Ch 25 - The history of life on earth (1 slide per page)-2

Adaptive radiation 2 continental drift 3 mass

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Unformatted text preview: ing the rise and fall of groups of organisms 1. Adaptive Radiation 2. Continental Drift 3. Mass Extinction 80 Extinction Background extinction: A few species lost on an ongoing basis Mass extinction: • > 60% of species • different lineages go extinct at approx. same time Quaternary ~5-6 major extinction events in Earth’s history 81 Permian Mass Extinction (~250 Mya) Largest mass extinction event ever: ~95% of living species go extinct! Associated with very rapid warming of climate. Causes? • Massive volcanism? • Frozen CH4 released from seabeds (=positive feedback)? 82 Permian Mass Extinction Extinct: Heavy losses: Crinoids Trilobites Brachiopods Opened up opportunities for surviving organisms: Adaptive radiation! 83 Cretaceous Mass Extinction (65 Mya) 75% - 85% of species lost • Asteroid or comet impact (Chicxulub crater) • No long-term climate shift 84 Cretaceous Mass Extinction Extinct: Heavy losses: Ammonoids Mosasaurs Photosynthetic organisms (algae, land plants) Large land animals (dinosaurs, marsupials) Result: Adaptive radiation! 85 Adaptive Radiations often follow major extinctions...
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This note was uploaded on 02/12/2014 for the course BIOLOGY 2011 taught by Professor Woo during the Fall '10 term at University of Central Florida.

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