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Bernard Gomez - One of the best experts on this subject based on the ideXlab platform.
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Diversified Fossil Plant assemblages from the Maastrichtian in Isona (southeastern Pyrenees)
Review of Palaeobotany and Palynology, 2014Co-Authors: Josep Marmi, Bernard Gomez, Caries Martin-closas, Sheila Villalba-breva, Veronique Daviero-gomezAbstract:At the end of the 1970s, several lower Maastrichtian localities with Plant megaFossil remains were reported near the village of Isona in the Tremp Syncline of the southeastern Pyrenees. These assemblages include conifers (taxodioids and cheirolepidiaceans), monocot angiosperms (Sabalites palms and likely Pandanaceans) and at least 15 types of magnoliid and eudicot angiosperm leaves. Conifers, Sabalites palms and some eudicots are shared with coeval localities in Portugal, France, Austria and Romania. In addition, Sabalites palms and at least five types of magnoliids and eudicots found here are very similar to Fossil leaves reported from Upper Cretaceous localities in North America, suggesting that the Isona flora possibly share some elements with North American floras. Data from the Isona locality also indicate that eudicots dominated the floodplain Plant associations in fully continental-influenced terrestrial environments. (C) 2014 Elsevier B.V. All rights reserved.
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Plant inclusions from the Cenomanian flints of Archingeay, Les Nouillers, western France
Lethaia, 2014Co-Authors: Jean-david Moreau, Bernard Gomez, Didier Neraudeau, Paul Tafforeau, Eric DépréAbstract:Here, we report flint nodules bearing Fossil Plant inclusions from the early Cenoma- nian of the Font-de-Benon sand quarry, between the villages of Archingeay and Les Nouillers, Charente-Maritime, western France. The broken-open surfaces of these dense siliceous rocks only partly show the whole diversity, which is established using a non-destructive, multi-scale approach based on propagation phase-contrast X-ray synchrotron microtomography. The conifer genera Brachyphyllum, Frenelopsis, Gein- itzia, and Glenrosa have three-dimensional preservation, and vegetative and reproduc- tive organs are in connection in some cases. The flint nodules formed by silicification of Cenomanian sediments, probably as a result of an intensive period of soil alteration and leaching under warm and wet climate during the Eocene. Although the time was long between the Cenomanian sedimentation and the Eocene silicification, the Fossil Plants show three-dimensional external morphology. These mineralizations are inter- preted as fine silica microcrystallization over the cell walls and thus are examples of late silica permineralization. The association of foraminifers, echinoids, sponge spicules, and conifers suggests that the Cenomanian sediments were deposited in a coastal and open to the sea palaeoenvironment, near a conifer-dominated mangrove.
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The rise to dominance of the angiosperm kingdom: dispersal, habitat widening and evolution during the Late Cretaceous of Europe
Lethaia, 2010Co-Authors: Clément Coiffard, Bernard GomezAbstract:he earliest Fossil records of angiosperms in Europe occur in the Barremian and consist of freshwater wetland Plants. From the Barremian onwards, angiosperms show a stepwise widening of their ecological range with the result that they inhabited most environments by the Cenomanian. Nevertheless, most angiosperms had still restricted habitats, while a few angiosperm trees were confined to disturbed environments, such as channel margins. A Wagner's Parsimony Method analysis performed on a Fossil Plant and locality database from the Turonian to the Campanian of Europe indicates continued decrease in richness of ferns and gymnosperms compared with angiosperms, turnover between conifer and palm trees in freshwater-related swamps at about the Cenomanian/Turonian boundary, and spreading of angiosperm trees through the floodplains. The ecological range of angiosperm trees was increased, being recorded in channel margins from the Cenomanian and spreading over floodplains (e.g. Platanaceae) and swamps (e.g. Arecaceae) by the Campanian. These new ecological ranges and successions went with innovative architectures, such as dicot trees and palm trees. Most living core angiosperm families had their earliest representatives in the Late Cretaceous, which should be considered as the dawn of modern angiosperm forests. square Core angiosperms, Europe, Late Cretaceous, palms, Wagner's Parsimony Method.
