Full Video |15:31

Full Video |15:31

Earth's history is too long for human timescales, so scientists use geological time. Earth's history is studied using fossils, and divided into four major eras: the Precambrian, the Paleozoic, the Mesozoic, and the Cenozoic.

©2005 Discovery Education| Grade(s) 6-8

Related Topics

  • absolute time
  • Age of Dinosaurs
  • amber
  • animal remains
  • birds
  • Cambrian
  • Cenozoic
  • deep time
  • dinosaur
  • dinosaur extinction
  • Earth

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