Earth History

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Earth History

  1. 2. The Age of the Earth <ul><li>4.6 billion years old = </li></ul><ul><li>4,600,000,000 </li></ul>Image courtesy of NASA, http://en.wikipedia.org/wiki/Image:The_Earth_seen_from_Apollo_17.jpg#file
  2. 3. The earth’s 4.6 billion year history is divided into major units of time: Cenozoic Era Mesozoic Era Paleozoic Era Precambrian Time Image created by Jason Brechko for Lake George Association (Lake George, NY) http://www.lakegeorgeassociation.org/geology_facts.htm
  3. 4. Precambrian Time <ul><li>4.6 billion years before present to 544 million years before present </li></ul><ul><li>Longest era with a sparse fossil record </li></ul><ul><li>Origin of earth’s crust, first atmosphere, and first seas </li></ul><ul><li>Earliest fossils of cyanobacteria use photosynthesis to produce oxygen </li></ul><ul><li>Ozone layer in the atmosphere is formed from oxygen </li></ul>Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College. Image courtesy of http://www.sharkbay.wa.gov.au/tourism/what_to_see_and_do/images/stromatolites_lge.jpg
  4. 5. Paleozoic era <ul><li>544 million years before present to 245 million years before present </li></ul><ul><li>Marine communities flourish </li></ul><ul><li>Early fishes develop </li></ul><ul><li>Origin of amphibians, insects & reptiles </li></ul><ul><li>Recurring ice ages/ Appalachians mountains form </li></ul><ul><li>Spore-bearing plants dominate </li></ul>Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College. Images courtesy of: http://discover.edventures.com/images/termlib/p/paleozoic/support.gif , http://en.wikipedia.org/wiki/Trilobites
  5. 6. Paleozoic era (continued)… <ul><li>286 - 248 million years before present: Supercontinent of Pangea forms </li></ul><ul><li>248 million years before present: MASS EXTINCTION-90 % of all known families lost! </li></ul>Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College. c Image courtesy of http://www.ig.utexas.edu/research/projects/plates/teaching_ideas.htm?PHPSESSID=def1b9
  6. 7. Mesozoic Era <ul><li>245 million years before present - 65 million years before present </li></ul><ul><li>The age of the dinosaurs! </li></ul><ul><li>Gymnosperms dominate land plant/ origin of angiosperms - flowering plants </li></ul><ul><li>Origin of mammals & birds </li></ul><ul><li>145 million years before present - asteroid impact? MASS EXTINCTION </li></ul><ul><li>Pangea begins to separate/ Rocky mountains form </li></ul>Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College. Image courtesy of http://nascarulz.tripod.com/dinomain.html
  7. 8. 65 million years before present…. <ul><li>ASTEROID IMPACT! </li></ul><ul><li>Mass extinction of ALL dinosaurs and many marine organisms </li></ul><ul><li>End of the Mesozoic era </li></ul>Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College. Image courtesy of NASA: http://www.nasaexplores.com/show2_912a.php?id=01-074&gl=912
  8. 9. Cenozoic Era <ul><li>65 million years before present -today </li></ul><ul><li>Present era we live in </li></ul><ul><li>Continued evolution and adaptations of flowering plants, insects, birds, mammals </li></ul><ul><li>Mammals dominant </li></ul><ul><li>Major crustal movements & mountain building (Alps & Himalayan mountains form) </li></ul>Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College. Image courtesy of: http://www.karencarr.com/gallery_Cenozoic_arch.html
  9. 10. And during the Cenozoic era… <ul><li>The most primitive hominid (human ancestor) evolves - approximately 4.4million years before present </li></ul><ul><li>The first modern humans (homo sapiens) evolved approximately 100,000 years before present </li></ul>Image courtesy of: http://www.wilderdom.com/images/evolution/8.jpg

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