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Derek E G Briggs - One of the best experts on this subject based on the ideXlab platform.

  • the Fossilization of eurypterids a result of molecular transformation
    PALAIOS, 2007
    Co-Authors: Neal S Gupta, Derek E G Briggs, Erik O Tetlie, Richard D Pancost
    Abstract:

    The fossil remains of eurypterid cuticles in this study yield long-chain (thermal maturity as demonstrated by Raman spectroscopy. Analysis (including thermochemolysis) of the cuticle of modern scorpions and horseshoe crabs, living relatives of the eurypterids, shows that C16 and C18 fatty acyl moieties likewise dominate. If we assume that the original composition of the eurypterid cuticle is similar to that of living chelicerates, Fossilization likely involves the incorporation of such lipids into an aliphatic polymer. Such a process of in situ polymerization accounts for the fossil record of eurypterids.

  • understanding Fossilization experimental pyritization of plants
    Geology, 2001
    Co-Authors: Stephen T Grimes, Fiona Brock, David Rickard, Kevin L Davies, Dianne Edwards, Derek E G Briggs, John R Parkes
    Abstract:

    The process of Fossilization is poorly understood. However, it is central to our understanding of the evolution of life. It is unclear how plant tissues become fossilized, whether Fossilization is selective to specific biopolymers, or whether original organic constituents survive. We have replicated the Fossilization process in the laboratory by using both microbial and chemical approaches to pyritize plant debris. These results demonstrate that initial pyritization can be an extremely rapid process (within 80 days) and is driven by anaerobic bacterial-mediated decay. Initially, pyrite precipitates on and within plant cell walls and in the spaces between them. Further decay and infilling at all scales preserves broad cellular anatomy. The results have implications for Fossilization in general and the fidelity of the taxonomic and biomolecular information preserved in fossils.

  • the biomolecular paleontology of continental fossils
    Paleobiology, 2000
    Co-Authors: Derek E G Briggs, Richard P Evershed, Matthew J Lockheart
    Abstract:

    Abstract The preservation of compounds of biological origin (nucleic acids, proteins, carbohydrates, lipids, and resistant biopolymers) in terrigenous fossils and the chemical and structural changes that they undergo during Fossilization are discussed over three critical stratigraphic levels or “time slices.” The youngest of these is the archeological record (e.g., <10 k.y. b.p.), when organic matter from living organisms undergoes the preliminary stages of Fossilization (certain classes of biomolecule are selectively preserved while others undergo rapid degradation). The second time slice is the Tertiary. Well-preserved fossils of this age retain diagenetically modified biomarkers and biopolymers for which a product–precursor relationship with the original biological materials can still be identified. The final time slice is the Carboniferous. Organic material of this age has generally undergone such extensive diagenetic degradation that only the most resistant biopolymers remain and these have undergone...

  • Fossilization of feathers
    Geology, 1995
    Co-Authors: Paul G. Davis, Derek E G Briggs
    Abstract:

    Scanning electron microscopy of feathers has revealed evidence that a bacterial glycocalyx (a network of exocellular polysaccharide fibers) played a role in promoting their Fossilization in some cases. This mode of preservation has not been reported in other soft tissues. The majority of fossil feathers are preserved as carbonized traces. More rarely, bacteria on the surface are replicated by authigenic minerals (bacterial autolithification). The feathers of Archaeopteryx are preserved mainly by imprintation following early lithification of the substrate and decay of the feather. Lacustrine settings provide the most important taphonomic window for feather preservation. Preservation in terrestrial and normal-marine settings involves very different processes (in amber and in authigenically mineralized coprolites, respectively). Therefore, there may be a significant bias in the avian fossil record in favor of inland water habitats.

  • Fossilization of soft tissue in the laboratory
    Science, 1993
    Co-Authors: Derek E G Briggs, Amanda J Kear
    Abstract:

    Some of the most remarkable fossils preserve cellular details of soft tissues. In many of these, the tissues have been replaced by calcium phosphate. This process has been assumed to require elevated concentrations of phosphate in sediment pore waters. In decay experiments modern shrimps became partially mineralized in amorphous calcium phosphate, preserving cellular details of muscle tissue, particularly in a system closed to oxygen. The source for the formation of calcium phosphate was the shrimp itself. Mineralization, which was accompanied by a drop in pH, commenced within 2 weeks and increased in extent for at least 4 to 8 weeks. This mechanism halts the normal loss of detail of soft-tissue morphology before Fossilization. Similar closed conditions would prevail where organisms are rapidly overgrown by microbial mats.

