Now showing items 1-20 of 202

    • Accelerating Neoproterozoic research through scientific drilling 

      Condon, D. J.; Boggiani, P.; Fike, D.; Halverson, G. P.; Kasemann, S.; Knoll, Andrew Herbert; Macdonald, Francis Alexander; Prave, A. R.; Zhu, M. (Copernicus GmbH, 2015)
    • Acritarchs and Microfossils from the Mesoproterozoic Bangemall Group, Northwestern Australia 

      Buick, Roger; Knoll, Andrew Herbert (Paleontological Society, 1999)
      Three microfossil assemblages occur in the Mesoproterozoic Bangemall Group (1625-1000 Ma) of northwestern Australia, each occupying a different environmental and taphonomic setting. In peritidal environments, benthic ...
    • Ambient Pyrite in Precambrian Chert: New Evidence and a Theory 

      Knoll, Andrew Herbert; Barghoorn, Elso S. (National Academy of Sciences, 1974)
      Ambient pyrites of two distinct types were described from middle Precambrian rocks of the Lake Superior area. A new class of this phenomenon is here described from middle Precambrian chert from western Australia. The newly ...
    • Anatomical and Ecological Constraints on Phanerozoic Animal Diversity in the Marine Realm 

      Bambach, Richard; Knoll, Andrew; Sepkoski, J. John Jr (National Academy of Sciences, 2002)
      We grouped the fossil records of marine animal genera into suites defined by function and physiology, The stratigraphic coherence of the resulting diversity history indicates the importance of ecological structure in ...
    • Ancient Aqueous Environments at Endeavour Crater, Mars 

      Arvidson, R. E.; Squyres, S. W.; Bell, J. F.; Catalano, J. G.; Clark, B. C.; Crumpler, L. S.; de Souza, P. A.; Fairen, A. G.; Farrand, W. H.; Fox, V. K.; Gellert, R.; Ghosh, A.; Golombek, M. P.; Grotzinger, J. P.; Guinness, E. A.; Herkenhoff, K. E.; Jolliff, B. L.; Knoll, Andrew Herbert; Li, R.; McLennan, S. M.; Ming, D. W.; Mittlefehldt, D. W.; Moore, J. M.; Morris, R. V.; Murchie, S. L.; Parker, T. J.; Paulsen, G.; Rice, J. W.; Ruff, S. W.; Smith, M. D.; Wolff, M. J. (American Association for the Advancement of Science (AAAS), 2014)
      Opportunity has investigated in detail rocks on the rim of the Noachian age Endeavour crater, where orbital spectral reflectance signatures indicate the presence of Fe+3-rich smectites. The signatures are associated with ...
    • Ancient Impact and Aqueous Processes at Endeavour Crater, Mars 

      Knoll, Andrew Herbert; Squyres, S. W.; Arvidson, R. E.; Bell, J. F., III; Calef, F., III; Clark, B. C.; Cohen, B. A.; Crumpler, L. A.; de Souza, P. A., Jr.; Farrand, W. H.; Gellert, R.; Grant, J.; Hurowitz, J. A.; Herkenhoff, K. E.; Johnson, J. R.; Jolliff, B. L.; Li, R.; McLennan, S. M.; Ming, D. W.; Mittlefehldt, D. W.; Parker, T. J.; Paulsen, G.; Rice, M. S.; Ruff, S. W.; Schröder, C.; Yen, A. S.; Zacny, K. (American Association for the Advancement of Science, 2012)
      The rover Opportunity has investigated the rim of Endeavour Crater, a large ancient impact crater on Mars. Basaltic breccias produced by the impact form the rim deposits, with stratigraphy similar to that observed at ...
    • Animals in a Bacterial World, A New Imperative for the Life Sciences 

      McFall-Ngai, M.; Hadfield, M. G.; Bosch, T. C. G.; Carey, H. V.; Domazet-Loso, T.; Douglas, A. E.; Dubilier, N.; Eberl, G.; Fukami, T.; Gilbert, S. F.; Hentschel, U.; King, N.; Kjelleberg, S.; Knoll, Andrew Herbert; Kremer, N.; Mazmanian, S. K.; Metcalf, J. L.; Nealson, K.; Pierce, Naomi E.; Rawls, J. F.; Reid, A.; Ruby, E. G.; Rumpho, M.; Sanders, Jon Gregory; Tautz, D.; Wernegreen, J. J. (Proceedings of the National Academy of Sciences, 2013)
      In the last two decades, the widespread application of genetic and genomic approaches has revealed a bacterial world astonishing in its ubiquity and diversity. This review examines how a growing knowledge of the vast range ...
    • Anomalous Carbonate Precipitates: Is the Precambrian the Key to the Permian? 

