paleontological inventory of the site, preparing a map and database showing the distribution of 14 individual localities, identifying potential natural and human threats, and providing recommendations for stabilization and preservation. We have assisted with funding to develop a research station on site, and two buildings were constructed for this purpose in 2005. In addition, we are developing an interpretive plan following the guidelines that are used by the U.S. National Park Service to identify the primary interpretive themes; this will aid in developing plans for exhibits and brochures that will help to educate the local people, school students, and visitors.
Maria G. Moiseeva
Geological Institute, Russian Acad. Sci., Moscow 119017, Russia
Koryak Flora comes from the Upper Subformation of the Koryak Formation in the Emima-Ilnaivaam interfluve (Koryak Highland) in North-eastern Russia. This flora reflects predominantly broad leaved – coniferous vegetation and comprises about 33 species, with Metasequoia occidentalis, Corylites beringianus and several species of Trochodendroides being the most abundant. Other characteristic plants of this flora are Equisetum arcticum, Onoclea hesperia, Mesocyparis beringiana, Glyptostrobus nordenskioldii, Elatocladus talensis, Haemanthophyllum cordatum, Sparganiophyllum sp., Cissites pekulneensis, C. hermanii, Nyssidium arcticum, Rarytkinia amaamensis, Ettingshausenia raynoldsii, Celastrinites septentrionalis, Liriophyllum aeternum, Amaamia tshucotica, Platimelis platanoides etc. Middle Koryak Subformation as well as deposits overlying the plant bearing beds yield marine mollusk fossils. Correlation of plant-bearing and marine deposits allows to date the Koryak Flora as late Maastrichtian.Based on plant fossils distribution in localities, three plant communities are recognized: semi-aquatic plant community, mixed coniferous-broadleaved flood-plain forest and coniferous forest inhabited hill slopes. Semi-aquatic plant community is represented by Equisetum, Haemanthophyllum and possibly herbaceous Sparganiophyllum. The majority of the Koryak plants probably belongs to a mixed coniferous-broadleaved flood-plain forest with predominance of Taxodiacea (Glyptostrobus, Metasequoia), Cupressaceae and angiosperms Corylites and Trochodendroides. Dicots Ettingshausenia, Celastrinites, Cissites and Rarytkinia are less numerous in this community. Ferns (Onoclea, Coniopteris) and herbaceous plants (Sparganiophyllum) probably formed an understorey of this forest. Information on plant communities from uplifted places is very limited. Plant megafossils belonging to Pinaceae are rare and fragmentary. This probably reflects their long transportation. However, palynological data (D. Jolley pers. comm.) shows that representatives of this family were numerous. This implies that a coniferous forest dominated by Pinaceae plants was widespread in uplifted places situated at some distance from the Koryak sedimentary basin.In Northern Alaska, the Campanian (?) – Maastrichtian Late Kogosukruk Flora from the Prince Creek Formation is characterized by a predominance of Parataxodium wigginsii and Equisetites, whereas angiosperms (Quereuxia angulata, Carpolithes sp.) are very rare. Although this flora is of the same (or similar) age as the Koryak Flora, it differs from the latter significantly in taxonomic composition and much lower diversity (only 13 species) and probably reflects coniferous vegetation existed in a cooler climate than that experienced by the Koryak Flora.The late Maastrichtian Koryak Flora shows the closest similarity to the Sagwon 1 Flora from the uppermost Prince Creek Formation in Northern Alaska. This flora, first collected by Jack Wolfe in early fifties, is most likely of Danian age. 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 genera Mesocyparis, Haemanthophyllum, Sparganiophyllum, Phragmites, Rarytkinia, Ettingshausenia, Celastrinites and Cissites. This implies that the Koryak Flora possibly sourced many of the Sagwon 1 taxa as the Paleocene warming took place.
Jeffrey A. Myers1, Diane M. Erwin2 and Howard E. Schorn2
1Department of Earth Science, Western Oregon University, Monmouth, OR 97361, USA
2University of California Museum of Paleontology, 1101 Valley Life Sciences Bldg. University of California, Berkeley, CA 94720-4780, USA
Early Miocene and younger paleofloras of the Far West comprise the most stratigraphically complete, widely-distributed, and best dated paleobotanical sequence spanning the Neogene in North America. Assemblages younger than 24 Ma are abundant from the Cordillera to the Pacific, from Mexico to Alaska. Many are interbedded with well-dated and correlated volcanics, co-occur with mammal fossils, and have been magnetically correlated. While leaf impression floras are best known, permineralized plant organs, silicified wood, and pollen have been studied locally, as well. The sheer abundance and wide distribution of these paleofloras provides an opportunity to examine in detail the biostratigraphy, paleoecology, and vegetational dynamics of plant communities during a period of time that saw the rise of the modern polar-regulated Earth and the establishment of modern plant distributions and community structure.While most of these floras have appeared in the literature in some form, many are in critical need of revision. Recent chronological, geological stratigraphic data remain difficult to access or unknown to the paleobotanical community, greatly limiting the resolution of new studies. We will compile and update published and unpublished taxonomic, chronological, and depositional/ecological data from Neogene paleofloras extending from central Washington State through northern California/Nevada. A major focus will be the compilation of flora-by-flora presence/absence data for abundant, widely distributed indicator taxa, particularly conifers, that will help provide a detailed picture of regional climatic, ecological, and floristic changes during this critical interval of time.
Aaron D. Pan1 and Bonnie F. Jacobs2
1Department of Geological Sciences, Southern Methodist University, Dallas, TX, 75275-0395, USA
2Environmental Science Program, Southern Methodist University, Dallas, TX, 75275-0395, USA
The African palm fossil record, though limited, provides enough data to outline palm evolution from the Late Cretaceous through the Neogene. While some pollen attributed to palms is reported from the Aptian (125 – 112 Ma), the earliest definitive record for the family in Africa is Campanian (83.5 – 70.6 Ma). Palms diversified 83.5 – 65.5 Ma and became widespread along the West and North African coasts. A notable species turnover event and decline occurs at or near the Eocene-Oligocene boundary (33.9 Ma). The Neogene plant macrofossil record documents yet fewer palm taxa, and most of the genera present occur in Africa today. Currently, the African palm flora is less diverse than those of tropical South America or Southeast Asia. The reason for this disparity is not fully understood, but based upon the fossil record it is likely that Paleogene extinctions had a greater impact on modern diversity than Neogene extinctions, which were hypothesized to have been significant as a result of Miocene or Pleistocene climatic deterioration. Recently documented palm leaves, petioles, and flowers from the Late Oligocene (28 - 27 Ma) of northwestern Ethiopia demonstrate an abundance of palms in some communities at that time. Interestingly, all of the taxa identified thus far are from extant genera occurring in Africa today. The fossils represent the earliest record of the African endemic rattan Eremospatha (Calamoideae) and the earliest African record of Hyphaene (Coryphoideae).
Judith Totman Parrish
University of Idaho, Moscow, ID 83844-3025, USA
Wolfe’s work in paleobotany is well known and further documented at this meeting. What is perhaps not so well known is his overall impact on the field of paleoclimatology, particularly pre-Quaternary paleoclimatology.
Wolfe made at least the following important contributions: Quantitative estimates of mean annual temperature and other paleoclimatic parameters from angiosperm leaves. Until the last decade or so, this was the only reliable quantitative information available for terrestrial regions. Not only did this have a profound influence on the interpretation of terrestrial paleoclimates, this work provided information against which the more-complex terrestrial isotopic record could be calibrated with respect to temperature, in addition to providing data for comparison with the marine record.
Quantitative estimates of climate from forest structure. Wolfe documented the dependence of forest structure in several regions on mean annual and mean annual range of temperature, and found that structure is independent of the taxa in the forest. Although this general concept was not new, Wolfe quantified the climatic constraints on each forest type. His nomogram proved to be robust enough to apply to fossil forests.
The importance of evolution in assessing the paleoclimatic information in plants. Wolfe was a leader in pointing out that if fossil taxa are to be used as paleoclimatic indicators, their reliability is heavily dependent on the taxonomic level, and that the use of nearest-living relatives in effect flies in the face of evolutionary change.
The importance of sample provenance in paleoclimatic analysis. Wolfe was among the first to emphasize the importance of incorporating sample provenance into paleobotanical analysis. Even though he himself did not emphasize taphonomic processes, the taphonomic aspects of collections, and the influence that taphonomy has on the reliability of the information, is an undercurrent running through most of his work. While others working on taphonomy concentrated on taphonomic effects on community structure, paleoecological interpretation, and so on, his work, particularly in collaboration with Spicer, was unusual in explicitly showing the importance of accounting for taphonomic processes in paleoclimate studies.
