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No Slide Title Precambrian Fossils Geology 331, Paleontology The “Precambrian” is 87% of earth history. Components of Life 5 Principal components for all life: Water Carbohydrates: starches and sugars for energy Fats: for energy storage Proteins: structural tissues Nucleic acids: for reproduction 6 Dominant Elements of Life All present in the atmosphere, except P. H, hydrogen O, oxygen C, carbon N, nitrogen P, phosphorous (in rocks) S, sulfur Combining Elements into complex Organic compounds • Miller’s 1953 experiment: Combine gases of the early atmosphere in a sealed system with no oxygen. Heat the gases, add electrical sparks, cool the mixture. Amino acids formed after several days. They are the building blocks of protein. Combining Elements into complex Organic compounds • Miller combined CO2, NH3 (ammonia), CH4 (methane), and H2 • Added electrical spark, plus cooling • Formed amino acids, e.g. Serine C3H7NO3 Miller’s apparatus for creating amino acids from simple compounds in an anoxic atmosphere. Miller’s experimental apparatus -- note the black organics in the spark chamber Combining Elements into complex Organic compounds Several variations of Miller’s experiment have been run. These experiments have produced carbohydrates, fats, simple proteins, and the building blocks of nucleic acids: sugars, phosphates, and nitrogenous bases that form nucleotides (ATCG). The 5 Major Biochemical Steps in the Evolution of Life 1. Fermentation – archaea Sugar ethyl alcohol + 2 units of energy (ATP molecules) 2. Methane production – archaea CO2 + 4H2 CH4 + 2 H20 + 1 unit of energy (ATP molecule) The 5 Major Biochemical Steps in the Evolution of Life 3. Anaerobic photosynthesis – bacteria, 3.5 Ga? H2S + CO2 sugar + water + sulfur uses sunlight for energy 4. Aerobic photosynthesis - bacteria, 2.6 Ga H20 + CO2 sugar + O2 uses sunlight for energy The 5 Major Biochemical Steps in the Evolution of Life 5. Aerobic respiration - bacteria and eukarya, early Proterozoic, around 2.4 Ga? Sugar + O2 H20 + CO2 + 36 units of energy (ATP molecules) Prokaryotic cell vs. Eukaryotic cell The 3 Primary Branches of Life Prokaryotes: Bacteria on the tip of a pin. False colorized. Eukaryotes: Protozoans in pond water Hot springs at Yellowstone National Park. Analog for the early earth? Anaerobic photosynthetic archaea in boiling mud Sulfur crust Populations of archaea and bacteria in hot springs, Yellowstone National Park Sampling Organisms from Hot Springs Endosymbiosis Fossil Cell? 3.8 BY old from Greenland Modern stromatolites produced by cyanobacteria, Sharks Bay, Australia Modern stromatolites produced by cyanobacteria, Sharks Bay, Australia Fossil stromatolites, Great Slave Lake, Canada, 2.5 BY old Modern stromatolites or microbialites, Bahamas Cyanobacteria, makers of stromatolites since 2.6 Ga Microscopic views Cyanobacteria, makers of stromatolites 1.0 Ga Cyanobacteria fossils, 1 Ga Microscopic views Aug. 2011 A collection of tubular microfossils found in 3.4-billion-year-old sandstone from Western Australia. http://www.nytimes.com/2011/08/22/science/earth/22fossil.html?_r=1&emc=eta1 3.5 Ga Australia, cyanobacteria or not? Hotly debated Microscopic views Stromatolite, 3.5 Ga, Australia Closeup of stromatolite layers in last slide Stromatolites, 2 Ga, Minnesota Stromatolites, 2 Ga, Minnesota Stromatolites, 2 Ga, Minnesota Modern Fossil bacteria, bacteria 3.2 Ga from Africa Fossil bacteria 2 Ga from Minnesota Banded Iron Formations are the World’s primary source of iron ore. A piece of Banded Iron Formation, 2 Ga Iron Mine, Minnesota Iron Mine, Minnesota Banded Iron Formations, BIFs • Fe+2, reduced iron; Fe+3, oxidized iron • 2Fe + O2 2FeO ferrous oxide, soluable • 2FeO + 1/2O2 Fe2O3, ferric oxide, rust • FeO + Fe2O3 Fe3O4, magnetite • Between 3.5-2.0 Ga, the oceans “rusted”. Bands of iron oxide (summer) alternate with silica (winter). The oldest-known macrofossil, Grypania spiralis, a eukaryotic algae from 2.1 Ga. Plant-Animal or Heterotroph-Autotroph Dichotomy shows the Origin of Eukaryotes >2.1 Ga Protozoans and True Algae and Animals (0.6 Ga) Plants Was the 1.5 BY Grypania, 2.1 Ga delay in the evolution of animals required to evolve the nerve cell? . Chloroplasts from cyanobateria Mitochondria from purple bacteria . Origin of Eukaryotes Eukaryotic fossils, about 800 Ma, protozoans (testate amoebas) on left, microalgae on right The Doushantuo microfossils from China, 600 Ma Fig. 1. Images of Doushantuo microfossils showing evidence for cellular preservation, Neoproterozoic, 580 - 600 m.y. old Oldest Bilaterian and Triploblastic animal J.-Y. Chen et al., Science 306, 1291b (2004) Published by AAAS Fig. 2. A deep focal plane image of the holotype specimen of Vernanimalcula, Neoproterozoic, 580 - 600 m.y. old Oldest Bilaterian and Triploblastic animal J.-Y. Chen et al., Science 306, 1291b (2004) Published by AAAS Vernanimalcula, About the size of a oldest bilaterian period at the end of a sentence. University of Southern California paleontologist David Bottjer (Ph.D., Indiana University) was part of the team that made the fossil discovery of Vernanimalcula in China. Life of the Ediacaran, 543-600 Ma The White Sea assemblage, 560-550 Ma Australian outcrops with Ediacaran fossils Ediacaran fossils exposed in sandstone Modern sea pens, relatives of corals A fossil sea pen from the Ediacaran of Australia Mawsonites, a fossil jellyfish? A variety of Ediacaran fossils Dickinsonia – a segmented worm Kimberella – a probable mollusc Spriggina – an arthropod? Tribrachidium – what is it? Arkarua – oldest echinoderm? Rangeomorphs from Newfoundland Aspidella from Newfoundland Charnia Charniodiscus Cloudina Calcified organisms Namacalathus at the end of the reconstructed Ediacaran Late Proterozoic trace fossils Equatorial Marinoan diamictites and cap carbonates in Namibia Calcite crystal fans in a Cap Carbonate grew out of the sea floor, indicating high levels of CO2 Alan J. Kaufman Nature 450, 807-808(6 December 2007) The Cryogenian Period – Snowball Earth What role did it play in the evolution of metazoans? • The Cryogenian (Greek: cryos "cold" and genesis "birth") Period: 850–635 Ma • Somehow, we went from this… • To this… Snowball Earth! .
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