      Grotzinger, John P.; Knoll, Andrew (Society for Sedimentary Geology, 1995)
      Late Permian reefs of the Capitan complex, west Texas; the Magnesian Limestone, England; Chuenmuping reef, south China; and elsewhere contain anomalously large volumes of aragonite and calcite marine cements and seafloor ...
    • Anoxygenic Photosynthesis Modulated Proterozoic Oxygen and Sustained Earth’s Middle Age 

      Johnston, David T; Wolfe-Simon, Felisa Lauren; Pearson, Ann; Knoll, Andrew Herbert (National Academy of Sciences, 2009)
      Molecular oxygen (O2) began to accumulate in the atmosphere and surface ocean ca. 2,400 million years ago (Ma), but the persistent oxygenation of water masses throughout the oceans developed much later, perhaps beginning ...
    • Archean Microfossils Showing Cell Division from the Swaziland System of South Africa 

      Knoll, Andrew; Barghoorn, Elso S. (American Association for the Advancement of Science, 1977)
      A newly discovered population of organic walled microstructures from the Swaziland System, South Africa, is considered to be biological on the following grounds: (i) the structures are carbonaceous and occasionally have ...
    • Archean Photoautotrophy: Some Alternatives and Limits 

      Knoll, Andrew (Springer, 1979)
      From the Archean geological record, one can infer that photoautotrophy evolved early in earth history; however, the nature of this photosynthesis - whether it was predominantly bacterial or cyanobacterlal - is tess clearly ...
    • An Astrobiological Perspective on Meridiani Planum 

      Wdowiak, Thomas; Tosca, Nicholas J.; Squyres, Steven; Schroder, Christian; Malin, Michael; McLennan, Scott M.; Grotzinger, John P.; Fischer, Woodward W.; Farmer, Jack D.; Des Marais, David J.; Clark, Benton; Carr, Michael; Knoll, Andrew Herbert (Elsevier, 2005)
      Sedimentary rocks exposed in the Meridiani Planum region of Mars record aqueous and eolian deposition in ancient dune and interdune playa-like environments that were arid, acidic, and oxidizing. On Earth, microbial populations ...
    • A Bangiophyte Red Alga from the Proterozoic of Arctic Canada 

      Butterfield, Nicholas J.; Knoll, Andrew; Swett, Keene (American Association for the Advancement of Science, 1990)
      Silicified peritidal carbonate rocks of the 1250- to 750-million-year-old Hunting Formation, Somerset Island, arctic Canada, contain fossils of well-preserved bangiophyte red algae. Morphological details, especially the ...
    • A Basin Redox Transect at the Dawn of Animal Life 

      Sperling, Erik A.; Halverson, Galen P.; Knoll, Andrew Herbert; Macdonald, Francis Alexander; Johnston, David T (Elsevier BV, 2013)
      Multiple eukaryotic clades make their first appearance in the fossil record between ~810 and 715 Ma. Molecular clock studies suggest that the origin of animal multicellularity may have been part of this broader eukaryotic ...
    • Biologically Induced Initiation of Neoproterozoic Snowball-Earth Events 

      Tziperman, Eli; Halevy, Itay; Johnston, David T; Knoll, Andrew Herbert; Schrag, Daniel P. (Proceedings of the National Academy of Sciences, 2011)
      The glaciations of the Neoproterozoic Era (1,000 to 542 MyBP) were preceded by dramatically light C isotopic excursions preserved in preglacial deposits. Standard explanations of these excursions involve remineralization ...
    • Biomarker Evidence for Green and Purple Sulphur Bacteria in a Stratified Palaeoproterozoic Sea 

      Brocks, Jochen J.; Love, Gordon D.; Summons, Roger E.; Knoll, Andrew; Logan, Graham A.; Bowden, Stephen A. (Nature Publishing Group, 2005)
      The disappearance of iron formations from the geological record similar to 1.8 billion years (Gyr) ago was the consequence of rising oxygen levels in the atmosphere starting 2.45 - 2.32 Gyr ago. It marks the end of a 2.5-Gyr ...
    • Biostratigraphic and Chemostratigraphic Correlation of Neoproterozoic Sedimentary Successions: Upper Tindir Group, Northwestern Canada, as a Test Case 

      Kaufman, Alan J.; Knoll, Andrew; Awramik, Stanley M. (Geological Society of America, 1992)
      Recent advances in Proterozoic micropaleontology and sedimentary isotope geochemistry suggest that improved interbasinal correlation of Neoproterozoic (1000-540 Ma) successions is possible. Because widely varying interpretations ...
    • The Biotic Crisis and the Future of Evolution 

      Myers, Norman; Knoll, Andrew (National Academy of Sciences, 2001)
      The biotic crisis overtaking our planet is likely to precipitate a major extinction of species. That much is well known. Not so well known but probably more significant in the long term is that the crisis will surely disrupt ...
    • A bottom-up perspective on ecosystem change in Mesozoic oceans 

      Knoll, Andrew H.; Follows, Michael J. (The Royal Society, 2016)
      Mesozoic and Early Cenozoic marine animals across multiple phyla record secular trends in morphology, environmental distribution, and inferred behaviour that are parsimoniously explained in terms of increased selection ...