Statistical methods. Wolfe was a leader in the application of complex multivariate analysis to paleoclimate work.
Academic scions. Although Wolfe did not work in an academic setting during most of his career, he nevertheless turned out an extraordinary set of postdocs, most notably Spicer, Wing, and Upchurch. These three paleobotanists have a minimum collective total of 110 cited publications in the last 25 years, or more than 4 per year, an extraordinary record. Many of these publications are ground-breaking in paleoclimatology in their own right, and these workers have significantly extended his work into interdisciplinary studies among paleobotanists and other paleontologists and geologists.
Kathleen B. Pigg1 and Melanie L. DeVore2
1Arizona State University, Tempe, AZ 85287-4501, USA
2Georgia College & State University, Milledgeville, GA 31061, USA
Although David Dilcher and Jack Wolfe were born on the same summer day in 1936, their many contributions to paleobotany have been a study in contrasts. One example is their systematic paleobotanical studies of North American Eocene floras. Much of Dilcher's systematic work has focused on plants of the megathermal Claiborne Formation of Tennessee and Kentucky while Wolfe's contributions have centered on elements from the "upland" temperate floras of the Okanogan Highlands of British Columbia and Washington State. Because the geological histories of southeastern and northwestern North America differ dramatically, there are sharp contrasts between not only floristics but also the types of evolutionary questions that could be addressed. Work of Dilcher and his students has been pivotal in our understanding of the evolution of lauraceous plants, oaks and legumes, while that of Wolfe and colleagues has contributed to temperate plant evolution of such groups as the birches, maples and Rosaceae. These two researchers have set the stage, and the standard, for subsequent taxonomic work in these areas and provided training and inspiration to many students and colleagues who continue to make contributions today.
Mihai E. Popa
University of Bucharest, Faculty of Geology and Geophysics, Laboratory of Palaeontology, 1, N. Balcescu Ave., 010041, Bucharest, Romania, Tel: +4(021) 314-3508 ext. 128, Fax: +4 (021) 318-1557.
Genus Cycadopteris is represented by uni- or bipinnate fronds having alethopteroid, coriaceous, hypostomatic pinnules with the abaxial margin thickened of folded, presenting a depressed area where stomata occur. The primary rachis is not forked, bearing often pinnules directly inserted to it. Barale (1982) gave an extended study on this genus, rer-assessing its systematics, demonstrating that the denomination Lomatopteris is a junior synonym of Cycadopteris. This leaf type probably belongs to seed ferns, most probably to Corystospermales.
Andrae (1855) defined Sphenopteris obtusifolia as a new species from Anina (Steierdorf), a Lower Jurassic plant locality from Romania. New material collected by Semaka (1972), with clear abaxial foldings, assigned to Sphenopteris obtusifolia by Semaka, was re-examined briefly and assigned to Cycadopteris by Popa (2000), who compared it with Cycadopteris jurensis and Pachypteris gradinarui. New structural aspects are now taken into consideration, permitting a more detailed reassessment of the taxonomic status of Cycadopteris obtusifolia, as well as a review of the status for all species of genus Cycadopteris.
Andrae, C., 1855. Fossile Pflanzen der Tertiarformation von Szakadat und Thalheim in Siebenburgen und der Liasformation von Steierdorf im Banate. Zeitschr. Naturwiss. Halle: 201-207.
Popa, M.E., 2000. Early Jurassic land flora of the Getic Nappe, University of Bucharest, Bucharest, 258 pp. PhD thesis.
Semaka, A., 1972. Einige Bemerkungen zu Sphenopteris obtusifolia Andrae. Palaontologische Abhandlungen B, 3: 861-866.
Department of Geological Sciences, University of Oregon, Eugene OR 97403, USA
Mallee is a distinctive Australian plant formation of small trees, such as Eucalytus viridis, in semiarid regions between subhumid woodlands of the Great Dividing Range and arid shrublands of the outback. Traveling west from eastern Australia, the height of woody vegetation declines with declining mean annual precipitation, unlike the situation in the Americas, Africa and Eurasia, where sagebrush shrublands and humid woodlands are separated by intervening grasslands. In Australia, soils become increasingly silty, change hue from red to yellow, and have shallower calcic horizons from wet Alfisols to dry Aridisols, but elsewhere clayey, red, deep-calcic soils of woodlands (Alfisols) are divided from yellow, silty, shallow-calcic soils of sagebrush (Aridisols) by clayey, brown, crumb-structured, intermediate-depth-calcic soils of sod grasslands (Mollisols). Studies of paleosols demonstrate Alfisols, Aridisols and intergrades like those of modern Australia in Eocene and older rocks of the Americas, Asia and Africa. Paleocene and Eocene paleosols in southwestern Montana and central Utah have shallow calcic horizon, cicada burrows and small-mammal faunas like soils of sagebrush. Late Eocene (35 Ma) advent of grasslands in southwest Montana and South Dakota can be inferred from fine root traces, granular soil structure, abundant grass phytoliths and cursorial mammals in paleosols at a time of warm subhumid paleoclimate inferred from paleosol alkali depletion and deep calcic horizon. Early Oligocene drying episodes resulted in expansion of sagebrush, not grasslands. Advent of the first crumb-structured, dark paleosols (Mollisols) of sod grasslands in the early Miocene (19 Ma), and of the first deep-calcic Mollisols of tall grasslands in the late Miocene (7 Ma) were also at times of warmer and wetter than usual paleoclimate. Grasslands are not direct biological responses to climatic drying, but coevolved ecosystems of grasses and grazers, which did not coevolve to the stage of sod grasslands in Australia until human introduction.
Dana L. Royer1 and Peter Wilf2
1Wesleyan University, Middletown, CT, 06459, USA
2Pennsylvania State University, University Park, PA, 16802, USA
Jack A. Wolfe and David L. Dilcher are well known for their many breakthroughs developing and applying paleoclimate proxies based on the sizes and shapes (physiognomy) of fossil angiosperm leaves. One method advanced by Wolfe is leaf-margin analysis, which correlates mean annual temperature (MAT) with the proportion of woody dicot species in a flora that have untoothed leaf margins. More recently, Wolfe developed the CLAMP method, which correlates a range of climatic variables including MAT with ~30 leaf character traits; CLAMP clearly demonstrates the potential of multivariate leaf physiognomy to estimate paleoclimate. In the spirit of this previous work, we and collaborators, including Dilcher, have developed a new method called digital leaf physiognomy (Huff et al., 2003; Royer et al., 2005). Digital leaf physiognomy adopts a multivariate approach like CLAMP and is based on a suite of continuous variables that can be computed with very little human error. Variables include, but are not limited to, number of teeth and tooth area, and derived variables such as tooth area / perimeter and other ratios. To test the new method, we analyzed 17 living floras from the US East Coast and Panama (Royer et al., 2005); multiple linear regressions for predicting MAT based on digital leaf physiognomy are associated with less error (±2°C) in our data set than both leaf-margin analysis and CLAMP (±3°C). These results suggest that it now may be possible to reconstruct MAT from fossil plants with greater accuracy than has been possible before. We are currently exploring the application of digital leaf physiognomy to the fossil record and expanding our calibration set to include more tropical sites.
In parallel with these studies, we are also investigating the use of digital leaf physiognomy to reconstruct aspects of leaf ecology. Leaf mass per area and foliar nitrogen content are important ecological variables that provide insight into how fast nutrient resources are turning over but which cannot be computed directly from fossil leaves. In our calibration set (Royer et al., 2005), tooth area variables correlate significantly with leaf mass per area and foliar nitrogen content; we are also exploring correlations between petiole dimensions and leaf mass. These preliminary results suggest that a method for reconstructing leaf mass per area and foliar nitrogen content from fossil leaves may be possible in the near future.
Robert A. Spicer
Earth Sciences Department, Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR), The Open University, Milton Keynes, MK7 6AA, UK
One of Jack Wolfe’s major scientific contributions was the recognition and demonstration, through multivariate statistical techniques, that leaf form is the result of a complex interplay of multiple environmental factors (mostly, but not exclusively, climate) triggering developmental responses orchestrated by the genome, itself the product of environmentally influenced selection. Paleoclimate variables may be deduced from fossil leaf physiognomy via training sets (calibration data) derived from modern vegetation growing under known climatic conditions. Wolfe named the technique CLAMP (Climate Leaf Analysis Multivariate Programme) at the heart of which is the multivariate ordination technique known as Correspondence Analysis. The training set samples are ordered relative to one another in multidimensional space based on numerical coding of leaf forms displayed by a minimum of 20 species of woody dicots found in those samples. The pattern, in particular the ordering, of the samples in this physiognomic space constrains the position vectors for each climate variable, and each vector can be calibrated from the observed climate at the sample sites. Fossil assemblages, scored for physiognomic traits in the same way as the modern training (calibration) sets, are positioned in physiognomic space passively, and the position of the fossil sample, when projected on to the calibrated vectors, yields paleoclimatic estimates for the fossil site in question.
