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About how long ago did the earth first form?
4.6 Billion Years Ago
What did earth look like 3.8 bya?
- First life on earth appeared.
- Very little oxygen on earth.
- The physical environment was very different than now.
What did the earth look like 2.5-0.5 bya?
- Oxygenation of oceans and atmosphere.
- All organisms that existed earth were prokaryotic.
What did earth look like 1.5 bya?
- Eukaryotic organisms appeared.
- The use of oxygen/mitochondria.
What happened 542 mya?
The Cambrian "Explosion" occured where diversity of life formed rapidly over roughly 50 million years.
What happened during the Cambrian Explosion?
- Atmospheric oxygen levels=HIGH(first chordates)
- Invasion of land
- Giant flying insects
- First flowering plants(angiosperms)
- Oxygen levels dropped and there was a mass extinction!
The Ordivician period
During the Ordivician period there was massive marine diversification, plants first moved to land and vascular plants arrived.
The Devonian period
During the Devonian period invertebrates became well-established on land, land plants diversified massively and seed plants appeared. There was a massive MARINE extinction that ended the Devonian period.
The Permain period
96% of multicellular species were wiped out
The Cretaceous period
- Angiosperms appeared at the end of the Jurrasic and diversify
- Extinction event marks the beginning of modern biota
The Cenozoic period
- Mammals diversify
- Angiosperms are dominant
- The Homo species appears
The order of periods from oldest to most recent
Cambrian, Ordivician, Devonian, Permian, Cretaceous, Cenozoic
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