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Life’s Origin and Evolution, Part II Hadean Eon (i.e., Hell on Earth) 4.5 - 3.8 Billion Years Ago Archaean Eon 3.8 - 2.5 Billion Years Ago Life in the Universe - Astrobiology Dr. R. L. Hudson (Fall, 2015) Endogenous Simple … to … Complex H2, He, CH4, NH3, H2O, CO2, N2 Molecules Type of Life: prokaryotic (bacteria) The Miller-Urey Experiment (1953) Can make amino acids and more Energy Credit: AccessExcellence.org Exogenous Meteorites And Comets Evolutionary Example: Earth’s Atmosphere H2, He, CH4, NH3, H2O, CO2, N2 CH4, NH3, H2O, CO2, N2 CO2, N2 1 Stromatolites (again) Rocks Change: CO2 falls and O2 rises Banded iron formations in rocks http://www.ga.gov.au/education/minerals/ironform.html Sunlight + CO2 O2 Photochemistry in the Upper Atmosphere O2 O + O O + O2 O3 Ozone Shield (6 - 30 miles up) Fully oxidized rocks ~ 2.5 billion years ago Earth Forms ~ 4.5 billion years ago Prokaryotes ~ 3.5 billion years ago Eukaryotes ~ 2 billion years ago Eukaryotic Fossils ~ 2 billion years ago Darwin’s gap ~ 0.5 billion years ago land animals hard shells http://evolution.berkeley.edu/ 2 The Cambrian Explosion Cambrian Explosion ~ 545 million years ago The Cambrian Explosion Charles Doolittle Walcott (1850 – 1927) Smithsonian Institution Secretary For More Information Charles Doolittle Walcott (1850 – 1927) Dr. Stephen Jay Gould (1941 – 2002) The Cambrian Explosion The Cambrian Explosion Charles Doolittle Walcott (1850 – 1927) Charles Doolittle Walcott (1850 – 1927) 5 miles south 3 Astrobiology Lesson Astrobiology Lesson Halophiles and methanogens - http://scitechdaily.com/researchers-may-be-able-to-sequence-genomes-of-any-microbes/ A Problem Meteor Crater (Arizona) ~ 50,000 years ago ~ 1 mile across Tunguska Event Comet Shoemaker-Levy 9 June 30, 1908 in Siberia 800 miles2 80 106 trees 4 hours past St. Petersburg July 18, 1994 4 Impact Craters Mass Extinction Dramatic, sharp rise in death of animal or plant life (or both) in a short period of time. Impacts! The K-T Impact ~ 65 million years ago Several identified over 550 106 years See organism below, but not above, a certain rock strata Two Pieces of Evidence Chicxulub Crater Mexico Iridium Layer Shocked Quartz ~ 100 miles in diameter ~ 65 millions years old (Not “Chicks-U-Love”) 5 Impact Crater In Mexico The Chelyabinsk Impact February 15, 2013 http://www.newyorker.com/news/news-desk/a-meteor-in-the-russian-sky The Chelyabinsk Impact February 15, 2013 Future Extinctions? Supernova events Gamma-ray bursters Stellar ejection of Earth Impacts Galactic oscillations (30 106 years) Massive Impacts Can Reset the Evolutionary Stage Dinosaurs – Goodbye Mammals – Hello Sources of Material Most of the images used here are either original, from our class’s textbook, or in the public domain. Material has been credited in cases where I knew the sources. I will be glad to add any credits missed. 6