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Proterozoic Eon 2.5 bya – 570 mya

Proterozoic Eon 2.5 bya – 570 mya. Photosynthesis transforms E and anaerobic procaryotic world Oxygen Revolution- full scale Stromatolites everywhere first abundant “fossils” of living organisms, mostly bacteria and archeans 2.1 bya - Eukaryotic cells evolve

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Proterozoic Eon 2.5 bya – 570 mya

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  1. Proterozoic Eon2.5 bya – 570 mya • Photosynthesis transforms E and anaerobic procaryotic world • Oxygen Revolution- full scale • Stromatolites everywhere • first abundant “fossils” of living organisms, mostly bacteria and archeans • 2.1 bya - Eukaryotic cells evolve • Mid Proterozoic, Iron formation max as O2 builds up • Spells doom for earlier life forms; makes possible explosion of eukaryotic forms, include multicellular - algae, and toward end, first animals. • Shields accrete to stable continents “rocked” by plate tectonics

  2. Cyanobacteria Rules! Earth is Scummy!

  3. Stromatolites everywhere and surface is multicolored mats of slime!

  4. Oxygen Revolution Reaches Peak around 2.1 bya • Photosynthetic life - primarily in the form of phytoplankton – cranking out O2 since 3.5 bya (first stromatolites). • Photosynthesis=metabolic process (organisms use sunlight, CO2 and H2O to make energy) • O2 is waste product of photosynthesis; essential to the metabolic processes used by animals.

  5. Banded Iron Formations 2.5-2 bya • 2.5 bya: banded iron formations, from build up of oxygen, appear

  6. Evolution Leaps Forward with Emergence of Eucaryotes • Took over a billion years of change • Evolution of life takes a huge leap with a new “domain” of life • Bigger leap than differences between plants and animals

  7. Eucaryotic Cell Evolves (Coincides with Rise in O2?) • Photosynthetic procaryotes create stromatolite “cities”: waste leads to oxygen revolution, 2.2-2.1 bya • Cells with nuclei evolve – eucaryotes (2.2-2.1 bya) • Coincides with build-up of oxygen?

  8. Eucaryotic cells (2.1 bya?) • Mitochondria may be formerly free existing cyanobacteria, now incorporated into the cell of a eucaryote (with nucleus) • Mitochondria is “energy factory” for eucaryotic • Eucaryotic cells builds protists, algae, fungi, plants, lichen (fungi and algae)

  9. Microbial “Tracks and Trails” • Signs of life - different type of fossil • Microfossils - activities of microbes (not worms!) • Not organisms themselves but “traces”of their movements, existence • Some chemical footprints • Captured in chert - sedimentary rocks, and stromatolites

  10. Land masses growing and continents forming

  11. Rodinia Breaks Up • 1.2 bya continents smash together and form Rodinia • Supercontinent Rodinia lasts 350 my • 750 mya, Rodina breaks up • the atmosphere may have contained less than 5% of the oxygen it now holds, and it lacked the protective ozone layer

  12. Sponges Form (modern ones shown) • Primitive multicellular animals

  13. Late Proterozoic 650 mya

  14. Snowball Earth 600-700 mya • Earth rocks backs and forth between complete/near complete ice ages • Namibian rock formations • earth covered in ice • Pattern in cliffs of rocks forming in cold climates interspersed with rocks forming in hot climates….

  15. Edicarian Life Forms - Disappear and Don’t “Make It” • 600mya (?) first animals emerge - but these all go extinct • “Edicarian” animals • “Strange” life fossils discovered in shale - Australia, New Foundland • Ozone layer probably established

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