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Unformatted text preview: Brief Highlights of Earth History 4600 – Origin of solar system – molten earth differentiates; first atmosphere from out gassing has no free oxygen 3500 – Earliest fossils – single celled bacteria, prokaryotic cell, no nucleus, asexual reproduction; anaerobic 2500 – Stromatolites become abundant, evolved probably 3500-3000mya, cyanobacteria are blue-green algae, prokaryotic but aerobic (photosynthetic) free oxygen builds in the atmosphere 2500-2000 – BIFs (banded iron formations) – 92% world’s iron ore, dissolved iron in oceans combines with oxygen to form iron oxide layers, algal blooms, +/- 1-% PAL (present atmospheric level oxygen) 1000 – Earliest eukaryotic cells recorded; nucleus = sexual reproduction; oxygen around means more aerobic organisms possible; diversity increases 670-570 – Ediacaran fauna – life’s failed experiment; soft-bodied organisms following a different path; two dimensional without mouth/anus 570-540 – Cambrian Explosion – rapid appearance and diversification of shelled organisms; predators...
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- Spring '11
- Bacteria, free oxygen, Ediacaran fauna, slope Topographic maps