Historical Geology.

  • Cambrian Period. - 570 to 500 MYA.

    Cambrian Period. - 570 to 500 MYA.
    Earliest record of marine life. Triobites are dominant.
  • Ordovician Period. - 500 to 435 MYA.

    Ordovician Period. - 500 to 435 MYA.
    Echinoderms. (Starfish, sand dollars, sea urchin, and sea cucumbers.) Invertabrates are dominant, mollusks become abundant. Earliest fish are jawless and later armored fished and later jawed.
  • Silurian Period. - 435 to 335 MYA.

    Silurian Period. - 435 to 335 MYA.
    Earliest terrestrial plants and animals. Eurypterids develope.
  • Devonian Period. - 395 to 345 MYA.

    Devonian Period. - 395 to 345 MYA.
    Armored fish go extinct but abundance of several species of fish. Earliest amphibians and ammonties.
  • Carboniferous Period. - 345 to 280 MYA.

    Carboniferous Period. - 345 to 280 MYA.
    Abundant sharks and amphibians. Large swamps and coal forming forests. Earliest reptiles, scale trees, and seed ferns.
  • Permian Period. - 280 to 225 MYA.

    Permian Period. - 280 to 225 MYA.
    Extinction of many types of marine animals including trilobetes.
  • Triassic Period. - 225 to 195 MYA.

    Triassic Period. - 225 to 195 MYA.
    Earliest dinosaurs, adundant cycods, confiers.
  • Jurassic Period. - 195 to 136 MYA.

    Jurassic Period. - 195 to 136 MYA.
    Earliest birds and mammals abundant. Dinosaurs and ammonites.
  • Cretaceous Period. - 136 to 65 MYA.

    Cretaceous Period. - 136 to 65 MYA.
    Age of reptiles. Earliest flowering plants. Climax of dinosaurs followed by their extinction. Great decline of brachiopods. Abundance of fish.
  • Tertiary Period. - 65 to 1.8 MYA.

    Tertiary Period. - 65 to 1.8 MYA.
    Earliest placental mammals, modern mammals, large running mammals.
  • Quaternary Period. - 1.8 tp present MYA.

    Quaternary Period. - 1.8 tp present MYA.
    Large carnivores, neanderthais, humans, and masidons.