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Orientated Plant fragments revealing tidal palaeocurrents in the Fumanya mudflat (Maastrichtian, southern Pyrenees): Insights in palaeogeographic reconstructions
Palaeogeography Palaeoclimatology Palaeoecology, 2010Co-Authors: Violeta Riera, Josep Marmi, Oriol Oms, Bernard GomezAbstract:Leafy axis fragments of Frenelopsis sp., leaves of Sabalites longirhachis (Unger) Kvacek et Herman and logs are common in the Maastrichtian of the basal Tremp Formation in the Vallcebre Syncline (southern Pyrenees). The largest Plant remains, i.e. leaves of S. longirhachis and logs, appear scattered and randomly orientated, whereas the smallest Plant remains, i.e. Frenelopsis sp., are aligned in a clear east-west trend. This orientation (based on 117 measurements) is consistent with the basin palaeogeography, which was an E-W elongated foreland trough that confined tidal palaeoflow and deposits such as tidal bores. In the absence of usual sedimentary indicators, e.g. tractive structures and base marks, the accurate study of Fossil Plant orientations can largely assist palaeoflow determinations in palaeogeographic reconstruction
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Application of the Wagner's Parcimony Method in Fossil Plant assemblages from the Cretaceous of Europe
Review of Palaeobotany and Palynology, 2008Co-Authors: C. Coiffard, Bernard Gomez, André Nel, J. Kvacek, Didier Neraudeau, Frédéric ThévenardAbstract:Wagner's Parsimony Method, a grouping method used in phylogeny and synecology, is applied for the first time to taxon lists of Fossil Plant assemblages from the AlbianCenomanian of Europe. When compared to a "classical" Correspondence Analysis, WPM allows for a higher resolution, using taxa named in "cf." or "aff." and points out both clusters and gradients. WPM results in a tree in which localities order according to their species content and minimizes the number of changes of character states (presence/absence), whereas Correspondence Analysis plots the localities along axes and maximizes the inertia ("variance" explaining most differences between localities). Close relationships exist between the Plant palaeobiocenoses and palaeobiotopes, the latter being inferred from taphonomical data (especially the salinity and the clastic size). The space/time working scale can be very fine, up to the landscape ecology level.
Brian J Enquist - One of the best experts on this subject based on the ideXlab platform.
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cope s rule and the evolution of long distance transport in vascular Plants allometric scaling biomass partitioning and optimization
Plant Cell and Environment, 2003Co-Authors: Brian J EnquistAbstract:Recent advances in allometric theory have proposed a novel quantitative framework by which to view the evolution of Plant form and function. This general theory has placed strong emphasis on the importance of long-distance transport in shaping the evolution of many attributes of Plant form and function. Specifically, it is hypothesized that with the evolutionary increase in Plant size natural selection has also resulted in vascular networks that minimize scaling of total hydrodynamic resistance associated with increasing transport distances. Herein the central features of this theory are reviewed and a broad sampling of supporting but yet preliminary empirical data are analysed. In particular, subtle attributes of the scaling of tracheid and vessel anatomy are hypothesized to be crucial for the evolution of increased Plant size. Furthermore, the importance of minimizing hydrodynamic resistance associated with increased transport distances is also hypothesized to be reflected in an isometric scaling relationship between stem mass, M S and root mass, M R ( i.e. M S µ µ µ M R ). Preliminary data from multiple extant and Fossil Plant taxa provide tantalizing evidence supporting the predicted relationships. Together, these results suggest that selection for the minimization of the scaling of hydrodynamic resistance within Plant vascular networks has in turn allowed for the enormous diversification in vascular Plant size.
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general patterns of taxonomic and biomass partitioning in extant and Fossil Plant communities
Nature, 2002Co-Authors: Brian J Enquist, John P Haskell, Bruce H TiffneyAbstract:A central goal of evolutionary ecology is to identify the general features maintaining the diversity of species assemblages. Understanding the taxonomic and ecological characteristics of ecological communities provides a means to develop and test theories about the processes that regulate species coexistence and diversity. Here, using data from woody Plant communities from different biogeographic regions, continents and geologic time periods, we show that the number of higher taxa is a general power-function of species richness that is significantly different from randomized assemblages. In general, we find that local communities are characterized by fewer higher taxa than would be expected by chance. The degree of taxonomic diversity is influenced by modes of dispersal and potential biotic interactions. Further, changes in local diversity are accompanied by regular changes in the partitioning of community biomass between taxa that are also described by a power function. Our results indicate that local and regional processes have consistently regulated community diversity and biomass partitioning for millions of years.
