1. Precambrian Time 4,600,000,000 yrs ago to 570,000,000 yrs ago
85% of Earth’s History!!
Simple Life starts in the oceans

2. The center of Earth was melted by great pressure and intense heat.
Oldest rock found in Western Australia
An atmosphere formed as Earth cooled.
primitive atmosphere forms from volcanic eruptions
Did NOT contain oxygen gas
Oceans form from water vapor released in eruptions & maybe comets
4.1BYA The surface of Earth cooled forming the crust
The Earth Forms
6 BYA The Solar system formed from swirling gases and dust
4.5BYA Rocks in the solar system condensed to form Earth

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

4. Comparison of Atmospheres

5. Hydrothermal Ocean Vents
Where did Life Start?
Hydrothermal Ocean Vents
nutrient rich, possibly with complex molecules which may have joined together to form structures such as cells
Ocean covered in Ice
extra protection from UV radiation and opportunity for organization
Meteorites or Comets
rich with building blocks of life

6. 3.5 BYA Precambrian Time Oldest fossils of bacteria (prokaryotes).
Simple and small
Lack a nucleus
Do not need oxygen to survive

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

8. 3.0 BYA Precambrian Time Cyanobacteria (blue-green algae) evolve
creates energy from photosynthesis
gives off oxygen gas (beginning to form the atmosphere of today)
Form large stromatolites (below)

9. 1.5 BYA Precambrian Time Eukaryotes contain a nucleus
more complex, larger, single celled organisms
Evolved from prokaryotes

10. 630 MYA Precambrian Time
Multicellular organisms evolve with soft bodies
Species include: jelly fish; coral stalks; segmented worms; algae