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Life’s Timeline

Life’s Timeline. Earth is Born. aka The Precambrian Era. The First 100 million years. Cosmic junk hits Giant collisions melt the planet Density stratification. Hydrogen cyanide Carbon Dioxide Carbon Monoxide Nitrogen Hydrogen Sulfite Water. TOXIC!!!. The First Atmosphere.

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Life’s Timeline

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  1. Life’s Timeline

  2. Earth is Born aka The Precambrian Era

  3. The First 100 million years • Cosmic junk hits • Giant collisions melt the planet • Density stratification

  4. Hydrogen cyanide Carbon Dioxide Carbon Monoxide Nitrogen Hydrogen Sulfite Water TOXIC!!! The First Atmosphere

  5. 4 b.y.a. • 1st solid rocks • Lots of volcanos • Cosmic junk bombards surface • Too hot for liquid H2O!

  6. 3.8 b.y.a. • Cool enough for liquid water • Storms cover Earth in water • Oceans form • Lots of dissolved iron in oceans

  7. 3.6 – 3.5 b.y.a. • Bacteria-like life forms common in oceans • Evidence: microfossils!

  8. 2.2 b.y.a. • Photosynthetic bacteria producing Oxygen • Oxygen + Iron in oceans = RUST appears! • Rust falls to ocean floor = oceans turnblue-green • Oxygen builds up in atmosphere…

  9. Atmospheric O2 Accumulates • Ozone forms protective layer! • Sky turns blue! • Cells DIE OR MOVE to oxygen-free habitats (Their descendants are still there!) • New cells use oxygen!

  10. 2 b.y.o • Prokaryotic cells evolve interior membranes e.g. nuclei!!! • Endosymbiosis leads to Eukaryotic cells with • Mitochondria • chloroplasts

  11. Later… • Eukaryotic cells continue to evolve Sexual Reproduction!!! • Evolution SPEEDS UP!!!, as sexual reproduction allows allele shuffling so that offspring are not identical to their parents.

  12. A few hundred-million years later… • Evolution of MULTICELLULAR ORGANISMS!!!

  13. Earth as a Toddler The Paleozoic Era

  14. The Cambrian Period: 544-505 m.y.a. • Diversification • Firsts: • Tough body parts (outer skeletons, shells) • Animals • Invertebrates: jelly fish, worm, sponge • Brachiopods: (2 shells) Trilobites

  15. The Ordovician and Silurian Periods:505-410 m.y.a. • Firsts: • Backbones!!! first vertebrates: jawless fishes • Insects! (invertebrates) • Land Plants! (low to ground in damp areas)

  16. The Devonian Period:410-363 m.y.a. • Ferns and dry-land plants • SHARKS!!! • jaws, bones, and scales • LAND ANIMALS! • 1st AMPHIBIANS!!!

  17. The Carboniferous and Permian Periods:363-245 m.y.a. • REPTILES!!! • Huge Winged Insects! • Vast Forests! (giant ferns)

  18. The PermianMASS EXTINCTION:End of the Paleozoic • Extinct: • 95% of ocean life • Many amphibians, land animals and plants • Survivors: some fish and reptiles…

  19. The Mesozoic Era Age of the Reptiles

  20. The Triassic Period:245-208 m.y.a. • Mass Extinction of • fishes, insects, reptiles, cone-bearing plants • DINOSAURS!!! (225 m.y.a.) • MAMMALS! (late Triassic) • Evolved from reptiles • Very small

  21. The Jurassic Period:208-145 m.y.a. • Dominant Players: Dinosaurs (on land) • BIRDS!!! • Archaeopteryx • Evolved from dinosaurs

  22. The Cretaceous Period:145-65 m.y.a. • Land: Dinosaurs (T. rex) • Air: Birds, Flying Dinosaurs • Water: Turtles, Crocodiles, Dinosaurs, Fish, Invertebrates • Firsts: • Leafy Trees, FLOWERS!!! (fruits)

  23. The MesozoicMASS EXTINCTION • Over 50% of all plants and animals • All Dinosaurs

  24. The Cenozoic Era The Age of Mammals

  25. The Tertiary Period:65-1.8 m.y.a. • Warm, mild climate • Whales, Dolphins • Grazing mammals • The earliest Human Ancestor (3.5 m.y.a.)

  26. The Quaternary Period:1.8 m.y.a. - Present • ICE AGES • oceans falls 100m • 20 k.y.a. – warms up – oceans rise again • Firsts: HUMANS (~150 k.y.a.)

  27. Life’s Timeline

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