dino science

Mike Kozina

SASS

July 18, 2012 1

Dino Science

What is a dinosaur?

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That’s right—birds are now dinosaurs!

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Types of Dinosaurs

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Sauropods

Theropods

Marginocephalia

Saurischia: Lizard-Hipped Ornithischia: Bird-Hipped

NBA Players

Thyreophorans

Ornithopods

Dino Sizes

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Name Height Length Weight Ankylosaurus (armored lizard) 7 ft. 2.1 m 35 ft. 10.6 m 10,000lbs 4,536kg. Apatosaurus (deceptive lizard) 15 ft. 4.5 m 75 ft. 22.9 m 66,000lbs 29,937kg. Argentinosaurus (Argentina lizard) 70 ft. 21.4 m 120 ft. 36.6 m 220,000lbs 99,792kg Brachiosaurus (arm lizard) 50 ft. 15.2 m 100 ft. 30.5 m 100,000lbs 45,360kg Compsognathus (elegant jaw) 2 ft. 0.6 m 3 ft. 0.9 m 8lbs 3.6kg Corythosaurus (helmet lizard) 16 ft. 4.9 m 30 ft. 9.1 m 8,860lbs 4,019kg Deinonychus (terrible claw) 5 ft. 1.5 m 9 ft. 2.7 m 175lbs 80kg Iguanodon (iguana tooth) 18 ft. 5.5 m 30 ft. 9.1 m 10,000lbs 4,536kg Seismosaurus (tremor lizard) 84 ft. 25.6 m 150 ft. 45.7 m 200,000lbs 90,720kg Stegosaurus (plated lizard) 11 ft. 3.4 m 30 ft. 9.1 m 6,000lbs 2,722kg Triceratops (three-horned face) 9.5 ft. 2.9 m 26 ft. 7.9 m 14,000lbs 6,350kg Tyrannosaurus (tyrant lizard) 23 ft. 7.0 m 50 ft. 15.2 m 14,000lbs .6,350kg Velociraptor (swift robber) 2 ft. 0.6 m 6 ft. 1.8 m 250lbs .113kg

Dino Sizes

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Name Height Length Weight Ankylosaurus (armored lizard) 7 ft. 2.1 m 35 ft. 10.6 m 10,000lbs 4,536kg. Apatosaurus (deceptive lizard) 15 ft. 4.5 m 75 ft. 22.9 m 66,000lbs 29,937kg. Argentinosaurus (Argentina lizard) 70 ft. 21.4 m 120 ft. 36.6 m 220,000lbs 99,792kg Brachiosaurus (arm lizard) 50 ft. 15.2 m 100 ft. 30.5 m 100,000lbs 45,360kg Compsognathus (elegant jaw) 2 ft. 0.6 m 3 ft. 0.9 m 8lbs 3.6kg Corythosaurus (helmet lizard) 16 ft. 4.9 m 30 ft. 9.1 m 8,860lbs 4,019kg Deinonychus (terrible claw) 5 ft. 1.5 m 9 ft. 2.7 m 175lbs 80kg Iguanodon (iguana tooth) 18 ft. 5.5 m 30 ft. 9.1 m 10,000lbs 4,536kg Seismosaurus (tremor lizard) 84 ft. 25.6 m 150 ft. 45.7 m 200,000lbs 90,720kg Stegosaurus (plated lizard) 11 ft. 3.4 m 30 ft. 9.1 m 6,000lbs 2,722kg Triceratops (three-horned face) 9.5 ft. 2.9 m 26 ft. 7.9 m 14,000lbs 6,350kg Tyrannosaurus (tyrant lizard) 23 ft. 7.0 m 50 ft. 15.2 m 14,000lbs .6,350kg Velociraptor (swift robber) 2 ft. 0.6 m 6 ft. 1.8 m 250lbs .113kg

When did Dinosaurs rule the earth?

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Dinosaur Motion/Mechanics • How fast did dinosaurs go?

• How could they support such large bodies?

• Did land dinosaurs swim?

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Similarity • Simple scaling does not necessarily reproduce

the same results

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E.g.: Animal mass ~ bone volume; Bone strength ~ bone cross section can’t just scale up

So, how can we relate big to small?

Unitless ratio of relevant physical parameters:

1. g = acceleration from gravity

2. v = velocity

3. L = linear length scale

Froude Number (centripetal force/gravitational force):

𝐹 =𝑣2

𝑔𝐿

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Other similarity terms you may have heard

• Reynold’s number (inertial forces/viscous

forces) 𝑅 =𝜌𝑣𝐿

𝜂

• Strouhal number (oscillation

time/characteristic translation time) 𝑆 =𝑣𝜏

𝐿

• Prandtl number (viscous diffusion rate /

thermal diffusion rate) 𝑃 =𝜂𝐶𝑝

𝑘

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Estimate speed of dinosaurs using: 1. Stride length (from footprints) 2. Hip height 3. Froude number for modern day

mammals So, how fast? 1. Sauropods ~ 1m/s 2. Fastest tracks (from horse-sized

biped) ~12m/s Problems: 1. Even for mammals scaling fails

for small sizes because movement pattern very different

2. Footprints only tell velocity in certain types of terrain (those likely to have tracks saved)—not representative

How fast could they run, and how do we know?

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

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Some simulation results

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Size Problems: How could Littlefoot grow so big?

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What about blood flow?

• Open question

• Extremely robust hearts?

• Possibility that long necks never raised above ~30degrees? 16

Did dinosaurs swim?

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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 1. Too hot

2. Too cold

3. Too wet

4. Too dry

• Constipation

• Fluctuations in the gravitational constant, somehow affecting dinosaurs

• Radiation from a supernova

• Uranium poisoning

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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)

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More evidence for asteroid impact • Shocked quartz

caused by impact

• Microtektites—bits of glass ejected from impact site

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Dino-related Research at SLAC

• Use synchrotron to pick out different chemicals left in Archaeopteryx fossil

• Can link chemicals to pigment density 21

Selected Bibliography • Dinosaur Diversity

– Wang, PNAS 103 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, Science 322 200-201 (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

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Thanks for listening!