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Geological Evolution • Plate tectonics or Continental Drift Theory states… Earth’s surface is divided into plates that continually move, taking the continents with them Types of plate boundaries: Convergent: plates come together often forms mountain chains Divergent: plates separate causing faults (earthquake) Outline of separate tectonic plates found on Earth History of Plate Tectonics http://pubs.usgs.gov/gip/dynamic/historical.html Pangaea: 225 MYA- one super continent Laurasia & Gonwanaland: 200 MYA- Pangaea separated into 2 continents Today: 7 major continents due to plate movement Evidence: Polar Dinosaur Cryolophosaurus ellioti: fossils found in S. Australia and in Antarctica How does this relate to Life Science? – Climates change as… • Land moves away from equator • Land moves toward equator • Oceans/Seas disappear or appear • Mountain ranges form • New coastlines form – Biomes Change meaning… • Organisms must adapt to these changes • Beneficial adaptations will be passed on in successive generations thus changing the source of genes (natural selection) Evolution Clues – Homologous structures: body structures of different organisms that are similar in origin and structure • Forelimbs of chordate animals (animals w/ backbones) • http://evolution.berkeley.edu/evolibrary/article/similarity_ms_01 Questions: • • • • How are tetrapods’ limbs similar? What is an example of a plant homology? What is an analogous structure? Why might some structures evolve independently in various organisms? Other Evidence: • – Vestigial Structures: structures that have no known function • – In humans: tail bone and muscles around the ear Similar DNA: organisms of the same species generally share 99 - 99.9% same DNA • Various Primates of different species all share a common ancestor Trends in Evolution • http://evolution.berkeley.edu/evosite/evo101/VIIDTrends.shtml – How do complex structures like eyes evolve? http://evolution.berkeley.edu/evosite/evo101/VIICComplexity.shtml – What is a transitional form? http://evolution.berkeley.edu/evosite/lines/IAtransitional.shtml – What is “evolutionary opportunity”? ex. Dinosaur extinction leads to a rise in mammal species on Earth