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Period 2 Mahajan, Fanning, History of Earth Timeline

  • (5 BYA) Solar system begins to form

    (5 BYA) Solar system begins to form
    A cloud of dust and gas was disturbed from a possible nearby Supernova. The explosion caused space waves which squeezed the gas and dust together, forming many smaller planets which collided into one another to form bigger planets.
  • (4.6 BYA) Earth begins to Form.

    (4.6 BYA) Earth begins to Form.
    Planet Earth begins to form when the nearby debris, or smaller planets, begin to collide.
  • (4 BYA) Formation of Earth's Atmosphere

    (4 BYA) Formation of Earth's Atmosphere
    Volcanic activity released the first atmospheric gases on Earth. These elements included Helium and Hydrogen, the lightest gases. Later on Nitrogen and other gases were added
  • (4 BYA) First Life Forms on Earth

    (4 BYA) First  Life Forms on Earth
    Archae-like organisms are found to be Earth's first life. These organisms were chemosythetic, meaning they obtain energy through chemical reactions.
  • (3.5 BYA) Origin of Stromatolites

    (3.5 BYA) Origin of Stromatolites
    The oldest stromatolites, a type of cyanobacteria, are believed to originate. These organisms obtain energy through photosynthesis, and show signs of the first aerobic respiration.
  • (3 BYA) Photosynthetic Life Originates

    (3 BYA) Photosynthetic Life Originates
    After the finding of the aerobic Stromatolites 500 million years before, photosynthetic life is commonly found now. These organisms include many forms of Prokaryotic Bacteria.
  • (2.2 BYA) Earth Develops

    (2.2 BYA) Earth Develops
    More than two billion years after it began to form, Earth reaches a state similar to what it looks like today. It no longer collided with any smaller planets to grow.
  • (2 BYA) Oxygen Levels reached Today's Levels

    (2 BYA) Oxygen Levels reached Today's Levels
    The composition of Earth's atmosphere is compiled of a nearly identical amount of oxygen compared to that of todays.
  • (1.5 BYA) The First Eukaryotes

    (1.5 BYA)  The First Eukaryotes
    Small aerobic prokaryotes reproduced inside a larger, anaerobic prokaryote. This is known as endosymbiosis, or the making of the first eukaryotic organism.
  • ( 1 BYA) Ozone is formed

    Ozone formed when oxygen molecules collided with sunlight, which split some oxygen molecules into O, while othrs remained O2. These single and double oxygens then combined to form ozone. Ozone is poisonous to plants and animals, but helpful in controlling UV rays.
  • (1665) First Microscopes

    (1665) First Microscopes
    The light microscope was used by Robert Hooke to study cell like units inside of cork. These later started the idea of organisms having cells.
  • (1668) Redi's Experiment

    (1668) Redi's Experiment
    Francesco Redi tested the formation of maggots on rotten meat. He did this by covering one sample so flies couldn't get to it, while leaving another sample out in the open. He found that the covered sample didn't have maggots since the flies couldn't get to it. This supported biogenesis.
  • (Mid 1700s) Spallanzani's Experiment

    (Mid 1700s) Spallanzani's Experiment
    Similar to Redi, Spallanzani tested the concept of spontaneous generation on microorganisms. He did this by boiling broth. One flask was covered after being boiled, (to avoid air exposure), while the other flask remained open. It was found that the open flask became cloudy, which meant organisms were inside. He concluded that microorganisms couldn't reproduce in boiled, closed broth.
  • (Mid 1800s) Pasteur's Experiment

    (Mid 1800s) Pasteur's Experiment
    Pasteur took Spallanzani's concept and retested it using a curve-neck flask instead of a closed flask. He then took of the neck and found that the broth became cloudy. So, when the flask had a curved neck, no microorganisms could get in. This supported biogenesis.
  • (1905) Radiometric Dating

    (1905) Radiometric Dating
    Radiometric dating provided a new way for scientists to find the age of various organic/inorganic objects. It involves using isotopes of various elements to determine the age of the given sample.
  • (Early 1900s) Oparin's Hypothesis

    (Early 1900s) Oparin's Hypothesis
    Oparin hypothesized how organic compounds may have developed. He thought that at high temperatures, gases may form simple organic compounds like amino acids.
  • (Early 1900s) Fox

    (Early 1900s) Fox
    Studied early cell-like organisms (microspheres and coacervates). This gave us an idea on how the first cells may have evolved
  • (1953) Urey and MIller

    (1953) Urey and MIller
    Experimented using Oparin's hypothesis. They tested various gases being charged with electricity, and they ended up producing organic compounds!
  • (1960s) Lynn Margulis

    (1960s) Lynn Margulis
    Hypothesized that cellular organelles were a result of endosymbiosis. She found that the organelles were indeed similar to early bacteria.
  • (1980s) Thomas Cech

    (1980s) Thomas Cech
    Coined and discovered the term ribozyme. This is a type of RNA that aided in being a catalyst. This produced evidence of self-replicating molecules of RNA.