History of Life

    As you may know, all life on the earth started out with one-celled micro-organisms, and has now progressed to intelligent human beings. This process is called evolution. (The Darwin/Wallace theory explains why evolution occurs.)  If you have a canyon wall of sedimentary rock like the Grand Canyon, you can look at the fossils found on the top to bottom like a calendar that shows the diversity of life.

    The history of the earth is divided into four sections:

   Precambrian era:

• 4.6 billion years to 570 million years ago
• Formation of the earth
• First bacteria
• First soft bodied animals

    Summary:

• Few fossils discovered in the sedimentary rock of this era

    Paleozoic Era:

• 570 million years to 225 million years ago
• Millions of trilobites, shellfish and coral
• First fish with jaws
• First large land plants
• First insects
• New varieties of fish
• First amphibians
• First reptiles

    Summary:

• Animal fossils range from one-celled organisms (sponges, Celia, amoebas, etc.) to those living in water/on land (amphibians)
• Plant fossils such as ferns and mosses appear

    Mesozoic Era

• 225 million years to 65 million years ago
• First birds and mammals 
• First flowering plants
• Dinosaur populace explodes
• Dinosaurs die off

    Summary:

• Gigantic reptile and dinosaur fossils are extremely common.

    Cenozoic Era

• 65 million years to present
• New varieties of flowering plants
• New varieties of mammals
• First human-like fossils

    Summary:

• Familiar animals like the mammoth, cyber-tooth tiger, and Neanderthals are fossilized.
• Fossils bear evidence of the past ice age.

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