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The Mesozoic Era

The Mesozoic Era. When Dinosaurs Ruled the Earth. The Mesozoic Era. Began approximately 245 million years ago after a major mass extinction. Is subdivided into 3 periods: Triassic Jurassic Cretaceous Ends about 66 million years ago with a major mass extinction. Mesozoic Reptiles.

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The Mesozoic Era

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  1. The Mesozoic Era When Dinosaurs Ruled the Earth

  2. The Mesozoic Era • Began approximately 245 million years ago after a major mass extinction. • Is subdivided into 3 periods: • Triassic • Jurassic • Cretaceous • Ends about 66 million years ago with a major mass extinction

  3. Mesozoic Reptiles • Turtles • Crocodiles/Alligators • Lizards • Ichthyosaurs (large marine reptiles) • Pterosaurs (large flying reptiles) • Dinosaurs (land dinosaurs)

  4. Dinosaurs Myths • All dinosaurs are the same • Everything that is big and extinct is a dinosaur • All dinosaurs lived at the same time • All ‘dinosaurs’ are extinct… ...you’ll see!

  5. The Triassic Period245 - 206 million years ago • Immediately after the Permian Mass Extinction • Lots of new area is open for animals to live • Three general types of animals: • holdovers from before the extinction • new groups that lasted only a short time • new groups that lasted a long time

  6. The Triassic World

  7. Triassic Plant Life • Mosses • Scale Trees (like palm trees) • Ginkos (my favorite)

  8. Two Groups of Dinosaurs • Ornithischian • Hips were similar to modern bird hips • Carnivorous short-necked • Herbivorous, long-necked • Saurischian • Hips were similar to reptile hips • Herbivorous with grinding-teeth • Herbivorous without grinding-teeth

  9. Earliest Dinosaurs(Triassic) Pisanosaurus Length:3 feet Height:1 foot Weight:15 pounds Eoraptor: Length:3 feetHeight:1 feetWeight:20 pounds Lesothsaurus: Length:3 feet Height:1 foot Weight:15 pounds

  10. The Jurassic Period206 - 144 Million Years Ago • Giant plant-eating dinosaurs • Vicious carnivore dinosaurs • Oceans full of fish, squid, sharks, etc. • Ichthyosaurs and Plesiosaurs • Pterosaurs • Birds

  11. The Jurassic World

  12. Jurassic Plant Eating Dinosaurs • Many different forms • Many had ‘armor’ to protect themselves • Triceratops • Ankylosaurus • Many very large (larger than a Rhino/Hippo) • Some were extremely large (as long as a city block): Diplodocus Triceratops

  13. Ankyloasaurus Diplodocus

  14. Jurassic Carnivorous Dinosaurs • Many different forms • Some were very large: • Tyrannosaurus Rex • Allasaurus • Some were smaller: • Raptors, and many more • All had sharp teeth, claws, and speed

  15. Jurassic Marine Dinosaurs • Most with similar shapes as a dolphins or sharks • Ate fish and other marine animals • Some were VERY large • All could swim VERY fast Ichthyosaurus

  16. Jurassic Pterosaurs • Pterodactyls and Pterosaurs • Most had trouble ‘walking’ • Were very good flyers • Had hollow bones • Small (~ 1 foot) and very large (~ 16 feet)

  17. More Pterodactyls

  18. Jurassic Birds(?) - Archaeopteryx • Not a Pterosaur • Jaws and bone structure like dinosaurs • Bones are hollow, like birds • Feathers • Was this an evolutionary link between dinosaurs and birds?

  19. The Cretaceous Period144 - 66 million years ago • The last period when Dinosaurs lived • Ends with a mass extinction around 66 million years ago • First flowering plants!

  20. The Cretaceous World

  21. Cretaceous Plants • First plants with flowers • Their appearance was very rapid • They appeared at the same time as the number of insects increased… • Could insects have helped the flowering plants evolve?

  22. The Cretaceous Mass Extinction • Approximately 60% of all species went extinct. • Affected many land animals/plants • Affected fewer marine animals

  23. What organisms went extinct? • All dinosaurs • All pterosaurs • All ichthyosaurs • Many terrestrial plants • Many marine animals

  24. What organisms survived? • MAMMALS (!) • Birds • Many plants (ferns were the most successful plant for a while) • Trees with flowers • Small lizards/crocodiles/alligators/turtles • Fish, squids, sharks, etc.

  25. What caused the extinction? • Meteorite impact theory • 66 million years ago, a ~10 km wide meteorite struck the Earth near what is now Mexico.

  26. Meteorite Impact • This is an EXAGGERATED view of a meteorite impact

  27. How could a meteorite impact cause a mass extinction? • The impact caused shock waves, tidal waves, and sent a tremendous amount of dust into the atmosphere • As the dust re-entered the Earth’s atmosphere, it would have instantly heated the atmosphere causing tremendous forest fires • The dust could have caused the Earth’s climate to cool in the long-run by blocking sunlight • Plants, animals, etc went extinct due to the climate changes and competition between organisms

  28. Meteorite Impact Evidence #1 • Unique Quartz Crystals • Very commonly formed under high pressure/temperature • This quarts was only found in meteorite craters and nuclear testing sites

  29. Meteorite Impact Evidence #2 • Iridium • An element that is very rare in Earth rocks and very common in meteorites • The layer of rocks above the last dinosaur bones contains ~160 times ‘normal’ levels of iridium

  30. Problems with the Meteorite Impact Hypothesis • Why were some animals affected, while others were not? • Why did birds survive, and dinosaurs (a very close relative) not? • Why did small reptiles survive when small dinosaurs didn’t? • Why did mammals survive?

  31. Out-dated Hypotheses • Hay Fever - caused by flowering plants • Dinosaurs were so big, that they crushed themselves • Mammals out-competed the dinosaurs • Mammals ate all the dinosaur eggs • Cosmic rays killed the dinosaurs

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