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1, Harvey and Mazeski, History of Earth Timeline

  • Sun formed.

    Sun formed.
    Our solar system was a swirling mass of gas and dust. Over time, most of this material was pulled together by gravity and formed the sun. Scientists believe that the plants formed through repeated collisions of the leftover space debris.
  • Earth formed.

    Earth formed.
    Earth grew larger as gravity pulled in more debris. The collisions between Earth and space debris also released a great deal of thermal energy.
  • Organic molecules accumulate.

    Organic molecules accumulate.
    Scientists infer that organic molecules began to accumulate.
  • First cellular life.

    First cellular life.
    Archaea are thought to be similar to the types of cellular life that first populated Earth about 4 billion years ago.
  • Prokaryotes begin to photosynthesize.

    Prokaryotes begin to photosynthesize.
    Unicellular prokaryotes called lynbgya grew in colonies and formed layered structures called stromatolites.
  • Life becomes photosynthetic.

    Life becomes photosynthetic.
  • Earth looks the same.

    Earth looks the same.
    By this time, Earth probably appeared much as it does today.
  • O2 levels reached today’s levels

    O2 levels reached today’s levels
    O2 levels reached today’s levels.
  • Eukaryotes are formed.

    Eukaryotes are formed.
    A type of small aerobic prokaryote was "eaten" by a larger anaerobic prokaryote. The smaller prokaryote began to live and reproduce inside of the larger prokaryote. This theory is called endosymbiosis.
  • Ozone (O3) formed.

    Ozone (O3) formed.
    Ozone (O3) formed – protected organisms from harmful UV rays so they could exist on land
  • Redi

  • Spallanzani

  • Pasteur

  • Oparian and Haldane

     Oparian and Haldane
  • Cech

  • Urey and Miller

    Urey and Miller
    -tested Oparian’s hypothesis
    -they were successful
  • Fox

    -did research on physical structures that may have led to the first cells
  • Margulis

    -proposed that early prokaryotes may have developed a mutual beneficial relationship