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Mike Kozina SASS July 18, 2012

Dino Science. Mike Kozina SASS July 18, 2012. What is a dinosaur?. That’s right—birds are now dinosaurs!. Types of Dinosaurs. Saurischia : Lizard-Hipped. Ornithischia : Bird-Hipped. Thyreophorans. Sauropods. Theropods. Ornithopods. Marginocephalia. NBA Players. Dino Sizes.

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Mike Kozina SASS July 18, 2012

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  1. Dino Science Mike Kozina SASS July 18, 2012

  2. What is a dinosaur?

  3. That’s right—birds are now dinosaurs!

  4. Types of Dinosaurs Saurischia: Lizard-Hipped Ornithischia: Bird-Hipped Thyreophorans Sauropods Theropods Ornithopods Marginocephalia NBA Players

  5. Dino Sizes

  6. Dino Sizes

  7. When did Dinosaurs rule the earth?

  8. Dinosaur Motion/Mechanics How fast did dinosaurs go? How could they support such large bodies? Did land dinosaurs swim?

  9. Similarity E.g.: Animal mass ~ bone volume; Bone strength ~ bone cross section can’t just scale up • Simple scaling does not necessarily reproduce the same results

  10. So, how can we relate big to small? Unitless ratio of relevant physical parameters: • g = acceleration from gravity • v = velocity • L = linear length scale Froude Number (centripetal force/gravitational force):

  11. Other similarity terms you may have heard Reynold’s number (inertial forces/viscous forces) Strouhal number (oscillation time/characteristic translation time) Prandtl number (viscous diffusion rate / thermal diffusion rate)

  12. How fast could they run, and how do we know? Estimate speed of dinosaurs using: Stride length (from footprints) Hip height Froude number for modern day mammals So, how fast? Sauropods ~ 1m/s Fastest tracks (from horse-sized biped) ~12m/s Problems: Even for mammals scaling fails for small sizes because movement pattern very different Footprints only tell velocity in certain types of terrain (those likely to have tracks saved)—not representative

  13. Other ways to estimate velocity • Relate bone strength to general athleticism • E.g. Triceratops estimated to be in between elephant and rhino in speed • Computer simulations: • Genetic algorithms search to extremize parameters such as energy consumption or speed • Some require knowing motion patterns Can use constraints to eliminate impossible orientations

  14. Some simulation results

  15. Size Problems: How could Littlefoot grow so big?

  16. What about blood flow? Open question Extremely robust hearts? Possibility that long necks never raised above ~30degrees?

  17. Did dinosaurs swim?

  18. Why did they die out? • Hormonal problems leading to thin eggshells • Volcanos put dust in the air blocking the sun • Over predation by carnosaurs • Slipped disks in vertebral column • Blindness from cataracts • Climate became • Too hot • Too cold • Too wet • Too dry • Constipation • Fluctuations in the gravitational constant, somehow affecting dinosaurs • Radiation from a supernova • Uranium poisoning

  19. Really, why did they die out? Overwhelming evidence for asteroid colliding with the earth Sharp break in fossil type—K/T boundary High levels of iridium in soil Large crater in Chixhulub, Mexico 65.5 MYA Estimate size of asteriod ~10km diameter (since iridium at K/T found worldwide)

  20. More evidence for asteroid impact Shocked quartz caused by impact Microtektites—bits of glass ejected from impact site

  21. Dino-related Research at SLAC Use synchrotron to pick out different chemicals left in Archaeopteryx fossil Can link chemicals to pigment density

  22. Selected Bibliography • Dinosaur Diversity • Wang, PNAS103 13601-13605 (2006) • Dinosaur Biomechanics/Motion • Sellers, Proc. R. Soc. B 274 2711-2716 (2007) • Alexander, Scientific American, April 1991 • Alexander, Proc. R. Soc. B 273 1849-1855 (2006) • Sauropod Size Issues • Seymour, Biol. Lett. 5 317-319 (2009) • Sander, Science322 200-201 (2008) • Henderson Proc. R. Soc. Lond. B (Suppl.)271 S180-S183 (2004) • General Dino Stuff (includes all info I used about extinction) • Fastovsky, D. and Weishampel, D. Dinosaurs: A Concise Natural History. Cambridge University Press (2009) • Dino research at SLAC • Bergmann, PNAS 107 9060-9065 (2010) • Similarity in other contexts (non-dino) • Landau, L.D. and Lifshitz, E.M. Fluid Mechanics: Course of Theoretical Physics Vol. 6. 2nd Ed. Butterworth-Heinemann (2010) • http://en.wikipedia.org/wiki/Dimensionless_number

  23. Thanks for listening!

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