Lutz Kunzmann - One of the best experts on this subject based on the ideXlab platform.
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Fossil Plant stomata indicate decreasing atmospheric co 2 prior to the eocene oligocene boundary
Climate of The Past, 2015Co-Authors: Margret Steinthorsdottir, Lutz Kunzmann, Amanda S Porter, Aidan Holohan, Margaret E Collinson, Jennifer C McelwainAbstract:Abstract. A unique stratigraphic sequence of Fossil leaves of Eotrigonobalanus furcinervis (extinct trees of the beech family, Fagaceae) from central Germany has been used to derive an atmospheric pCO2 record with multiple data points spanning the late middle to late Eocene, two sampling levels which may be earliest Oligocene, and two samples from later in the Oligocene. Using the inverse relationship between the density of stomata and pCO2, we show that pCO2 decreased continuously from the late middle to late Eocene, reaching a relatively stable low value before the end of the Eocene. Based on the subsequent records, pCO2 in parts of the Oligocene was similar to latest Eocene values. These results suggest that a decrease in pCO2 preceded the large shift in marine oxygen isotope records that characterizes the Eocene–Oligocene transition and that when a certain threshold of pCO2 change was crossed, the cumulative effects of this and other factors resulted in rapid temperature decline, ice build up on Antarctica and hence a change of climate mode.
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Early Oligocene Plant taphocoenoses of the Haselbach megafloral complex and the reconstruction of palaeovegetation
Palaeobiodiversity and Palaeoenvironments, 2012Co-Authors: Lutz Kunzmann, Harald WaltherAbstract:In this article, vegetational reconstructions of leaf floras from the early Oligocene Haselbach megafloral complex, which have been published by several authors since the 1960s, are compiled, summarised, reconsidered and partly revised. The geological setting of the Fossil material is updated based on the most recent monographs on stratigraphy and geology of the mid-German Paleogene. An annotated list of the leaf component of the Haselbach complex floras is given using the most recent nomenclature and taxonomy. Reconstructions previously illustrated as vegetational schemes are redrawn, with slight modifications to the original versions. Original captions of the schemes are revised with special attention given to the Fossil Plant names and sediment facies types. Typical Fossil specimens that characterise the corresponding Plant taphocoenoses quite well are included to complement the drawings. The importance of phytotaphonomic and palaeoecological data for the reconstructions of palaeoenvironments is emphasised.
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A putative gnetalean gymnosperm Cariria orbiculiconiformis gen. nov. et spec. nov. from the Early Cretaceous of northern Gondwana
Review of Palaeobotany and Palynology, 2011Co-Authors: Lutz Kunzmann, Volker Wilde, Barbara A. R. Mohr, Mary Elizabeth Cerruti Bernardes-de-oliveiraAbstract:Cariria orbiculiconiformis gen. nov. et spec. nov., a gymnosperm with gnetoid characters is described from the upper Aptian Crato Formation of the Araripe Basin in northeastern Brazil. Gross-morphology and anatomical details have been studied and characters have been discussed in respect to various seed Plants. Several of these characters fit best with those of Gnetales and their putative Fossil allies. However, the Fossil Plant cannot be assigned to any known extinct or extant group of seed Plants in their current circumscription. Stem gross-morphology, xylotomical characters and epidermal features indicate a gnetophytic relationship, whereas characters of the reproductive organs are rather distinct from those found in extant taxa. The reproductive unit of the new taxon represents a triple organ consisting of two dichasial ovulate structures and one median pollen-producing structure containing smooth, monosulcate, boat-shaped pollen in-situ. Each ovulate structure consists of two distinct pairs of bracts, a sterile one at the base and a fertile one forming a terminal orbicular capsule. Stiff processes found in the apex of the ovulate structure may represent micropylar tubes of seeds, as seen in the Bennettitales–Erdtmanithecales–Gnetales group. C. orbiculiconiformis gen. nov. et spec. nov. was ans herbaceous or semi-shrub-like Plant that may have been adapted to the r-strategy in a stressful environment.
