Saturday, January 22, 2005

The Great Dying

Some 250 million years ago, Earth was reduced to an almost lifeless planet -- a geologically active, but dead planet, with no remaining witnesses of its endless journey around the Sun. Paleontologists looking at the fossil record noticed some time ago that there is a gap in life's history on Earth. All signs of life just about vanished around 250 million years ago. For a brief moment in geologic time, the Permian-Triassic extinction, or the Great Dying, occurred.

This is not the same as the Cretaceous-Tertiary mass extinction that took out the dinosaurs around 65 million years ago. The Great Dying was different. 9 out of 10 marine species died. 7 out of 10 land species died. Plants, trees, microbes -- every class of life was impacted. It was like the planet itself was dying. It was slow -- it lasted millions of years. If we were there, we'd probably see the signs. The smart ones amongst us would be worried. Sadly, most people would have the same reactions they have today -- disbelief.

Researchers have recently published findings that points to a cause of the Great Dying. A combination of massive Siberian volcanic flows and a drop in ocean levels due to geologic activity lead to global warming and oxygen deprivation. Other scientists have also suggested that an asteroid impact, a nearby supernova or the formation of a super-continent may also have played a roll in, or caused the Great Dying.

For more information on this topic, consult the following links:
  • The Permian-Triassic Mass Extinction
  • Paleomap Project - see what the Earth looked like through geologic history.
  • A Modern Mass Extinction? - are we heading for the end of the world?
  • Rapid eruption of Siberian flood-volcanic rocks and evidence for coincidence with the Permian-Triassic boundry and mass extinction at 251 Ma [PDF]
  • New reptile material from the Lower Triassic of Madagascar: implications for the Permian-Triassic extinction event [PDF]
  • Changing Fluvial Environments in the Karoo Basin, South Africa, as a Result of the Permian/Triassic Extinction [PDF]

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