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A2 Past Life (Edicaran (565 million years ago) (soft bodied animals found…
A2 Past Life
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Vertebrates
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Silurian- Ostracoderms evolved then by the end of the Silurian the placoderms evolved which had jaws
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Snowball Earth
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Role in evolution
Nutrient rich melt water flooded into the oceans which acted as a fertilizer for photosynthesis so the sinobacetria pumped out oxygen.
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- first organisms were simple-one celled organisms (3900 million)
- Earth's atmosphere was composed of volcanic gas (CO2, N2, H2O)
- first fossil was found 3500 years ago
- known as stromatolites which are still around today in Shark Bay Australia
- they created O2 as a by-product so it began to accumulate slowly as a by product in the atmosphere
- In the atmosphere, oxygen is broken down by ultraviolet radiation into O which in turn forms ozone or O3
- first multi-cellular life-form was a sponge
