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Chemistry LibreTexts

Mass Extinctions

  • Page ID
    185403
  • 65 million years ago, 60 to 80% of all life on this planet died. This is not the first time Earth has experienced mass extinctions. The fossil record shows a pattern of extinctions occurring roughly ever 26 million years. Scientists tend to agree that there have been 5 or 6 mass extinctions.

    What could account for these mass extinctions? The list of suggested explanations is long, but most include

    • geologic events (volcanoes)
    • cosmic events (asteroids or comets)
    • climatic events (hot versus cold)
    • pathogenic events (diseases)


    Currently the majority of evidence supports the idea that the Earth was struck by a large meteor 10-20km in diameter forming the Chicxulub Crater on the Yucatan peninsula in Mexico. Some scientists disagree and suggest that massive volcanic eruptions could have precipitated the catastrophe.

    From http://education.gsfc.nasa.gov/

     

    Think Questions

    1. Is there a pattern to when the mass extinctions occur?


    Phanerozoic_Biodiversity_5733922a7e12a.png

    Image credit: https://commons.wikimedia.org

     

    2. Could we be in a mass extinction event now?