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Life in the Precambrian

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					                    Pre-Phanerozoic Life

•      Origin of Life on Earth (= biopoesis; 4.0 - 3.8 Ga)
•      Advent of photosynthesis (3.8 - 3.5 Ga)
•      Aerobic (Oxygen-based) Respiration (3-2 Ga)
•      Eukaryotes / Endosymbiosis (2.1-1.6 Ga)
•      Sex / Death (1.2 - 1 Ga)
•      Multicellular Life (1,000 - 800 MYA)
•      Hard Part Skeletons & Shells (600 MYA)


Michael A. Gibson
TennMaps 2007
Origin of life on Earth = Biopoesis




Stromatolites – Cyanobacterial/microbial communities;
1st occurrence in Archean, dominates Proterozoic Eons
    Organic Compound Formation:
   Amino Acid Formation: Where?
1. “Warm Pond”   2. Hydrothermal Vents




                  3. Space (Panspermia)
             Isua Supergroup

    Oldest
  Evidence of
     Life:
not fossils, but
    organic
  byproducts

     Isua
  Supergroup
  Greenland
   (3.8 Ga)
Oldest Fossils:
 Apex Chert,
  Australia
   (3.5 Ga)
    Apex
Chert Fossils
  (3.5 Ga)




 Filamentous
   Bacteria
 1st Photosynthetic Organisms:
Cyanobacteria from Apex Chert

                     3.5 Ga (Archean)
                      Cyanobacteria
                     from Apex Chert
Formed Stromatolites
   Stromatolites
Mats of Cyanobacteria
North Pole, Australia
Stromatolite (3.5 Ga)
                  1.9 Ga (Proterozoic)




Gunflint Formation, Canada
What is Evidence of O2 Increase?




BIF’s = Earth Started to Rust
Eukaryotes & Endosymbiosis
                    Chuaria circularis
                      800 Mya


                                          Fossil Acritarch
                                         1st Appear 1.6 Ga




  Tawuia dalensis
Oldest Eukaryote
   Grypania spiralis
            1.3 Ga




                       2.1 Ga
                        Endosymbiosis
Free-living Prokayote

      Bacteria          Bacteria: Future Mitochondria

    Primitive
   Eukaryote




        Nucleus
Prokayotes
                    Endosymbiosis
 Cyanobacteria
                      Sequence
   Bacteria

 Primitive
Eukaryote        Mitochondria    Chloroplast




                          Modern
     Nucleus             Eukaryote
  Evidence for Endosymbiosis
                                 Evidence
                                 • Double Membrane
Eukaryote                        • DNA & Ribosomes
                                   (simplified)
                                 • Genetic Sequencing

                 Chloroplast



  Mitochondria


                       Nucleus
                       Endosymbiosis
Coral Polyps
                          Today

                      Zooxanthellae




       Note:
 Evolution involves
     Mergers…
 Some traits come
  “Prepackaged”
Multicellular Animal Embryos
Doushantuo Formation, China




         Fossil Embryo from
             Neoproterozoic
Ediacara Hills, Australia




             Dickinsonia
Ediacaran Fauna




                  Spriggina floundersi
Ediacaran Seafloor
          Hard Part Formation:
          Skeletons and Shells

Small Shelly Fossils
      (SSF’s)
 Tommotian Fauna
       CaPO4
Cambrian Explosion
Summary Timing of Life on Earth

          1st Photosynthesis & Stromatolites

4.6 Ga                                                 Today

No Life            Single Celled Life Only

                                               Multi-Celled
                                                   Life
                        1st Eukaryotes       1st Sex
       O2 Revolution
     Aerobic Respiration

				
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posted:12/3/2011
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