François Orange - One of the best experts on this subject based on the ideXlab platform.

  • experimental Fossilization of the thermophilic gram positive bacterium geobacillus sp7a a long duration preservation study
    Geomicrobiology Journal, 2014
    Co-Authors: François Orange, Francès Westall, Jean-robert Disnar, Samuel Dupont, Olivier Le Goff, Nadege Bienvenu, M. Le Romancer
    Abstract:

    Recent experiments to fossilize microorganisms using silica have shown that the Fossilization process is far more complex than originally thought; microorganisms not only play an active role in silica precipitation but may also remain alive while silica is precipitating on their cell wall. To better understand the mechanisms that lead to the preservation of fossilized microbes in recent and ancient rocks, we experimentally silicified a Gram-positive bacterium, Geobacillus SP7A, over a period of five years. The microbial response to experimental Fossilization was monitored with the use of LIVE/DEAD staining to assess the structural integrity of the cells during Fossilization. It documented the crucial role of silicification on the preservation of the cells and of their structural integrity after several years. Electron microscopy observations showed that initial Fossilization of Gram-positive bacteria was extremely rapid, thus allowing very good preservation of Geobacillus SP7A cells. A thick layer of sili...

  • Preservation and Evolution of Organic Matter During Experimental Fossilisation of the Hyperthermophilic Archaea Methanocaldococcus jannaschii
    Origins of life and evolution of the biosphere : the journal of the International Society for the Study of the Origin of Life, 2012
    Co-Authors: François Orange, Francès Westall, Jean-robert Disnar, Nadege Bienvenu, Pascale Gautret, Nathalie Lottier, Daniel Prieur
    Abstract:

    Identification of the earliest traces of life is made difficult by the scarcity of the preserved microbial remains and by the alteration and potential contamination of the organic matter (OM) content of rocks. These factors can confuse interpretations of the biogenicity and syngenicity of fossilised structures and organic molecules found in ancient rocks. In order to improve our knowledge of the fossilisation processes and their effects at the molecular level, we made a preliminary study of the fate of OM during experimental fossilisation. Changes in the composition and quantity of amino acids, monosaccharides and fatty acids were followed with HPLC, GC and GC-MS analyses during 1 year of silicification of the hyperthermophilic Archaea Methanocaldococcus jannaschii. Although the cells themselves did not fossilise and the accompanying extracellular polymeric substances (EPS) did, our analyses showed that the OM initially present in both cells and EPS was uniformly preserved in the precipitated silica, with amino acids and fatty acids being the best preserved compounds. This study thus completes previous data obtained by electron microscopy investigations of simulated microbial fossilisation and can help better identification and interpretation of microbial biosignatures in both ancient rocks and in recent hydrothermal formations and sediments.

  • Metal cation binding by the hyperthermophilic microorganism, Archaea Methanocaldococcus Jannaschii, and its effects on silicification
    Palaeontology, 2011
    Co-Authors: François Orange, Daniel Prieur, Francès Westall, Jean-robert Disnar, Patrick Baillif
    Abstract:

    A series of experiments was conducted to determine the capacity of an archaeal strain, Methanocaldococcus jannaschii, to bind metals and to study the effects of metal binding on the subsequent silicification of the microorganisms. The results showed that M. jannaschii can rapidly bind several metal cations (Fe3+, Ca2+, Pb2+, Zn2+, Cu2+). Considering the lack of silicification of this strain without metal binding, these experiments demonstrate that Fe(III) ion binding to the cell wall components was of fundamental importance for successful silicification and, especially, for the excellent preservation of the cell wall. This study brings new elements to the understanding of Fossilization processes, showing that the positive effect of Fe(III) on silicification, already known for Bacteria, can also apply to Archaea and that this preliminary binding can be decisive for the subsequent Fossilization of these organisms. Knowledge of these mechanisms can be helpful for the search and the identification of microfossils in both terrestrial and extraterrestrials rocks, and in particular on Mars.

