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Today – 1/18

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  1. Today – 1/18 • Critter in the news / weather report • Reading background • End of the dinosaurs (?) • First writing assignment

  2. Possible test question Peter Ward and Roger Smith in Gorgon want: • To learn how mammals survived the end-Permian extinction event • Evidence of dinosaur ancestors • To determine if the Permo-Triassic extinction was sudden or gradual • All of the above

  3. Administration: • “Get to know you” form worth 2 pts XC • Ross’ OH in Gould-Simpson 205

  4. Turiasaurus • End of the Jurassic, 145 Ma • 100+ feet long! Almost 100,000 lbs! • sauropod - member of clade Sauropoda • Other super-giants like Brachiosaurus and Seismosaurus more closely related to each other than to Turiasaurus

  5. Last time: • Biostratigraphy – Principle of faunal succession • Mammal-like reptiles of the late Permian* • Mass extinctions

  6. http://darkwing.uoregon.edu/~millerm/meander.html Meandering river Braided streams /www.uky.edu/AS/Geology/howell

  7. Meandering v. braided stream: • Braided streams: networks of interconnected channels that form where there is a large sediment supply, large fluctuations in flow levels, erodable banks • Meandering river: think of large single channel slowly winding its way across a gently sloping plain. E.g. Mississippi R. Banks stabilized by well-established vegetation

  8. Carbon atom

  9. Carbon Isotopes • All carbon atoms have 6 protons • 98.9 % of carbon atoms have 6 neutrons, called C-12 • 1.1 % have 7 neutrons, called C-13 • Plants prefer C-12 • Scientists measure ratio in rocks, try to explain observations • Stable isotopes, not radioactive like C-14

  10. Features of the P-T carbon isotopic excursion • Ubiquitous – global, all kinds of rocks including limestone, paleosol nodules, kerogen, and vertebrate teeth! • Means that something big happened and that this can be used to find the boundary anywhere rocks deposited across the right time span are exposed • So fast and so extreme that it cannot be explained by volcanism or other “normal” processes

  11. www.kent.ac.uk/physical-sciences USGS

  12. Methane hydrate mechanism: • Enormous amounts of natural gas are stored in solid H2O (ice – but not quite the ice we are used to) cages at the bottom of the sea and under permafrost. This methane is enriched in C-12! • Methane is a powerful greenhouse gas so release of some would initiate warming, perhaps starting a positive feedback

  13. Proposed causes of dinosaur extinction • Out-competed by smarter, egg-eating mammals • Disease • Falling sea level • Volcanically driven climate change • Asteroid strike! (had been written off by 1980 because no crater had been found)

  14. www.physast.uga.edu/~jss/ 1980 - Walter and Luis Alvarez discover iridium rich clay layer www.geology.ucdavis.edu/~cowen/HistoryofLife/ktbits.gif

  15. http://www.lpl.arizona.edu/SIC/ Location of the Chicxulub crater - site of the K-T impact!

  16. Chicxulub - “tail of the devil” www.windows.ucar.edu/earth/images/chicxulb.gif

  17. Animation of Chicxulub crater formation

  18. Evidence for K-T impact • World-wide clay layer with iridium, shocked quartz, spherules, and carbon • 65 Ma tsunami deposits ringing the Caribbean • Chicxulub crater

  19. It was a BIG explosion! • Asteroid or comet was 10 km (6 mi) across • Moving at 75,000 km/hr (45,000 mi/hr) • 5 billion times the energy of Hiroshima • World-wide forest fires, tsunamis, acid-rain, year-long “nuclear winter” • At least 75% of all species went extinct, including 90% of all plankton • http://www.lpl.arizona.edu/impacteffects/

  20. Asteroid 1950-DA, March 16, 2880

  21. Unlike the K-T impact that killed the dinos, the cause of the P-T extinction is still the subject of vigorous debate!

  22. Tethys Sea Pangea X http://jan.ucc.nau.edu/~rcb7/ The blue planet, 260 Ma

  23. http://dsc.discovery.com Siberian Traps

  24. Proposed causes of P-T extinction: • Final assembly of Pangea – changes ocean currents, climate • Volcanism – Siberian traps flood basalt, Chinese explosive volcanism. Release CO2, causes warming, promotes ocean anoxia by weakening currents, lowering O2 solubility, and melting gas hydrates. • Impact • Combination

  25. Insert pic of AC • Petrified tree? • AC shot from above! With inset of teeth

  26. What fossils tell us about dinosaurs • How they looked - size, shape, skin • How they behaved - diet, locomotion, social life, as parents • Physiology - thermal regulation, growth patterns • History of life - speciation and extinction, relationships among groups • Environmental reconstruction, rock ages geochemistry, paleogeography, interaction between physical and biological worlds

  27. ← Griffin inspired by Protoceratops? ↓ web.ukonline.co.uk/conker/ www.dinoland.dk

  28. www.oum.ox.ac.uk/geolcoll.htm 1677 – Robert Plot publishes first known description of a dinosaur bone. However, he mistakes it for the femur of a giant human!

  29. www.lhl.lib.mo.us/events_exhib/exhibit/ex_paper_dino.shtml 1815 – William Buckland finds Megalosaurus jaw

  30. 1831 1830’s – Meet Meg, plus the happy water lizard home.uchicago.edu/~shburch/dinopaper.html 1833

  31. 1836 – Gideon Mantell discovers the teeth of Iguanodon www.lhl.lib.mo.us/events_exhib/exhibit/ex_paper_dino.shtml

  32. Iguanodon – notice the sprawling legs 1842 – Richard Owen defines the “Dinosauria”, which translates as “terrible lizards”

  33. Depiction by Owen circa 1850

  34. Benjamin Waterhouse Hawkins’ 1853 dinosaur reconstructions being prepared for display in the Crystal Palace, Hyde Park, London http://www.ric.edu/rpotter/cryspal.html

  35. www.simondevlin.com

  36. www.owen.k12.ky.us/trt/beverly/Megalosaurus_files/frame.htm

  37. http://www.healthstones.com/dinosaurdata/dinodata.html

  38. Nicholas Steno – “Father of stratigraphy” • Second half of the 1600’s • Said fossils were remains of organisms • Principle of Original Horizontality – rock layers laid down horizontally, any deviation from this due to later disturbance • Law of Superposition – lower layers are older, upper layers are more recent

  39. Early 1800’s geology comes alive! • 1795 – Theory of the Earth by James Hutton: how rock layers form, hot inside, old, uniformitarianism, natural selection • 1815 – Geologic map by William Smith: biostratigraphy • 1830-1833 – Principles of Geology by Charles Lyell: stratigraphy • 1859: On the Origin of Species by Darwin

  40. Archaeopteryx – London specimen, found 1861

  41. Taphonomy - the study of how fossils get preserved • How sedimentary rock deposits are formed and how dead animals get in them • Help us understand ancient ecosystems • Helps us understand biases in the fossil record • Some organisms and parts of organisms rarely preserved

  42. www.fossilhut.com Berlin specimen - 1877 www.sonoma.edu/users/g/geist/bio.html Solnhofen specimen - 60’s

  43. www.cmnh.org