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What caused Earth’s first mass extinction?

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  • Published
    16th Nov, 2021


A recently published paper has come up with a ‘new reason’ behind the first mass extinction, also known as the Late Ordovician mass extinction.


What’s the new finding?

  • The article notes that the cooling climate likely changed the ocean circulation pattern.
  • This caused a disruption in the flow of oxygen-rich water from the shallow seas to deeper oceans, leading to a mass extinction of marine creatures.

What is mass extinction?

  • Mass extinctions are defined as any substantial increase in the amount of extinction (lineage termination) suffered by more than one geographically wide-spread higher taxon during a relatively short interval of geologic time, resulting in an at least temporary decline in their standing diversity.

Major mass extinction events in the geological history of Earth:

  • Ordovician-Silurian extinction 485 to 444 million years ago: killed about 85% of all species. 
  • Late Devonian extinction - 383-359 million years ago: wiped out about 75% of the world’s species.
  • Permian-Triassic extinction - 252 million years ago: also known as the Great Dying caused the extinction of over 95% of all species.
  • Triassic-Jurassic extinction - 201 million years ago: eliminated about 80% of Earth’s species, including some dinosaurs.
  • Cretaceous-Paleogene extinction - 66 million years ago

What’s leading to the extinction?

  • destruction and fragmentation of habitats
  • direct exploitation like fishing and hunting
  • chemical pollution
  • invasive species
  • human-caused global warming
  • Uncontrolled human population
  • Overexploitation of resources

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