PNB 2250 Lecture Notes - Lecture 2: Devonian, Great Oxygenation Event, Hyperoxia
10 Nov 2016
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Document Summary
Life shaped the earth and the earth shaped life. Ecosystem engineers: atmospheric composition, ocean acidification, global distribution of new materials. 3. 4 billion years ago: prokaryotic organisms started to become photosynthetic. Marine photosynthesis phytoplankton: oxygen oxidized everything. The great oxygenation event: 2. 4 billion years ago, anaerobic planet became aerobic planet, enough oxygen in atmosphere to start building ozone layer, changed mineral composition of the ocean, oxidized (chemically burned) methane into co2. Neoproterozoic era: before cambrian explosion, were not simple animals, very complex ecosystems, lots of different species. Ancestors are not present on earth: cambrian explosion. Appearance of all animal phyla 540 million years ago. Ice ages interspersed with warm ages (50+ degrees c) Week 1 lecture 2 animal evolution wednesday 8/31/16. Volcanism: movement of mantle elements into biosphere. Increased calcium supply to potentially make fossils easier to form. Ca(cid:374)"t fi(cid:374)d soft tissue i(cid:374) fossil re(cid:272)ords. Ozone formation: 200-300 nm shield, uv-radiation barrier. Changes in evolution: animals developed gene duplication.