Apart from variables intrinsic to the fossil assemblage such as taphonomic filtering (often difficult to quantify), CLAMP uncertainties are functions of:
the woody dicot species diversity at each of the training sites,
the extent to which the full range of leaf morphologies (e.g. sun and shade leaves) is scored within each of the training samples,
the quality of the observed climatic data,
and the degree to which the shape of physiognomic space can be effectively summarised by a straight line vector.
In CLAMP a minimum of twenty species of woody dicots at each site is required and the full range of observed morphologies scored. This, coupled with sampling spatially close to, and at the same altitude as, a climate station with records of at least 30 years, maintains uncertainties at an acceptable level for the standard training sets used to date. Details are published in numerous papers and on the CLAMP website:
The issue of whether the structure of physiognomic space can be effectively summarised by straight line vectors is more problematic. As more sites are added to the training sets straight line climate vectors become increasingly inappropriate, demanding instead a nearest neighbour approach. A new CLAMP website with all training set raw data score sheets is introduced.
Ruth A. Stockey1 and Gar W. Rothwell2
1Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9 Canada
2Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA
An extremely species rich Lower Cretaceous flora dating from the Hauterivian-Valanginian boundary has been discovered in marine sediments at Apple Bay, Vancouver Island, British Columbia, Canada. Large numbers of well-preserved permineralized plants including conifers, cycadophytes, vascular cryptogams, bryophytes, and fungi are preserved in calcareous nodules and the surrounding sediments. Many of these are small, delicate plants, rarely preserved as fossils, and together they provide a detailed snapshot of west coast North American vegetation shortly before the appearance of flowering plants in the fossil record. Fossils include gametophytes of three mosses and one leafy liverwort, shoots of Lycopodium, Selaginella, and Equisetum. There are large numbers of ferns from diverse families represented by rhizomes, roots, rachides and sporangia with well-preserved in situ spores. Ferns include a small osmundaceous rhizome with attached stipe bases, and fertile pinnae of Osmunda, with clusters of large sporangia that contain spherical, trilete, tuberculate spores most closely resembling those of O. regalis. Mesarch solenostelic ferns of three types show affinities to Gleicheniaceae, Schizaeaceae, and Dipteridaceae. Two types of exarch solenostelic rhizomes with attached rachides and roots are similar to Solenostelopteris and Loxomopteris but probably represent new genera. Radial exindusiate sori that are borne under veins on raised receptacles, consist of about 20 sporangia with a narrow stalk, a vertical annulus, and a well-defined stomium are intermediate between modern species of Pteridaceae and Cyatheaceae s.l. In situ tetrahedral spores are trilete with prominent angles and an equatorial flange, and compare closely to the genus Pterozonium of the Pteridaceae, Subfamily Taenitidoideae. Other fertile pinnules are assignable to Cyathaea of the Cyatheaceae s.s., Dicksoniaceae, and Matoniaceae. A combination of compressed and permineralized dipteridaceous leaves with reticulate veins and freely ending veinlets and attached sporangia that are sunken into the areolae, represent the first evidence of permineralized Hausmannia. Epidermal characters including stomata, sclerenchyma sheathes surrounding the vascular bundles, short-stalked sporangia interspersed with paraphyses and tetrahedral, trilete spores document that Hausmannia is clearly distinct from both Dipteris and Cheiropleuria. Numerous cycadophyte pinnae are present and pinaceous and taxodiaceous conifers are especially abundant. The earliest fossil evidence of Pseudotsuga-like and Picea-like leaves as well as several unknown pinaceous taxa reveal a large diversity of Pinaceae. Pollen cones and leaves of taxodiaceous conifers represent at least two new genera: one with abaxial and one with adaxial pollen sacs. This unexpectedly diverse Lower Cretaceous flora represents a mixed coniferous forest with a few cycadophyte species, and a rich ground cover of pteridophytes, bryophytes and fungi.
Ge Sun1, Michael Akhmetiev2, Lina Golovneva3, Eugenia Bugdaeva4, Harufumi Nishida5, Tatyana Kodrul2, Chunlin Sun1, Yuewu Sun1, Chen Quan1, Kirk Johnson6 and David Dilcher7
1Research Center of Paleontology, Jilin University, Changchun 130026, China
2Geological Institute of RAS, Moscow 109017, Russia
3Komarov Botanical Institute, RAS, St.-Petersburg, 197376 Russia
4Institute of Biology & Pedology, FEB RAS, Vladivostok, 690022, Russia
5Chuo University, Tokyo 112, Japan
6Denver Museum of Natural Sciences, Denver, CO-80205, USA
7Florida Museum of Natural History, University of Florida, Gainesville, FL32611-7800, USA
Through cooperative research projects, in Jiayin area of Northeast China during 2002-2005, Late Cretaceous mega-fossil plants were collected along the Heilongjiang River, China, and over 40 species of 30 genera recognized. The plants were collected mainly from Upper Cretaceous Yong’ancun Formation and Taipinlinchang Formation exposed in this area. They include horsetails: Equisetites sp., ferns: Asplenium dicksonianum Heer, Arctopteris sp., Cladophlebis sp.; ginkgoales: Ginkgo pilifera Samylina, G. adiantoides (Ung.) Heer, G. sp.; conifers: Larix sp., cf. Podocarpus tsagajanicus Krassilov, Pityospermum minutum Samylina, Pityophyllum sp., Cupressinocladus sveshnikovae Ablajev, C. sp., Parataxodium sp., Taxodium olrikii (Heer) Brown, Sequoia sp., Metasequoia disticha (Heer) Miki, Glyptostrobus sp., Xenoxylon latiporosum (Cramer) Gothan; and angiosperms: Trochodendroides arctica (Heer) Berry, T. smilacifolia (Newb.) Krysht., Platanus densinervis Zhang, P. sinensis Zhang, "Platanus" raynoldsii (Newb.) Brown, Platanus? sp., Pterospermites heilongjiangensis Zhang, Vibernum cf. contortum Lesq., Nordenskioldia cf. borealis Heer, Arthollia orientalis (Zhang)Golov., Celastrinites sp., Beringiaphyllum? sp. "Pistia" corrugata Lesq., Quereuxia angulata (Newb.) Krysht., etc. The flora is characterized by ferns (ca.12.5%), ginkoales (ca.7.5%), conifers (ca.35%) and angiosperms (including some aquatic taxa) (ca.45%). Some taxa previously identified by Zhang (1983) are systematically revised by the present authors. Two floristic assemblages of the flora can be recognized. They are (1) the Yong’ancun Assemlage (Parataxodium-Quereuxia Assemblage), and (2) the Taipinglinchang Assemblage (Metasequoia– Trochodendroides-"Pistia" Ass.) which is more abundant and dominated by angiosperms. Paleoclimatically and paleoecologically, the flora is dominated by thermophilous and hydrophilous taxa, e.g. the conifers consist of evergreen (Sequoia, Cupressinocladus, etc.) and deciduous (Larix, Paratadium, Taxodium, Metasequoia, Glyptostrobus) types, and also there are abundant deciduous broad-leafy angiosperms. These appear to demonstrate warm temperate vegetation consisting of both evergreen and deciduous taxa.This then implies a warm temperate to temperate climate. These new data are helpful for a better understanding the biotic and paleoenvironmental backgroud in the Heilongjiang (Amur) River area during the middle-late Late Cretaceous, including the nature of the food resources for dinosaurs (e.g. Hadrosauria) and other animals. These animals are also helpful in our study of the larger biotic and geological events happened near the time of the K/T boundary in this area.
