1. Mass Extinctions Evidence for Many Events over Geological History

2. Potential Triggers   Asteroid Impacts = sudden

3. Large Basalt Outflows   Large CO 2 changes which can affect atmospheric and ocean chemistry (slow)

4. Periodic Comet Strikes   Fossil record shows some 26-27 million year period of some extinction event (usually small)   Nemesis Theory (likely not correct)   On the time scale of 20-30 million years (1/10 of our galactic orbit) – nearby stars could perturb our Oort cloud of Comets

5. At least a dozen events The concept of impact induced extinction events is relatively new – first evidence came in 1980 regarding the KT event (65 million years ago – dead dinosaurs). Further research and data have no shown that such events are common.

6. Periodic Extinctions of Varying Amplitude (percent extincted)

7. Mass Extinctions and Evolution  ½ to 2/3 of all species are eliminated during big events  Plankton in the ocean is nuked  So both the land and water are effected  Encephelization Levels (EL) in organisms measure the amount of brain tissue in excess of that needed for basic metabolism maintenance EL

8. Evolution of Intelligence?  This diagram has many features: Fastest Growth: 600-250 MYA; beginning of sea to land migration Last 200 million years has constant slope Unaltered EL Evolution would have produced “humans” 60 MYA EL Doubling time About 2 MY

9. Implications Evolutionary Clock gets reset Evolutionary Clock gets reset Life recovers (relatively rapidly) to fill new ecological niches  this empowers species diversification Life recovers (relatively rapidly) to fill new ecological niches  this empowers species diversification This means that “survival of the fittest” doesn’t work on long timescales  random catastrophe important This means that “survival of the fittest” doesn’t work on long timescales  random catastrophe important Strangely, nature confirms that a “new world will arrive out of the ashes of the old one” Strangely, nature confirms that a “new world will arrive out of the ashes of the old one” This will happen again (right after the final) This will happen again (right after the final)