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Precambrian Era

Precambrian Era

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Precambrian Era

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  1. Precambrian Era Simple life starts in the oceans 4,600,000,000 years ago to 570,000,000 years ago 85% of Earth’s History

  2. The Earth Forms

  3. 4.6 BYA A molten Earth forms Surface cools, forming the crust • Oldest rock found in Western Australia • primitive atmosphere forms from volcanic eruptions (No Free oxygen gas). • Oceans form (from water vapor released in eruptions & maybe comets) 4.3 BYA

  4. Comparison of Atmospheres

  5. 3.5 BYA Oldest fossils of bacteria (prokaryotes). • Simple & small with no nucleus

  6. Miller/Urey Experiment (1953) • Tried to create life from a simulated primitive atmosphere. • Instead created complex molecules, but no cells.

  7. What does it mean to be living? • Be able to reproduce • Uses energy • Composed of one or more cells • Contains genetic information

  8. Where did Life Start? • Oceans(nutrient rich, possibly with complex molecules) • Ice(opportunity for organization) • Meteorites(rich with building blocks of life)

  9. First Cells? complex molecules (RNA) replicating inside coacervates (similar to cell membrane).

  10. 3.0 BYA Cyanobacteria (blue-green algae) evolve • creates energy from photosynthesis • giving off oxygen gas (beginning to form the atmosphere of today). • Form large stromatolites (below)

  11. 1.5 BYA • Eukaryotes (complex, larger, single celled organisms) evolve from prokaryotes (bacteria).

  12. 630 MYA • Multicellular organisms evolve with soft bodies Species include: jelly fish; coral stalks; segmented worms; algae