*Supported by NSFC Proj. 30220130698, 30370096, 30511120003(NSFC-RFBR) and the Programme of Introducing Talents of Discipline to Universities, China
Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, No.20 Nanxincun, Xiangshan, Beijing 100093, P. R. China
China is a large country with abundant recent and fossil plants. The climate of China is influenced strongly by the Asian monsoon system, itself largely a product of the altitude, size and position of the Tibetan Plateau. Physiognomic studies of fossil plants in China are of great importance to further understand evolutionary history of Chinese vegetation and climate in regional and global senses. Early physiognomic studies on Tertiary floras in China using leaf margin analysis (LMA) approach began in the mid-1980s. A total of 48 species of a Miocene Xiaolongtan flora from Kaiyuan (23º48’N, 103º11’E), Yunnan, was investigated (Zhou, 1985), showing that the percentage of entire-margin species (PEMS) of the flora is 79% and that mean annual temperature (MAT) is about 20°. It is also indicated that Kaiyuan region belonged to a southern subtropical zone climate during the Miocene (Zhou, 1985). Foliar physiognomy of a Paleocene flora in Altay (46º34’--46º45’N, 88º87’--87º40’E, see Ye et al., 2001), Xinjiang Autonomous Region was studied (Li, 1986). PEMS of the Altay flora is 33% (40 species was used), indicating a warm temperate climate with an MAT of 12°. Yang (1988) studied 129 species of the physiognomic characters of a Miocene Shanwang flora (36º32’N, 118º43’E) from Shandong. PEMS of Shanwang flora is about 38%, indicating that the palaeoclimatic zone of Shanwang during the Miocene is between temperate and subtropic zone with an MAT of 11.5°. There are two floras (46º10’N, 129º15’E) from Yilan County, Heilongjiang (He, 1989; He and Tao, 1994). For the early Eocene flora from Yilan, there are 18 entire margin species in 47 woody dicotyledons (PEMS=38.3%, MAT=13.2°). For the Oligocene flora from Yilan, there are 8 entire margin species in 26 woody dicotyledons (PEMS=30.8%, MAT=11°). Liu (1993) studied the early Pleistocene flora of Changsheling Formation (23º45’N, 106º55’E), Baise Basin, Guangxi, indicating a PEMS of 73.3% (30 woody dicotyledons) and MAT of 24° and representing the transitional zone from subtropics to tropics. It is thanks to the great support from late Professor Jack A. Wolfe and other colleagues including Bob A. Spicer and Margaret E. Collinson that Climate Leaf Analysis Multivariate Program (CLAMP) approach has been introduced to Chinese colleagues (Sun and Yang, 2000). CLAMP approach has been applied to the Tertiary floras in China to quantitatively reconstruct the palaeoclimate of some regions (Sun et al., 2002, 2003; Quan and Zhang, 2005). Meanwhile, we have initiated to apply both CLAMP and LMA approaches to the Chinese modern forests (Wang and Sun, 2002; Sun et al., 2002). The on-going work of physiognomic studies of fossil and modern plants in Yunnan and other regions of China is partially supported by National Natural Sciences Foundation of China (No.40572001).
Key words: foliar physiognomy, LMA, CLAMP, Tibetan Plateau, China
Ralph E. Taggart and Aureal T. Cross
Department of Geological Sciences, Michigan State University, East Lansing, MI 48824, USA
The source vegetation of any watershed is a complex mosaic of "patches" that reflect the interaction of the regional botanical inventory, site factors, and local disturbance history. Despite the complex of taphonomic biases that modulate the fossil record of the various components of the mosaic, analytic tools are available that permit the extraction of major paleoclimatic parameters that controlled vegetation development. In principle, disturbance is pervasive in terrestrial plant communities, but some disturbance events are of such exceptional magnitude that they can initiate ecological succession on a scale that appears, at least temporarily, to transform the local or regional vegetation mosaic. Such "macro-disturbances" can include holocaustic fires, volcanic eruptions, and extraterrestrial impacts. Seral recovery stages following major disturbances may not be suitable for reliable reconstruction of paleoclimate. The Mixed Mesophytic forest phases that are characteristic of forest recovery in the Mixed Coniferous and Evergreen Broad-leaved forests of the Neogene of the northern Intermountain region are a case in point.
The initial or pioneering seral stages typically can be recognized on the basis of floristic and quantitative criteria. In the Neogene of the Western Interior, such pioneering seres are grass-forb dominated, in contrast to Pteridophyte-dominated assemblages of the Paleogene and Mesozoic. The transitory nature of pioneering seres represents a temporal bias that often precludes recognition where adequate stratigraphic/sampling resolution is lacking. Later recovery stages typically persist longer, but such communities are much more characteristic of the normal vegetation mosaic and thus may be difficult to recognize using floristic criteria.
Some simple modeling exercises suggest that palynological recognition of seral stages is largely confined to the interior of a disturbed area and proximal to the disturbance boundary, irrespective of the geographic extent of the disturbance. This theoretical model is supported by numerous case studies in the Intermountain Tertiary. An appreciation of the spatial limits for the recognition of post-disturbance vegetation provides insight into the geographic distribution of the so-called "fern spore abundance anomaly" associated with the K/T boundary event.
Edith L. Taylor*, Patricia E. Ryberg and Thomas N. Taylor
Dept of Ecology & Evolutionary Biology, Natural History Museum and Biodiversity Researh Center, University of Kansas, Lawrence, KS 66045-7534, USA
Permineralized plants from the central Transantarctic Mountains (CTM) region of Antarctica have provided detailed information on reproductive structures in both glossopterid and corystosperm seed ferns. Fossil wood, which can provide proxy climate information, is also common in this area, both in the peat and in fluvial rocks. Permian wood occurs in the permineralized peat collected on Skaar Ridge in the upper Buckley Formation (Late Permian). Triassic wood occurs in permineralized peat and coeval sandstones in the upper Fremouw Formation (Middle Triassic). The peat preserves cellular detail and thus provides information on tree ring structure in woody plants, as well as details of floral diversity and plant growth.
During both periods, the Earth was in a greenhouse phase, with temperatures in polar regions sufficient and even favorable for plant growth. Paleogeographic reconstructions suggest that the CTM floras were growing above 70°S in the Triassic and above 75-80°S in the Permian. Triassic tree rings average 1.69 mm in width, and Permian ones 2.33 mm. These differences may reflect the fact that the Triassic wood included more mature axes, and that there were very few Permian specimens analyzed, due to poor cellular preservation. Although ring width is similar from both time periods, floral diversity is not. Late Permian floras throughout Gondwana were of very low diversity; in Antarctica some sites show up to 90% coverage for glossopterid leaf types (i.e., Glossopteris and Gangamopteris). In contrast, the Middle Triassic flora is much more diverse, with all major groups of vascular plants represented, including five families of seed plants.
Permian and Triassic woods both exhibit a large amount of earlywood and very little latewood, suggesting a long, favorable growing season and a very short transition to dormancy. At these paleolatitudes, the plants must have experienced 24 hours of light during the summer. Minimal change in radial cell diameter across individual rings and the small amount of latewood appears to be due to a rapid transition to low light levels at the end of the growing season. Mean sensitivity, which measures the difference in ring widths from one year to the next, suggests that there was some climatic variability from year to year. Permian woods were all classified as sensitive, but only 52% of the Triassic woods fell into this category. Tree ring analysis data will be presented and discussed in relation to light regime at these high paleolatitudes.
G.R. Upchurch, Jr1, D.J. Beerling2 and B.H. Lomax2
1Department of Biology, Texas State University, San Marcos, TX 78666, USA,
2Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
Since publication of evidence for the impact of an asteroid or comet on Earth at the end of the Cretaceous, paleobotanical studies of the Cretaceous-Tertiary (K-T) boundary have provided important evidence on short-term and long-term environmental change. North America has played a central role in studies of the K-T boundary because it contains numerous stratigraphic sections that preserve both terrestrial floras and geochemical/mineralogical evidence for a terminal Cretaceous bolide impact. These sections, which range from New Mexico to Canada, represent paratropical to temperate biomes and provide important constraints on proposed environmental changes through their preserved palymomorphs, leaf megafloras, and dispersed leaf cuticles.
Palynology provides major evidence for widespread terrestrial mass-mortality at the K-T boundary. Cretaceous palynomorphs abruptly disappear from the stratigraphic record at the level of the K-T boundary clay. Immediately above this disappearance is an anomalous abundance of fern spores (or fern spike), with individual assemblages dominated by a single spore type. The fern spike is followed by the re-establishment of woody plant dominance in palynofloras and the appearance of Tertiary taxa. Leaf megafloras and dispersed leaf cuticles show a comparable pattern of change. Vegetation change at the K-T boundary has been compared to primary succession in the modern wet tropics, but it may have been of longer duration.
