Review of Earth’s Eras
Precambrian 88% of Earth’s history. Earth starts as a liquid. Heavy material settles to core. Light material rises to crust. As crust hardens, plants evolve. (Algae) First oxygen around 3.5 BYA.
Paleozoic (Old Life) 540 MYA = Free oxygen in atmosphere. Earth cools to habitable temp. 3 main parts: Age of Invertebrates (no backbone) Age of Fishes Age of Amphibians
Mesozoic (Middle Life) Age of Reptiles. Dinosaurs. First Flowering Plants. First Birds. Pangaea Breaks apart.
Cenozoic (New Life) Kainos-zoic. Greek Many dinosaurs extinct. 7 Continents. Age of Mammals Hair. Warm Blooded. (always same temp) Breathe Air. (lungs not gills) Live Birth. (no eggs) Mothers nurse young.