Dinosaur Evolution

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Dinosaur Evolution
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How do we know when dinosaurs lived?

• Layers of sedimentary rock absolute dating
• Late Triassic (during Mesozoic) through end of
  the Cretaceous
• Also see birds flowers for the first time
  during the Mesozoic (you know this!)

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Dinosaurs?

• Terrible Lizards (1841)
• Sir Richard Owen
• Not all reptiles are dinosaurs!
• Dinosaurs did not fly or swim!
• Pterodactyls were flying lizards (or at least
  winged lizards)

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Ornithischia

• 1887- bird hipped (posterior pubis along ischium)

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• Ceratopsia (Triceratops), Thyreophora
  (Stegosaurus), Ornithopoda (Iguanodon,
  Hadrosaurs)
• Some may have been bipedal

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Saurischia

• Lizard pelvis
• Pubis anterior downward

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• Up to 75,000 kg
• (over 165,000 lbs!)
• Brachiosaurus probably had a blood pressure that
  exceeded 630mmHg (yours is probably around
  120mmHg)

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• Sauropoda- herbivores(Diplodocus )
• Therapoda (bipedal meat eaters) T. rex,
  Maniraptora (Velociraptor), Dilophasaurus

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Good bye

• Cretaceous-Tertiary Extinction (K/T Extinction)
• Active plate movement, mountain-building,
  volcanism
• Lowering of global sea level
• Gentle global cooling
• Asteroid impact

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K/T Extinction

• Chicxulub (devils tail) crater- Gulf of Mexico
• Block sunlight
• Short-term global warming
• Global wildfires
• Acid rain
• Long term global cooling

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