  • Experimental silicification of the extremophilic Archaea Pyrococcus abyssi and Methanocaldococcus jannaschii: applications in the search for evidence of life in early Earth and extraterrestrial rocks
    Geobiology, 2009
    Co-Authors: François Orange, Daniel Prieur, M. Le Romancer, Francès Westall, Jean-robert Disnar, N. Bienvenu, Christian Défarge
    Abstract:

    Hydrothermal activity was common on the early Earth and associated micro-organisms would most likely have included thermophilic to hyperthermophilic species. 3.5–3.3 billion-year-old, hydrothermally influenced rocks contain silicified microbial mats and colonies that must have been bathed in warm to hot hydrothermal emanations. Could they represent thermophilic or hyperthermophilic micro-organisms and if so, how were they preserved? We present the results of an experiment to silicify anaerobic, hyperthermophilic micro-organisms from the Archaea Domain Pyrococcus abyssi and Methanocaldococcus jannaschii, that could have lived on the early Earth. The micro-organisms were placed in a silica-saturated medium for periods up to 1 year. Pyrococcus abyssi cells were fossilized but the M. jannaschii cells lysed naturally after the exponential growth phase, apart from a few cells and cell remains, and were not silicified although their extracellular polymeric substances were. In this first simulated Fossilization of archaeal strains, our results suggest that differences between species have a strong influence on the potential for different micro-organisms to be preserved by Fossilization and that those found in the fossil record represent probably only a part of the original diversity. Our results have important consequences for biosignatures in hydrothermal or hydrothermally influenced deposits on Earth, as well as on early Mars, as environmental conditions were similar on the young terrestrial planets and traces of early Martian life may have been similarly preserved as silicified microfossils.

Nj Tosca - One of the best experts on this subject based on the ideXlab platform.

  • Early formation and taphonomic significance of kaolinite associated with Burgess Shale fossils
    'Geological Society of America', 2020
    Co-Authors: Wade J, Rp Anderson, Briggs Deg, Ee Saupe, Nj Tosca
    Abstract:

    The role of minerals in Burgess Shale–type Fossilization is controversial, particularly that of the clay mineral kaolinite. Kaolinite may have formed on carcasses or attached to them as they decayed, stabilizing organic matter. Alternatively, kaolinite may have formed during metamorphism, playing no role in the preservation of soft tissues. Evaluating the formation and taphonomic role of kaolinite is difficult, because the mineralogy of Burgess Shale–type fossils is incompletely known. We used in situ selected-area X-ray diffraction to constrain the mineralogy of fossils from the classic Burgess Shale Formation in British Columbia, Canada. Fossils can be distinguished from the matrix that surrounds them by the presence of dolomite, kaolinite, and pyrite. Chlorite may be more abundant in the matrix. The preferential survival of kaolinite in association with fossils provides evidence of early diagenetic clay-organic interactions that protected the clay from metamorphic transformation. Kaolinite likely played a crucial role in Fossilization, inhibiting the growth of heterotrophic bacteria and aiding polymerization of soft tissue biomolecules. This may result in biases in soft-tissue preservation to areas and times where kaolinite was prevalent

  • Aluminosilicate haloes preserve complex life approximately 800 million years ago
    'The Royal Society', 2020
    Co-Authors: Rp Anderson, Nj Tosca, Briggs Deg, Kd Bergmann, Gm Hughes, Ah Knoll, Cinque G, Akey A
    Abstract:

    Mudstone-hosted microfossils are a major component of the Proterozoic fossil record, particularly dominating the record of early eukaryotic life. Early organisms possessed no biomineralized parts to resist decay and controls on their Fossilization in mudstones are poorly understood. Consequently, the Proterozoic fossil record is compromised—we do not know whether changing temporal/spatial patterns of microfossil occurrences reflect evolution or the distribution of favourable Fossilization conditions. We investigated Fossilization within the approximately 1000 Ma Lakhanda Group (Russia) and the approximately 800 Ma Svanbergfjellet and Wynniatt formations (Svalbard and Arctic Canada). Vertical sections of microfossils and surrounding matrices were extracted from thin sections by focused ion beam milling. Elemental mapping and synchrotron-based infrared microspectroscopy revealed that microfossils are surrounded by haloes rich in aluminium, probably hosted in kaolinite. Kaolinite has been implicated in Cambrian Burgess Shale-type (BST) Fossilization and is known to slow the growth of degraders. The Neoproterozoic mudstone microfossil record may be biased to tropical settings conducive to kaolinite formation. These deposits lack metazoan fossils even though they share Fossilization conditions with younger BST deposits that are capable of preserving non-mineralizing metazoans. Thus metazoans, at least those typically preserved in BST deposits, were probably absent from sedimentary environments before approximately 800 Ma

  • A mineralogical signature for Burgess Shale–type Fossilization
    'Geological Society of America', 2018
    Co-Authors: Rp Anderson, Nj Tosca, Rr Gaines, Mongiardino Koch N, Briggs Deg
    Abstract:

    Burgess Shale-type (BST) Fossilization of carbonaceous remains that are ordinarily lost to decay is critical to our understanding of the early evolution of complex life. Sediment composition, particularly the abundance of certain clay minerals, has been invoked as a significant factor in BST Fossilization. X-ray diffraction data for 213 Cambrian shales from 19 sedimentary successions on four continents provide the first comprehensive test of the association of clay mineral assemblages with BST fossils. Samples containing BST fossils yield mineralogical compositions that form a subset within the range represented by samples containing only fossil mineralized skeletons. Logistic regression and classification tree methods reveal that BST fossils are more likely to be found in sediments rich in berthierine/chamosite and poor in celadonite and illite. This characteristic clay mineralogy probably reflects a high kaolinite/smectite ratio in the original sediment and enhanced iron availability during early diagenesis. Models derived from both methods can predict the occurrence of BST fossils in fossiliferous samples based on clay mineralogy with ~80% accuracy, providing a mineralogical signature that may be useful in refining the search for BST fossils on Earth and beyond

Orange François - One of the best experts on this subject based on the ideXlab platform.

  • Fossilisation expérimentale de bactéries : appui à l?identification de signatures microbiologiques terrestres et extraterrestres
    HAL CCSD, 2008
    Co-Authors: Orange François
    Abstract:

