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Mesozoic Era

Mesozoic Era. Earth Science Chapter 23 Section 2. Mesozoic Paleogeography. Mass extinction of the Paleozoic Era provided opportunities for drastically different life forms The life forms filled empty niches Three Periods Triassic Jurassic Cretaceous. Breakup of Pangaea.

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Mesozoic Era

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  1. Mesozoic Era Earth Science Chapter 23 Section 2

  2. Mesozoic Paleogeography • Mass extinction of the Paleozoic Era provided opportunities for drastically different life forms • The life forms filled empty niches • Three Periods • Triassic • Jurassic • Cretaceous

  3. Breakup of Pangaea • Beginning of Era • Single global ocean • Single continent • Triassic Period • Pangaea begins to break apart • Heat beneath the continent caused it to expand • Brittle lithosphere began to crack • Cracks widened and continent began to split

  4. Sea Ways • Mid ocean rift systems developed • Seaways widened • Atlantic Ocean began forming • Triassic Period

  5. Changing Sea Level • Mid-Ocean Rift systems partly responsible for rise in sea level • Hot magma displaced seawater as new rock was formed • Dropped, however, at the end of the Triassic Period • Desert like conditions formed in Western North America • Sea level rose again in Jurassic Period • Continued to rise in Cretaceous Period

  6. Mountain Building • Collision of continents forced mountains upward

  7. CordilleraAn extensive chain of mountains • Occurred in Western Laurentia • Subduction of oceanic Farallon Plate beneath Laurentia’s western margin • Rocky Mountains • Sierra Nevada Mountains

  8. Cordilleran Orogeny • Phase One • Occurred during late Jurassic and early Cretaceous Periods

  9. Cordilleran Orogeny • Phase One: • Steep Slow Subduction • Phase Two: • Shallow faster subduction • Massive thrust faults • Phase Three • Very fast, very shallow subduction • Tectonic activity inland • Large vertical lifts

  10. Mesozoic Life • Phytoplankton • Microscopic organism at the base of the marine food chain • Abundant during Cretaceous

  11. Mesozoic Life • Plants • As temperatures warmed, plant life changes. • Tall cycad trees • Seed plants with true flowers • Ginkgoes • Pine trees • conifers

  12. Mesozoic Life • Terrestrial Animals • Mammals • Late Triassic • Same time as dinosaurs • Amniotic Eggs • Contain food and water required by developing embryo

  13. Mesozoic Life • Dinosaurs • Archosaurs • Unique skeletal structure • Speed and flexibility • Hip structure allows legs to be held underneath the body • (reptiles’ movement is more sprawling)

  14. Mass Extinction • Devastated terrestrial dinosaurs • Most marine reptiles • Plants • Today’s theory • Massive and volcanism and large meteorite (10 km diameter) impact caused climate problems • Occurred at end of Cretaceous • Caused long lasting greenhouse warming • Layer of clay from that time contains high amounts of iridium • Rare on Earth but common in asteroids

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