Leaf floras, stable carbon isotopes, and biogeochemical models indicate significant long-term changes in climate associated with the K-T boundary. Noteworthy is evidence for an increase in precipitation following the terminal Cretaceous event, which includes an increase in leaf size in early Paleocene floras. Foliar physiognomy of leaf megafloras provides mixed evidence on long-term temperature trends, with the exact pattern dependent on the flora investigated and the analytical method. Multivariate analysis of leaf physiognomy, combined with reconstructions of atmospheric pCO2 using stomatal index, suggest significant temperature increases associated with major (>4x) increases in atmospheric pCO2. Stable isotopic analysis of bulk terrestrial carbon indicates that the negative isotopic anomaly associated with the K-T boundary starts at the level of the fern spike and continues well into vegetation recovery. This indicates that the isotopic anomaly—taken as evidence for the release of biologically fixed carbon to the atmosphere—was due to long-term alterations of the global carbon cycle, rather than biomass burning at the K-T boundary. Biogeochemical modeling indicates that terrestrial biomass underwent a significant increase due to increases in temperature, precipitation, and atmospheric pCO2 following the terminal Cretaceous event. This implies that terrestrial vegetation helped stabilize atmospheric pCO2 following vaporization of carbonate rock by the Chicxulub impact.
Torsten Utescher1, Volker Mosbrugger2, David L. Dilcher3, Vladimir Bozukov4, Dimiter Ivanov4 and Abdul R. Ashraf5
1Geological Institute, Bonn University, Bonn, 53115, D
2Seckenberg Research Institute and Natural History Museum, Frankfurt/M., 60325, D
3Florida Museum of Natural History, Gainesville, FL 32611-7800, USA
4Institute of Botany, Bulgarian Academy of Sciences, Sofia, 1113, BG
5Institute for Geosciences, Tübingen University, Tübingen, 72076, D
A climate record for the Central European Cenozoic recently reconstructed from macrofloras using the Coexistence Approach (Mosbrugger and Utescher, 1997) reveals climate change during the last 45 My (Mosbrugger et al., 2005). The climate evolution is characterized by continental cooling leading from almost tropical conditions in the middle Eocene to a temperate climate in the latest Pliocene. Climate variability is reflected by non-proportional change of mean annual temperature, winter temperature, summer temperature, and mean annual precipitation.
Here, climate data obtained for the single macrofloras are analyzed in the context of present-day climate. The four climate variables calculated are combined in order to identify regions on the Northern Hemisphere that can be regarded as climatically equivalent to the inferred paleoclimate conditions. These regions, shifting in time, are visualized on maps. It is shown that present-day climate equivalents to our Cenozoic data commonly are restricted to rather delimited areas. In several cases, there existed fossil climates / combinations of climate variables that are not realised at present. Climate equivalents of the Central European middle Eocene today exist in Southeast Asia and the northern part of Central America. Reference regions for the Mid-Miocene Climate Optimum are northern Florida and south China while present-day climates of eastern Sichuan and Virginia reflect the Pliocene conditions of Central Europe. To study regional effects, climate data calculated for Oligocene to Miocene macrofloras from Eastern Europe (Paratethys; Bulgaria) are included.
The present approach allows for an easy identification of climate type and vegetation cover corresponding to the reconstructed paleoclimate conditions. Further on, a set of climate data can be extracted for each reference region identified that in turn can be used to calibrate climate variables obtained from the Coexistence Approach by modern climate. This calibration may lead to a narrowing of coexistence intervals of up to 50%, thus helping to improve the resolution of the method.
Mosbrugger, V., Utescher, T., 1997. The coexistence approach – a method for quantitative reconstructions of Tertiary terrestrial palaeoclimate data using plant fossils. Palaeogeography, Palaeoclimatology, Palaeoecology 134, 61-86.
Mosbrugger, V., Utescher, T., Dilcher, D.L., 2005. Cenozoic continental climatic evolution of Central Europe. Proceedings of the National Academy of Sciences 102(42), 14964-14969.
Maria Patricia Velasco de León
Facultad de Estudios superiores Zaragoza. UNAM. Mexico D: F. 09230
In Mexico paleoecological studies using angiosperms leaves are scarce due to the fact that this type of beds are poorly known and/or the leaves are not so abundant or are not well-preserved at all. In this work paleoclimate was inferred of localities of the State of Hidalgo, Santa Maria Amajac and SancTorum through the foliar analysis of leaves associations of fossil leaves sampled there using the CLAMP program.
The area under studio is located within the geomorphologic province of the Neovolcanic-Axis. This elevation started its activity since the Oligocene and continued through the Pliocene, resulting in the deposition of igneous rocks, ashes and sedimentary material carried by the Amajac river, and in the accumulation of the sediments of the Atotonilco El Grande Formation, with 151.3 m in thickness and a maximus surface of 80,500 m2. with six types of facies; those corresponding to the marginal zone of the locality of Santa Maria Amajac, are basically composed of fine-grained sandstones, which characterize the inundation basin, exhibiting cross-lamination, normal grading, desiccation marks and abundant impressions of Quercus leaves though not very well-preserved, together with scarce impressions of Platanus, Populus y Cercocarpus; in contrast to better-quality fossils sampled in the silt-shale facie, showing fine-thin strata ranging from 20 to 30 cm. The distant zone of the lake (Sanctorum) is characterized by facies with a peelitic texture. This deposit is finely laminated and has a thickness ranging from 1 to 3 cm, with an abundant faunistic content and presenting a greater diversity of leaves (Platanus, Salíx, Populus and in less proportion, Quercus, Leguminoseae, Juglandaceae, Moraceae and Eritrina.
The leaves from both localities were revised with microscopy and Camera Lucida in order to have schemes and to separate them according to venation patterns (morphotypes). Finally, the character states were registered for each leaf type, obtaining the corresponding percentage (Wolfe, 1993). The obtained data were processed using the Canoco vertion 3.12 Program and applying the canonic correspondence analysis. Of more than 1000 collected leaves for ST locality, 33 types were identified and 30 morphotypes of Santa María Amajac, for the 31 character-states. With the values from above, MAT, WMMT, CMMT, 3DRY and MAP, according to the classification of García (1988), the expected climates for the localities are: semi -warm wet for SancTorum and template semi-wet for Santa Maria Amajac.
Friederike Wagner1, David L. Dilcher2, and Henk Visscher1
1Palaeoecology, Laboratory of Palaeobotany and Palynology, Utrecht University, 3584 CD Utrecht, The Netherlands
2Florida Museum of Natural History, Gainesville, Florida 32611
In a stomatal frequency analysis of leaf remains of Quercus nigra, Acer rubrum, Myrica cerifera, Ilex cassine, and Osmunda regalis that were preserved in precisely dated peat deposits of north-central Florida, the stomatal index decreased as a response to an atmospheric CO2 increase from 310 ppmv to 370 ppmv over the past 60 years. The observations indicate that CO2 responsiveness may occur in different canopy levels of hardwood-swamp vegetation. Apart from common woody plants, long-lived ferns of the undergrowth appear to be affected by CO2 changes. Response rates are most pronounced in M. cerifera, I. cassine, and O. regalis. The potential of these species for quantifying past atmospheric CO2 levels is assessed by a combined analysis of the well-dated buried leaf record and herbarium material collected during the past century. Leaf remains of the widely occurring species M. cerifera and I. cassine are concluded to be highly suitable for CO2 reconstructions, by which the application range of the stomatal frequency proxy is extended into the warm-temperate to subtropical realm of North America.
In all species studied, a distinct response in stomatal dimensions is associated with the general decrease of the stomatal densities. Calculations of the stomatal resistance show that this parameter increased by approximately 30% over the past 60 years. Up-scaled on genus level, the genera included in this study account for nearly 60 % of the canopy. The consistent changes in the transpiration rates due to stomatal resistance changes are supposed to have a significant effect on the local hydrology.
Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093, P. R. China
Cercis consists of one member of the basal monophyletic tribe Cercideae, which is a sister group to all other legumes or one of the basalmost clades in the Leguminosae. Therefore, the fossil history of Cercis is of fundamental importance in understanding the legume phylogeny and early diversification. New observations on four leaf impressions, formerly identified as Cercis miochinensis Hu and Chaney, from the middle Miocene Shanwang Formation of Shandong Province in eastern China have confirmed the presence of an upper pulvinus and other key architectural features. The upper pulvinus in similar specimens from this locality was previously described as a thickened petiolar part at the attachment point with the lamina. These pulvinate leaves are simple and unlobed in shape, bearing 5-7 actinodromous and branched primary veins, brochidodromous secondary veins approximately along the distal 1/2 to 2/3 of the midrib. Such features provide reliable fossil evidence for the leaves of Cercis L. from the Miocene of eastern China. Based upon the leaf architectural features, C. miochinensis and related species were compared. Combined the fossil record with modern distribution of Cercis, its biogeographic history was assessed.