    Since the earliest life forms known to date (> 3 Gyr) were preserved due to the precipitation of dissolved silica on cellular structures (silicification), we undertook an experiment to silicify several microbial species (the Archaea Methanocaldococcus jannaschii and Pyrococcus abyssi, and the Bacteria Chloroflexus aurantiacus and Geobacillus sp.), representative of anaerobic, thermophilic microorganisms that could have existed in the environmental conditions of early Earth and early Mars. This is the first time that Archaea have been used in a simulated fossilisation experiment and one of the very first fossilisations of thermophilic microorganisms.The experimental fossilisation was monitored by electron microscopy (SEM, TEM, Cryo-SEM) for the morphological study, and by chemical analysis (GC, GC-MS, HPLC) for the study of the preservation or degradation of organic matter during silicification.This experiment demonstrated that not all microorganisms silicify under the same conditions. M. jannaschii cells lysed rapidly, although the EPS (extracellular polymeric substances) were preserved, as opposed to P. abyssi, Geobacillus sp. and C. aurantiacus where the cells were preserved and fossilized with differing degrees of silicification between species. The microorganisms apparently used active mechanisms to protect themselves temporarily from silicification, such as EPS production or silica repulsion. These results suggest that differences between species have a strong influence on the potential for different microorganisms to be preserved by fossilisation.This study provides valuable insight into the silicification and preservation processes of the kind of microorganisms that could have existed on the early Earth. Knowledge of these mechanisms can be helpful for the search and the identification of microfossils in both terrestrial and extraterrestrials rocks, and in the particular case of Mars.Puisque les premières formes de vie connues à ce jour (> 3 Ga) ont été préservées grâce à la précipitation de silice sur les structures cellulaires (silicification), nous avons mené la fossilisation expérimentale de différentes souches microbiennes (les Archées Methanocaldococcus jannaschii et Pyrococcus abyssi, les Bactéries Chloroflexus aurantiacus et Geobacillus sp.), représentatives des micro-organismes thermophiles, anaérobies et autotrophes qui auraient pu exister dans les conditions environnementales de la Terre primitive ou de Mars. Il s'agit de la première fossilisation expérimentale d'Archées, et l'une des toutes premières concernant des micro-organismes thermophiles.La fossilisation expérimentale a été suivie en microscopie électronique (MEB, MET, Cryo-MEB) pour l'étude morphologique, et par des analyses chimiques (GC, GC-MS, HPLC) pour l'étude de la dégradation ou de la préservation de la matière organique durant la fossilisation.Cette étude a montré que tous les micro-organismes ne pouvaient pas être silicifiés. Les cellules de M. jannaschii ont ainsi lysé rapidement tandis, qu'à l'inverse, celles de P. abyssi, Geobacillus sp. et C. aurantiacus ont été préservées, avec des intensités de la fossilisation variables selon les espèces. Les micro-organismes ont souvent mis en place des mécanismes actifs pour se protéger de la silicification, comme la production d'EPS, ou la répulsion de la silice. Ces résultats suggèrent que les différences entre espèces ont une forte influence sur le potentiel des différents micro-organismes à être préservés par la fossilisation.Cette étude fournit un bon aperçu des processus de silicification et de préservation des types de micro-organismes qui auraient pu exister sur la Terre primitive. La connaissance de ces mécanismes peut être utile pour la recherche et l'identification de microfossiles dans les roches terrestres et extraterrestres, tout particulièrement dans le cas de Mars

  • Fossilisation expérimentale de bactéries (appui à l identification de signatures microbiologiques terrestres et extraterrestres)
    2008
    Co-Authors: Orange François, Westall Frances, Disnar Jean-robert
    Abstract:

    Puisque les premières formes de vie connues à ce jour (> 3 Ga) ont été préservées grâce à la précipitation de silice sur les structures cellulaires (silicification), nous avons mené la fossilisation expérimentale de différentes souches microbiennes (les Archées Methanocaldococcus jannaschii et Pyrococcus abyssi ; les Bactéries Chloroflexus aurantiacus et Geobacillus sp.), représentatives des micro-organismes thermophiles, anaérobies et autotrophes qui auraient pu exister dans les conditions environnementales de la Terre primitive ou de Mars. Il s agit de la première fossilisation expérimentale d Archées, et l une des toutes premières concernant des micro-organismes thermophiles. La fossilisation expérimentale a été suivie en microscopie électronique (MEB, MET, Cryo-MEB) pour l étude morphologique, et par des analyses chimiques (GC, GC-MS, HPLC) pour l étude de la dégradation ou de la préservation de la matière organique durant la fossilisation. Cette étude a montré que tous les micro-organismes ne pouvaient pas être silicifiés. Les cellules de M. jannaschii ont ainsi lysé rapidement. A l inverse, celles de P. abyssi, Geobacillus sp. et C. aurantiacus ont été préservées, avec des intensités de la fossilisation variables selon les espèces. Les micro-organismes ont souvent mis en place des mécanismes actifs pour se protéger de la silicification, comme la production d EPS, ou la répulsion de la silice. Ces résultats suggèrent que les différences entre espèces ont une forte influence sur le potentiel des différents micro-organismes à être préservés par la fossilisation. Cette étude fournit un bon aperçu des processus de silicification et de préservation des types de micro-organismes qui auraient pu exister sur la Terre primitive. La connaissance de ces mécanismes peut être utile pour la recherche et l identification de microfossiles dans les roches terrestres et extraterrestres, tout particulièrement dans le cas de Mars.ORLEANS-BU Sciences (452342104) / SudocORLEANS-ISTO (452342307) / SudocSudocFranceF

Briggs Deg - One of the best experts on this subject based on the ideXlab platform.

