Before history. Refers to the time before knowledge was recorded for use by future generations. Typically it refers to the era preceding the written word, though much knowledge was passed on orally before it was written. Anything dating from prehistory is said to be prehistoric. An example of prehistoric knowledge is the I Ching.

Much like prewater. Prewater is the stuff in which fish lived before there was water. Prehistory is what people lived in before history. History is, essentially, anything that has to do with civilization or its establishment. Prehistory is, then, the history of humanity prior to the development of culture based upon civilization. Since we all know civilization is the end-all to human invention and something upon which it is not possible to improve, prehistory isn't that important and the reality of prehistoric life is fairly irrelevant.

A brief prehistory of time:

15Bya - Universe Forms
4.6Bya - Solar system forms
4.5Bya - Earth's crust forms


3800MY: oldest rocks
800MY : 1st red algae
700 MY: 1st animals
500 MY: 1st land plants
350 MY: 1st reptiles
200 MY: 1st dinosaurs


Precambrian Era, 4550 - 550MY
Paleozoic Era (570MY-251MY)
Periods in Paleozoic:
 Cambrian, 550-505MY - first jawless fishes
 Ordovician, 505-438MY - more jawless fishes
 Silurian, 438-408MY - 1st ray finned/lobed fish
 Devonian, 408-360MY - fish dominant, 1st amphibians
 Carboniferous, 360-286MY - amphibians and fish
    - Mississippian period, 360-322MY
    - Pennsylvanian period, 322-286MY
 Permian 286-248MY - amphibians dominant, 1st mammal-like reptiles, pangaea forms

Extinction Event 251MY - all trilobites extinct

Mesozoic Era (251MY-65MY) - "Age of reptiles"
Periods in Mesozoic:
 Triassic, 251-225MY - reptiles, 1st dinosaurs
 Jurassic, 213-144MY - dinosaurs dominant, first mammals, birds
 Cretaceous, 144-65MY - dinosaurs dominant, small mammals, birds, T. Rex 75MY

Extinction Event 65MY - K-T extinction kills dinosaurs

Cenozoic Era (65MY-present) - "Age of mammals"
Periods in Cenozoic:
  Tertiary, 65-2MY
  Epochs in Tertiary:
    Paleocene, 65-54MY
    Eocene, 54-38MY
    Oligocene, 38-26MY
    Miocene, 26-7MY
    Pliocene, 7-2MY
 Quaternary, 2MY-present
  Epochs in Quaternary:
    Pleistocene, 2MY-10000Y
    Holocene, 10000Y-present

Extinction Event - Current day

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