Mass ExtinctionsMass Extinctions

Evidence for Many Events over Evidence for Many Events over Geological HistoryGeological History

Potential Triggers

Asteroid Impacts = sudden

Large Basalt Outflows

Large CO2 changes which can affect atmospheric and ocean chemistry (slow)

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

At least a dozen eventsAt 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.

Periodic Extinctions of Varying Periodic Extinctions of Varying Amplitude (percent extincted)Amplitude (percent extincted)

Mass Extinctions and EvolutionMass Extinctions and Evolution

½ to 2/3 of all species are eliminated during ½ to 2/3 of all species are eliminated during big eventsbig events

Plankton in the ocean is nukedPlankton in the ocean is nuked So both the land and water are effectedSo both the land and water are effected Encephelization Levels (Encephelization Levels (EL) in organisms ) in organisms

measure the amount of brain tissue in measure the amount of brain tissue in excess of that needed for basic metabolism excess of that needed for basic metabolism maintenancemaintenance

Evolution of Intelligence?Evolution of Intelligence?

This diagram has many features: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

ImplicationsImplications Evolutionary Clock gets resetEvolutionary Clock gets reset Life recovers (relatively rapidly) to fill Life recovers (relatively rapidly) to fill newnew

ecological niches ecological niches this empowers species this empowers species diversificationdiversification

This means that “survival of the fittest” This means that “survival of the fittest” doesn’t work on long timescales doesn’t work on long timescales random random catastrophe importantcatastrophe important

Strangely, nature confirms that a “new Strangely, nature confirms that a “new world will arrive out of the ashes of the old world will arrive out of the ashes of the old one”one”

This will happen again (right after the final)This will happen again (right after the final)