  • Early formation and taphonomic significance of kaolinite associated with Burgess Shale fossils
    'Geological Society of America', 2020
    Co-Authors: Wade J, Rp Anderson, Briggs Deg, Ee Saupe, Nj Tosca
    Abstract:

    The role of minerals in Burgess Shale–type Fossilization is controversial, particularly that of the clay mineral kaolinite. Kaolinite may have formed on carcasses or attached to them as they decayed, stabilizing organic matter. Alternatively, kaolinite may have formed during metamorphism, playing no role in the preservation of soft tissues. Evaluating the formation and taphonomic role of kaolinite is difficult, because the mineralogy of Burgess Shale–type fossils is incompletely known. We used in situ selected-area X-ray diffraction to constrain the mineralogy of fossils from the classic Burgess Shale Formation in British Columbia, Canada. Fossils can be distinguished from the matrix that surrounds them by the presence of dolomite, kaolinite, and pyrite. Chlorite may be more abundant in the matrix. The preferential survival of kaolinite in association with fossils provides evidence of early diagenetic clay-organic interactions that protected the clay from metamorphic transformation. Kaolinite likely played a crucial role in Fossilization, inhibiting the growth of heterotrophic bacteria and aiding polymerization of soft tissue biomolecules. This may result in biases in soft-tissue preservation to areas and times where kaolinite was prevalent

  • Aluminosilicate haloes preserve complex life approximately 800 million years ago
    'The Royal Society', 2020
    Co-Authors: Rp Anderson, Nj Tosca, Briggs Deg, Kd Bergmann, Gm Hughes, Ah Knoll, Cinque G, Akey A
    Abstract:

    Mudstone-hosted microfossils are a major component of the Proterozoic fossil record, particularly dominating the record of early eukaryotic life. Early organisms possessed no biomineralized parts to resist decay and controls on their Fossilization in mudstones are poorly understood. Consequently, the Proterozoic fossil record is compromised—we do not know whether changing temporal/spatial patterns of microfossil occurrences reflect evolution or the distribution of favourable Fossilization conditions. We investigated Fossilization within the approximately 1000 Ma Lakhanda Group (Russia) and the approximately 800 Ma Svanbergfjellet and Wynniatt formations (Svalbard and Arctic Canada). Vertical sections of microfossils and surrounding matrices were extracted from thin sections by focused ion beam milling. Elemental mapping and synchrotron-based infrared microspectroscopy revealed that microfossils are surrounded by haloes rich in aluminium, probably hosted in kaolinite. Kaolinite has been implicated in Cambrian Burgess Shale-type (BST) Fossilization and is known to slow the growth of degraders. The Neoproterozoic mudstone microfossil record may be biased to tropical settings conducive to kaolinite formation. These deposits lack metazoan fossils even though they share Fossilization conditions with younger BST deposits that are capable of preserving non-mineralizing metazoans. Thus metazoans, at least those typically preserved in BST deposits, were probably absent from sedimentary environments before approximately 800 Ma

  • A mineralogical signature for Burgess Shale–type Fossilization
    'Geological Society of America', 2018
    Co-Authors: Rp Anderson, Nj Tosca, Rr Gaines, Mongiardino Koch N, Briggs Deg
    Abstract:

    Burgess Shale-type (BST) Fossilization of carbonaceous remains that are ordinarily lost to decay is critical to our understanding of the early evolution of complex life. Sediment composition, particularly the abundance of certain clay minerals, has been invoked as a significant factor in BST Fossilization. X-ray diffraction data for 213 Cambrian shales from 19 sedimentary successions on four continents provide the first comprehensive test of the association of clay mineral assemblages with BST fossils. Samples containing BST fossils yield mineralogical compositions that form a subset within the range represented by samples containing only fossil mineralized skeletons. Logistic regression and classification tree methods reveal that BST fossils are more likely to be found in sediments rich in berthierine/chamosite and poor in celadonite and illite. This characteristic clay mineralogy probably reflects a high kaolinite/smectite ratio in the original sediment and enhanced iron availability during early diagenesis. Models derived from both methods can predict the occurrence of BST fossils in fossiliferous samples based on clay mineralogy with ~80% accuracy, providing a mineralogical signature that may be useful in refining the search for BST fossils on Earth and beyond