CAMBRIAN PERIOD (570 million years ago to 505 million years ago)

ORDOVICIAN PERIOD  (505 million years ago to 438 million years ago)

       438    Taconic Orogeny (first of three mountain building episodes in North America

 SILURIAN PERIOD  (438 million years ago to 408 million years ago)

    ~425    First land plants

      420    Fish developed teeth and jaws

DEVONIAN PERIOD  (408 million years ago to 360 million years ago)

     375   First amphibians

     360   Acadian Orogeny (second micro-continent impact causes new mountain range)

  MISSISSIPPIAN PERIOD  (360 million years ago to 320 million years ago)


PENNSYLVANIAN PERIOD  (320 million years ago to 280 million years ago)

                Extensive "coal swamps"

    ~310   First reptiles

      240   Alleghenian Orogeny (African plate impacts North America, causing Allegheny Mountains)

PERMIAN PERIOD  (280 million years ago to 225 million years ago)


TRIASSIC PERIOD  (225 million years ago to 190 million years ago)

The first turtles, crocodiles, dinosaurs, sea reptiles, flying reptiles, and mammals appear.

    ~225    First modern bony fish

    ~210    Pangea breaks up

JURASSIC PERIOD  (190 million years ago to 135 million years ago)

The first birds appear.  Dinosaurs reach their greatest size. Insects were plentiful.  Ammonites flourish in the sea.  Mammals begin.

    ~190    First birds

CRETACEOUS PERIOD  (135 million years ago to 65 million years ago)

Horned and armored dinosaurs become common.  Flowering plants develop.  Mammals expand.

    130    Monotremes diverge from mammal lineage

  130     Pangaea begins to split  

    120    Marsupials and Placentals diverge in mammal lineage

  100-75 Marsupials expand from N. America to S. Amer.(Gondwana)  


TERTIARY PERIOD  (65 million years ago to 3 million years ago)

    65         PALEOCENE  EPOCH (Mammals expand rapidly)

    60         First rodents and lagomorphs

  55-35   Creodonts (placentals) dominate in N. America

  55-35  "Wolf-sheep" turn into whales

  55        Cat & Dog carnivores split (Cats in Asia; Dogs in North America)  

    53        EOCENE EPOCH (First camels, horses, and other mammals appear)

  50        Crocs attempt to dominate, but lose to mammals

  40        Antarctica ices over  (marsupials become extinct in Antarctica)

    36        OLIGOCENE EPOCH (Grasslands spread, primitive apes appear)

    30        MIOCENE EPOCH (Mammals reach their greatest diversity)

  30        Earth’s rotational shift moves N. America closer to the North Pole.  Weather changes from wet and warm to cold and dry (from tropical to temperate)              

  30        Bering Strait land bridge opens; true Cats & Dogs in N. America

  30        Carnivores dominate over creodonts in N. America

  25        Marsupials die out in N. America, but have developed into pouched killers dominating South America for 30 million years

  25,15,5 Hot maximums  

    8        PLIOCENE EPOCH (Human beings appeared)

  5-6      Sabre-toothed caranivore designs flourish

  5          Raccoon drifts to S. America, dominates as bear-like raccoon

  4          "Thunderbirds" dominate over S. American marsupials

  4          Cooler, drier leads to savannas, ungulates, and pantherines

  3          N. & S. America join; placental canivores wipeout marsupial carnivores  

QUATERNARY PERIOD  (3 million years ago to present)

    2         PLEISTOCENE EPOCH (Modern human beings develop.  Ice Age begins)

  0.01    HOLOCENE EPOCH (10,000 years ago to present)