Key words: Biogeography, Cercis, Leaf architecture, Leguminosae, Miocene, Shanwang Formation, Tertiary.
Elisabeth A. Wheeler
North Carolina State University, Raleigh, NC 27695-8005, USA and NC State Museum of Natural Sciences, 11 West Jones Street, Raleigh, NC 27601-1029, USA
There are fewer than 200 reports of fossil dicotyledonous wood for the whole of the Cretaceous. This presentation reviews the characteristics of the woods described to date and shows some new Cretaceous wood types from western North America. The earliest known wood types are of the phyllanthoid and platanoid/icacinoid type. These two types are the most common throughout the Cretaceous, with almost all sites with Cretaceous woods having them. In 2000, Jack Wolfe located what is likely the locality for the type species of Paraphyllanthoxylon, P. arizonense Bailey. Some two dozen logs, most close to 1 m in diameter, were easily located. All known Aptian-Albian and Cenomanian Paraphyllanthoxylon of western North America were trees. One species of Paraphyllatnhoxylon, P. marylendense Herendeen, is Lauraceae, but the familial affinities of the others are not established. A thorough review of the icacinoid / platanoid woods is needed. In North America, the bulk of Cretaceous woods are Campanian – Maastrichtian. Not surprisingly, there is greater diversity in wood types by then, and there are some with patterns characteristic of extant groups, e.g., Fagales, Malvales. Some woods have combinations of features that are extremely rare in extant trees, e.g., few, large diameter vessels and scalariform perforation plates. Most of the dicot wood types of the Cretaceous are characterized by high proportions of storage cells, either parenchyma (close to 50% ray parenchyma in some icacinoid / platanoid woods) or a ground tissue of septate fibers (phyllanthoid woods). High proportions of ray parenchyma would affect the mechanical behavior of the wood, and high proportions of parenchyma affect water storage capacity, wound responses, and production of new tissues. Isotopic analyses and estimates of the woods’ original specific gravities may provide information on growth rates and forest structure, as well as seasonality.
Michael C. Wiemann1, Bonnie F. Jacobs2, and John Kappelman3
1Center for Wood Anatomy Research, For. Prod. Lab., Madison, WI 53711, USA
2Environmental Science Program, Southern Methodist Univ., Dallas, TX 75275, USA
3Dept. of Anthropology, University of Texas, Austin, TX 78712, USA
The wood physiognomy of an assemblage of 33 fossil woods from the Chilga region of Ethiopia was used to estimate Oligocene temperature. Comparisons of the frequency of occurrence of vessel and ray characteristics indicate that the paleotemperature was some 6-9 degrees warmer than at present. Wood physiognomy cannot be used to give reliable precipitation estimates, although the data suggest that Oligocene Chilga was probably wetter than it is today.
Scott L. Wing
Smithsonian Institution, Washington, DC 20013-7012, USA
About 55 million years ago at the onset of the Eocene, the earth warmed by 4-8 ° C over a period of 10-20 ky. This sudden global warming event, called the Paleocene-Eocene Thermal Maximum (PETM), lasted approximately 100 ky and appears to have been caused by the release of ~4,500 Gt of carbon to the atmosphere-ocean system. The rapidity and magnitude of the carbon release and associated greenhouse climate make the PETM an excellent geological analog for anthropogenic global warming.
Paleobotanical work on the PETM follows from pioneering studies by Jack Wolfe and David Dilcher. Wolfe’s Leaf Margin Analysis method has been applied to floras from Wyoming, demonstrating ~5 ° C of warming during the PETM. Comparison of the Wyoming PETM floras with Paleocene and Eocene floras of the Gulf Coastal Plain studied by David Dilcher has revealed that some, but not all, of the plant species present in Wyoming during the PETM migrated there from farther south. The individualistic migration of plant taxa during the PETM is consistent with Wolfe’s long-held rejection of "geofloras" and reinforces his idea that species within local communities respond independently to climatic change through range-change, evolution, or extinction. Combined studies of megafossils and microfossils from the same deposits, an approach used by both Dilcher and Wolfe, has been key to understanding floral response to climatic change with high taxonomic and temporal resolution.
C.G. Chase1, M. R. Cecil1, and J. A. Wolfe2
1Department of Geosciences, University of Arizona, Tucson, AZ 85721-0077, USA
2Deceased, formerly of Department of Geosciences, University of Arizona, Tucson, AZ
The uplift history of the Sierra Nevada has recently become controversial, after a long period of consensus that geomorphic and other evidence required Neogene uplift of the range despite cessation of magmatic activity in the Cretaceous. Now geophysical and geochemical data have cast doubt on this concept of late uplift of the Sierra Nevada. In order to address this controversy, Eocene fossil leaves were extensively collected in an effort to determine early Cenozoic altitudes of the range. Stratigraphic and paleohydraulic studies of the Eocene river deposits which contained the leaves were conducted to better understand development of the Sierran landscape and to place the leaves in geologic context. Stratigraphic analyses of paleochannel deposits located on the northwestern slopes of the Sierra Nevada suggest that early Cenozoic landsculpting processes were variable and that Eocene river systems were capable of moving large amounts of coarse material. Such analyses contradict the conventional idea that the Sierra Nevada was characterized by low-elevation, low relief features formed by broad, low-gradient river systems prior to Neogene uplift. Material from deepest thalwegs of the ancestral Yuba River is dominated by large (cobble-sized), well-rounded clasts, suggesting that Eocene rivers had gradients sufficient to move large clasts appreciable distances. Paleo-Yuba deposits also reveal multiple episodes of downcutting and backfilling. Such variation requires a variation in stream power, something generally attributed either to surface tilting or a change in discharge. A documented shift in Cenozoic climate toward cooler, stormier conditions (Molnar and England, 1990; Wolfe, 1994) would have a great impact on discharge and, consequently, stream power. A changing climatic regime, therefore, is capable of not only explaining the episodic erosional and depositional features preserved in paleovalleys, but also of explaining changing river gradients, independent of tectonic uplift or tilting.
Timme Donders1, Friederike Wagner1, David L. Dilcher2, and Henk Visscher1
1Palaeoecology, Laboratory of Palaeobotany and Palynology, Utrecht University, 3584 CD Utrecht, The Netherlands
2Florida Museum of Natural History, Gainesville, Florida 32611
High resolution pollen analysis of mid- to late-Holocene peat deposits from southwest Florida reveals a stepwise increase in wetland vegetation that points to an increased precipitation-driven fresh water flow during the past 6000 years. The tight coupling between winter precipitation patterns in Florida and the strength of the El Niño Southern Oscillation (ENSO) strongly suggests that the paleo-hydrology record reflects changes in ENSO-intensity. For the first time, a terrestrial subtropical record well outside the Indo Pacific Warm Pool records both the onset of modern-day ENSO periodicities between ~7 and 5 ka cal. B.P. and subsequent ENSO intensification after 3.5 ka cal B.P. During the last 2 ka the observed increases in ‘wetness’ are sustained by a gradual rise in relative sea level that prevents a return to drier vegetation through natural succession.
Preliminary Comparison of Insect Herbivory and RIchness from Analysis of Insect Damage on Floras from the Middle Eocene Clarno Formation and the Early Oligocene Bridge Creek Flora of the Lower John Day Formation, Eastern Oregon
Regan E. Dunn
National Park Service, John Day Fossil Beds National Monument, Kimberly, OR 97848, USA
The Eocene-Oligocene transition (33.9 Ma) marks a well-documented major cooling event in Earth history. Effects of these cooling events are well-documented in North American fossil floras where largely paratropical and broad-leaved deciduous and evergreen forests of the Eocene were replaced with more temperate deciduous forests by the early Oligocene. These changes in vegetation types are well-represented in middle to late Eocene fossil assemblages of the Clarno Formation (~44-40 Ma) and early Oligocene Bridge Creek Flora (~34-32 Ma) of the John Day Formation located in eastern Oregon.
With the climatically induced floral changes that occurred during the Eocene–Oligocene transition, changes in insect herbivory types and diversity are also evident, indicating a minor re-organization of insect communities. I present preliminary data from three paleobotanical localities from the Clarno Formation –White Cliffs Jr., Red Gap, and John Day Gulch– quarried through census techniques, and compare insect damage types with drawer counts of specimens from the Bridge Creek Flora contained within the collections at the John Day Fossil Beds National Monument. Preliminary results of the analysis indicate an increase in the total amount of insect herbivory in the early Oligocene localities compared to middle Eocene floras, but a decrease in the richness of damage types. Insect galling is significantly more prevalent in the early Oligocene assemblages than in the middle Eocene floras, and skeletonization is significantly less prevalent in the Bridge Creek Flora than in the sites of the Clarno Formation. This preliminary analysis indicates that the Clarno Formation shares 63% of its damage types with the younger Bridge Creek Flora. The shared types include generalized hole, margin, and window feeding. Several damage types from the Clarno assemblages, both host and non-host specific, are absent in the early Oligocene floras, including blotch mines, bud-feeding, large hole-feeding (>5 mm), and specific types of skeletonization.
