11-ch15-history-1

11-ch15-history-1 - Chapter 15 Tracing Evolutionary History...

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Chapter 15 Tracing Evolutionary History
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The fossil record chronicles life on earth fossil record (mostly in sedimentary rock) is incomplete but nonetheless useful. .. - relative dating by strata - calibrate with index fossils hard-bodied marine animals radiometric dating -- estimate age of rocks & fossils on a scale of absolute time, based on the half-life of radioactive isotopes half-life -- number of years for 50% of isotope sample to decay
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theory of plate tectonics -- earth crust divided into plates; geologic events at boundaries Pangaea -- supercontinent formed near end of Paleozoic era when plate movements brought all landmasses together Continental Drift
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Lungfish distribution, a result of continental drift current distribution of lungfish species: South America, Africa, Australia fossil lungfishes found on six continents these appear to be closely related (homology) lungfish evolved while Pangea was intact
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Also consider the marsupials The pattern of continental mergings and separations solves many puzzles, including Australia’s great diversity of marsupials, which probably originated in North America and spread southward while the continents were still joined. The subsequent breakup of continents set
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11-ch15-history-1 - Chapter 15 Tracing Evolutionary History...

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