Margret Steinthorsdottir - One of the best experts on this subject based on the ideXlab platform.
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moderate levels of eocene pco2 indicated by southern hemisphere Fossil Plant stomata
Geology, 2019Co-Authors: Margret Steinthorsdottir, Vivi Vajda, Mike Pole, G R HoldgateAbstract:Reducing the uncertainty in predictions of future climate change is one of today’s greatest scientific challenges, with many significant problems unsolved, including the relationship between pCO2 a ...
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Fossil Plant stomata indicate decreasing atmospheric co 2 prior to the eocene oligocene boundary
Climate of The Past, 2015Co-Authors: Margret Steinthorsdottir, Lutz Kunzmann, Amanda S Porter, Aidan Holohan, Margaret E Collinson, Jennifer C McelwainAbstract:Abstract. A unique stratigraphic sequence of Fossil leaves of Eotrigonobalanus furcinervis (extinct trees of the beech family, Fagaceae) from central Germany has been used to derive an atmospheric pCO2 record with multiple data points spanning the late middle to late Eocene, two sampling levels which may be earliest Oligocene, and two samples from later in the Oligocene. Using the inverse relationship between the density of stomata and pCO2, we show that pCO2 decreased continuously from the late middle to late Eocene, reaching a relatively stable low value before the end of the Eocene. Based on the subsequent records, pCO2 in parts of the Oligocene was similar to latest Eocene values. These results suggest that a decrease in pCO2 preceded the large shift in marine oxygen isotope records that characterizes the Eocene–Oligocene transition and that when a certain threshold of pCO2 change was crossed, the cumulative effects of this and other factors resulted in rapid temperature decline, ice build up on Antarctica and hence a change of climate mode.
Jennifer C Mcelwain - One of the best experts on this subject based on the ideXlab platform.
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Fossil Plant stomata indicate decreasing atmospheric co 2 prior to the eocene oligocene boundary
Climate of The Past, 2015Co-Authors: Margret Steinthorsdottir, Lutz Kunzmann, Amanda S Porter, Aidan Holohan, Margaret E Collinson, Jennifer C McelwainAbstract:Abstract. A unique stratigraphic sequence of Fossil leaves of Eotrigonobalanus furcinervis (extinct trees of the beech family, Fagaceae) from central Germany has been used to derive an atmospheric pCO2 record with multiple data points spanning the late middle to late Eocene, two sampling levels which may be earliest Oligocene, and two samples from later in the Oligocene. Using the inverse relationship between the density of stomata and pCO2, we show that pCO2 decreased continuously from the late middle to late Eocene, reaching a relatively stable low value before the end of the Eocene. Based on the subsequent records, pCO2 in parts of the Oligocene was similar to latest Eocene values. These results suggest that a decrease in pCO2 preceded the large shift in marine oxygen isotope records that characterizes the Eocene–Oligocene transition and that when a certain threshold of pCO2 change was crossed, the cumulative effects of this and other factors resulted in rapid temperature decline, ice build up on Antarctica and hence a change of climate mode.
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Fossil Plant relative abundances indicate sudden loss of late triassic biodiversity in east greenland
Science, 2009Co-Authors: Jennifer C Mcelwain, Peter J Wagner, Stephen P HesselboAbstract:The pace of Late Triassic (LT) biodiversity loss is uncertain, yet it could help to decipher causal mechanisms of mass extinction. We investigated relative abundance distributions (RADs) of six LT Plant assemblages from the Kap Stewart Group, East Greenland, to determine the pace of collapse of LT primary productivity. RADs displayed not simply decreases in the number of taxa, but decreases in the number of common taxa. Likelihood tests rejected a hypothesis of continuously declining diversity. Instead, the RAD shift occurred over the upper two-to-four Fossil Plant assemblages and most likely over the last three (final 13 meters), coinciding with increased atmospheric carbon dioxide concentration and global warming. Thus, although the LT event did not induce mass extinction of Plant families, it accompanied major and abrupt change in their ecology and diversity.