Beth L. Ellis1, Kirk R. Johnson1, Carol Hutton1, Richard S. Barclay2 and Marieke Dechesne1
1Denver Museum of Nature & Science, Denver, CO, 80205, USA
2Northwestern University, Evanston, IL, 60208, USA,
For the past 15 years, researchers from the Denver Museum of Nature & Science (DMNS) have collected fossil plants from sedimentary rocks in the Denver Basin, an asymmetric foreland basin that covers roughly 7,000 mi2 and preserves sediments that range in age from the Late Cretaceous to the early Paleocene. Although outcrops are extremely rare, the rocks are abundantly fossiliferous. The fossils accumulated in a diverse series of environments, ranging from coastal swamps to alluvial fans. Of the ~160 localities collected to date, 31 quarries contain at least 200 specimens that have been analyzed to the level of morphotype, totaling over 14,300 fossils and nearly 250 (dicot) holomorphotypes. Until recently, these collections were analyzed mostly on a quarry by quarry basis. Here, we present the first synthesis of the Denver Basin Flora since Knowlton (1930), showing life-size images of the holomorphotypes arranged both spatially and temporally. During the Paleocene, diversity appears to be higher in the floras that are closer to the mountains. Although the Paleocene appears to be more diverse than the Cretaceous, this reflects a collection bias and a possible preservation bias in the sampling. More than 90% of the specimens collected are of Paleocene origin. Hence, the next stage of our project will focus intensely on Cretaceous localities.
Finding Cretaceous localities in the Denver Basin that preserve the detail necessary for cross-quarry comparisons is considerably more difficult than for the Paleocene. This is partially due to the paucity of outcropping Cretaceous rocks and partially due to low relief, vegetated terrain that is difficult to map accurately. Since a significant number of fossils are uncovered in construction sites, they are difficult to place into stratigraphic context. To alleviate this problem, we created a generalized geologic map displaying the bedrock stratigraphy of the Denver basin, based on 21 published geologic maps. Next, we modeled the K-T Boundary and projected it onto the map surface. This was done by first locating the relative position of the K-T boundary within the D1 Sequence in two cored wells. We then combined the data from the 2 wells with 4 surface K-T Boundary locations and the Denver Basin subsurface well database (containing more than 700 water, oil and gas wells) to generate a K-T surface that was intersected with a digital elevation model. This map continues to be refined through pollen biostratigraphy and field observations. Because fossil plants provide direct evidence for ancient ecosystems and proxy data for ancient climates, the geologic map, sedimentary facies observations and paleobotanical data will eventually be integrated to create a series of paleogeographic maps of the Denver Basin.
Erika L. Ortiz Martìnez1 and Maria Patricia Velasco de León2
1,2Facultad de Estudios superiores Zaragoza UNAM. México, D.F. 09230
The region of Santa Maria Amajac Hidalgo, Mexico, which belongs to the Atotonilco el Grande Formation, is characterized for presenting abundant groups of different fossils ( fish, gasteropods, ostracods, insects, diatoms and angiosperms) conserved in shales and sand. Of the angiosperm Pliocene fossils collected in the region, one group of leaves prints are pointed out, since there are characterized by the presence of primary teeth of rosoide kin, third veins that form an acute angle with the second ones, weak third veins and cuadrangular areoles. A similarity with the Cercocarpus genus leaves is presented.
After practicing the clear technique of 12 present species of the mentioned genus, a basic matrix data was made in which 11 characters and 35 characters states of double state kind were registered for 40 Otu’s (11 fossils species, 12 extant species and seven Hidalgo samples). Two multivariate methods were applied to the basic matrix data: grouping and principal coordinates by using the 2.1 version of the NTSYS program, which permited to infer the presence of a new specie of Cercarpus genus in the region.
Jay H. Jones
Departments of Biology and Chemistry, University of La Verne, La Verne, CA 91750, USA
Plant cuticle varies in structure and chemistry. Cuticles generally consist of a blend of carbohydrates, waxes, cutin, and phenolics. The proportion and distribution of each is related to the chemical resistance. Cuticles that contain larger amounts of lipid, i.e. cutin and waxes, tend to be more chemically inert than those with high carbohydrate fractions. Such cuticles can be extremely stable and resistant to enzymatic and chemical degradation. Most cuticles are quite susceptible to alkaline hydrolysis, reduction with LiAlH4 as well as, the enzymatic action of cutin esterases. However, some remain intact, both chemically and anatomically for millions of years, given a mild thermal history and continuous anoxic conditions. Cuticles isolated from early land plants suggest that the oldest chemically preserved cuticles approximate the origin of the cuticle itself. In fact, cuticles are one of the most common chemically preserved and relatively little altered fossils, having been accorded coal maceral status as cutinite.
The resistance of cuticles is of interest to those studying resistance to pathogens, petrogenesis, taphonomy and paleobotany. Determining the mechanism of resistance in such a complex macromolecular system is difficult. Tegelaar conducted extensive studies on the chemical nature of selected modern and fossil cuticles. His work supported the role of ether linkages in conferring resistance to cuticles. The existence of ester linkages in resistant cuticles suggests a linkage dependant mechanism analogous to that of a limit dextran. Resistant cuticles have been shown to be susceptible to HI digestion confirming this hypothesis. Current work seeks to test this hypothesis on a broader range of materials and to apply recently developed NMR techniques for improving spectral resolution of polymeric samples.
Department of Biology, University of La Verne, 1950 Third St., La Verne, CA 91750, USA.
A preliminary paleoclimatic
assessment, of the Middle to Upper Eocene, of central Wyoming has been
made, using a small assemblage of woods from the Wagon Bed Formation.
Approaches employed include analysis of closest living relatives, the
nature of historically utilized wood characters such as diffuse vs. ring
porosity, as well as more recent and comprehensive statistical techniques.
The latter use regression derived formulas and multiple characters. The
current sample of 10 distinct forms is somewhat limiting. However, these
approaches suggest a relatively equable climate. Based on this small sample,
calculated climatic values indicate a mean annual temperature of approximately
13 degrees Celsius and a mean annual range in temperature of 12 degrees
Celsius. Other values calculated include the coldest month mean temperature
(5 degrees Celsius), and the length of the "dry" season (3.6 months).
The calculated mean annual precipitation was in excess of 279 cm. More
accurate determination of the environmental variable will be dependent
upon increasing the sample size, or the number of distinct wood types.
Current efforts are directed toward analyzing additional samples in hopes
of increasing the sample size.
Martin C. Knyf1, Amy C. Reynolds1,2 and Darren R. Gröcke1
1SIBL, McMaster University, Hamilton, Ontario, L8S 4K1, Canada
2Department of Geology, Leeds University, Leeds, LS2 9JT, UK
Research using carbon-isotope ratios (δ13C) in terrestrial organic matter has been used recently to reconstruct global climate, environments and ecology of ancient plant ecosystems. In addition, carbon isotopes in charcoal, cuticle and bulk terrestrial organic matter from stratigraphic sections have been used for correlating marine and terrestrial sequences. Although many researchers have looked at isotopic variation from leaf-to-leaf and from plant-to-plant, there has been little attention on potential variations in single leaves. This is particularly important since cuticle is abundant in terrestrial sequences and survives the process of fossilization and diagenesis. In this study, we have investigated the δ13C variation within modern Gingko, Equisetum, Maple, Pine and Spruce. Within all the plant specimens so far analyzed we have found significant δ13C variation (up to 3‰) and a trend from more negative (12C-enriched) values at the leaf margin to more positive (13C-enriched) values at the stem (petiole). We conducted a similar analytical approach to complete fossil leaves from the mid-Cretaceous Dakota Formation, Nebraska. Similar δ13C variation and a trend towards more positive values at the stem were also found in the fossil specimens regardless of size and genus. Therefore, we suggest that an original carbon isotopic pattern within the leaf is preserved during the process of fossilization. The dominant compositional sources for carbon-isotope variability in modern plant matter are cellulose, lignin and epicuticular waxes, with the latter dominating leaf cuticle. Epicuticular waxes are 12C-enriched compared to bulk plant material, lignin and cellulose. We propose that the compositional change between higher wax abundance in leaf material and lignin in stem/wood material is the dominant factor behind the δ13C variation in modern and fossil leaves. The intra-leaf variation found in this study suggests using caution in the interpretation of δ13C in leaf cuticle fragments and bulk terrestrial organic matter for paleo-environmental and -climatic investigations.
Elizabeth Kowalski and Jonathan Bloch
Florida Museum of Natural History, University of Florida, Gainesville, FL 32611-7800
During the Paleocene, mammals diversified and became the dominant land animals. The most substantial mammalian turnover event during this transition was over the Torrejonian-Tiffanian Boundary (Early to Early-Late Paleocene). The Crazy Mountains Basin of south-central Montana preserves one of the best-known superposed sequences of fossil mammal localities spanning the Torrejonian-Tiffanian Boundary, and as such has the potential to clarify the mechanism behind this change. Furthermore, fossil plant localities spanning this transition are abundant in the Crazy Mountains Basin as well. Previous studies have not evaluated the environmental significance of these fossil plant floras in detail. Consideration of fossil plants in this way may eventually help to determine whether climate and habitat change played a role in the faunal transition preserved in the Crazy Mountains Basin.
Well-preserved fossil plants have been recovered from 10 localities spanning the Torrejonian-Tiffanian Boundary. The fossils are primarily whole and fragmentary leaf macrofossils, and fruits, seeds and cone scales also have been collected. Ferns and conifers are abundant in several localities, but the majority of fossils found at the remaining sites are angiosperms. Preliminary investigations show that the angiosperm fossils represent several families and include the genera Leepierceia, Platanus and Davidia. Diversity is low, though comparable with most other mid-continent Paleocene sites, with less than 15 total morphotypes represented.
Harufumi Nishida1, Kazuhiko Uemura2, Masaaki Okuda3, Kazuo Terada4, Takeshi Asakawa5, Atsushi Yabe4, Toshihiro Yamada2 and Luis Felipe Hinojosa6
1Chuo University, Bunkyo, Tokyo, 112-8551, Japan
2National Science Museum, Tokyo, 169-0073, Japan
3Natural History Museum and Institute, Chiba, 260-8682, Chiba, Japan
4Fukui Prefectural Dinosaur Museum, Fukui, 911-8601, Japan
5Chiba University, Chiba, 262-8522, Japan
6Universidad de Chile, Santiago, Chile
We describe a new plant fossil site in southern Patagonia, South America, on the southern shoreline of Riesco Island, northwest of Punta Arenas, in the Magallanes (XII) Region of Chile. The fossils of fragments of plant organs and tissues in various sizes and degrees of preservation are found in calcium-carbonate nodules. The nodules are marine in origin, containing mollusks that may help age determination and biostratigraphic correlation of their source beds. At Riesco Island, thick Upper Cretaceous to Tertiary sediments with a NW-SE trend dipping northeast are well exposed. The nodules are probably derived from sediments in the Palaeocene Chorrillo Chico Formation exposed along the river Rio Boer running south into the Otway Sound (Seno Otway).
Only a limited number of nodules were collected during field research to Riesco Island in 2003, which was originally designed to obtain bog boring samples for palynological study. The nodules are well-sorted, spherical, and are either a single piece of wood or a rock containing a lot of plant debris in a fine sandy matrix. Plant fragments are sometimes packed in round muddy spheres of less than 1-cm diameter scattered in a sandy matrix.
Nodules were studied using the cellulose-acetate peel technique (Joy et al. 1956). Woods are generally damaged by teredo boring, but tissue preservation is not bad. So far, two conifers (Araucarioxylon, Phyllocladoxylon ?), and two angiosperm woods (Lauraceae ? and Nothofagaceae ?) have been identified. Small fragments in the nodules are very interesting. Two small nodules less than 10-cm in diameter have revealed fragments representing a wide range of taxa, including bryophyte shoots, protostelic fern rhizomes, fern rachis and frond segments, conifer and angiosperm leaves, etc. Two different fern sporangia each containing well-preserved tetrahedral spores were also found. One spore type shows echinate ornamentation, while the other has rather smooth surface and the prominent thick equatorial marginal rim characteristic of spores of Lophosoria in the Cyatheaceae. Although very preliminary, this new fossil flora is similar to the Valdivian-type rainforest now distributed in warmer northern areas of Chile.
This study was supported by Grant-in-Aid for Scientific Research No. 14255007 from the Ministry of Education, Culture, Sports, Science and Technology, Japan to H.N.
Surangi W. Punyasena
University of Chicago/Committee on Evolutionary Biology, Chicago, IL, 60637, USA
Paleobotanical data have been used in many forms to reconstruct past climates, from the identification of functional types, to biome-level characterizations, to the quantification of morphological characteristics. But for the palynological record, the most important variable remains the taxonomic makeup of an assemblage.
One of the presumed limitations of using taxonomy to reconstruct climate has been the assumption that the diagnostic relationship between plant and climate is at the species level. Sister species are often found in very different habitats. This is particularly true in the tropics.
Results of a nearly continent-scale analysis of tropical South American vegetation, however, suggest otherwise (Punyasena et al, submitted). We demonstrate that local differences in the richness and abundance of individual plant families can be attributed to climate by identifying covariation between the number of species and individuals within plant families and eight temperature and precipitation measures using the eigenanalysis method of two-field joint single-value decomposition ("joint SVD"). Data were taken from published forest transects and climatology.
Even at the taxonomic resolution of the plant family, several large and ecologically important taxa, including Fabaceae, Bignoniaceae, and Arecaceae, display clear covariation with changes in temperature and precipitation. Most notably, the diversity of many lowland Neotropical families may be more a factor of spatial differences in temperature than precipitation.
Using these climatically sensitive families, I test the feasibility of a probability density function ("pdf")-based reconstruction of temperature and precipitation using family-level data. The resolution and utility of the approach with Quaternary and Cenozoic palynological data will be discussed, including the need to test whether the climate space of tropical plant families remains constant through geologic time.
Department of Geology and Paleontology, National Science Museum, 3-23-1, Hyakunin-cho, Shinjuku-ku, Tokyo, 169-0073 Japan
Two distinct types of megafossil floras are recognized in the lower Miocene rocks of the circum-Japan Sea areas: the Aniai-type of early Early Miocene and the Daijima-type of late Early Miocene. They are stratigraphically distinct and show a marked contrast in their floral and vegetational characteristics, though preserved mostly in terrestrial sediments prevailing volcaniclastic rocks, which show a complicated geology resulting in tectonic deformation and lateral change in lithology. The older or the Aniai-type floras are composed mainly of diverse broad-leaved deciduous trees, intermixed with deciduous and evergreen conifers. The younger or the Daijima-type floras are composed by mixed broad-leaved deciduous and broad-leaved evergreen trees, accompanying conifers. Latitudinal difference in the floral composition is more visible in the Daijima-type, typically represented by the amount of broad-leaved evergreen trees. The sediments with the Daijima-type floras are conformably overlain by marine beds with warm and shallow water faunas of the earliest Middle Miocene. Several radiometric and biostratigraphic evidence indicate that the Aniai-type floras were replaced by the Daijima-type floras at ca. 20 Ma.
Leaf physiognomic analyses of these two types of floras indicate that 1) the areas received moderate and ample rainfalls throughout the Early Miocene, 2) microthermal or cool temperate climate was prevailed in the early Early Miocene, 3) warmer climate (5 degrees Celsius or more increased in mean annual temperature from the age of the Aniai-type) was expanded in the late Early Miocene. The warm period indicated by the Daijima-type floras is a preceding episode of the well-known "mid-Miocene warming" at ca. 16Ma. A pronounced cooler climate indicated by the Aniai-type floras is marked in the circum-Japan Sea areas (Sakhalin, Hokkaido, Honshu and the Korean Peninsula), but such climatic episode has not been well documented in other areas in the world. The episode is due in part to the local paleogeographic shift in relation to the opening of the Japan Sea during 20-15Ma. This tectonic event may related to that of the collision of Indian Subcontinent to Eurasian Continent and the uplift of the Himalayas and Tibetan Plateau, northward migration of Australian Continent, and rotation of Indonesian islands and closure of Indonesian Seaway. These phenomena probably resulted in the change in atmospheric and oceanographic circulations. The marked contrast in the floral composition of the Aniai- and Daijima-type floras provide a feature of the initial phase of the "mid-Miocene warming" in the Early and Middle Miocene boundary.