Cambrian–Ordovician extinction event

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The Cambrian–Ordovician extinction event occurred approximately 488 million years ago (m.y.a.). This early Phanerozoic Eon extinction event eliminated many brachiopods and conodonts, and severely reduced the number of trilobite species.

It was preceded by the less-documented (but probably worse) End Botomian extinction event around 517 m.y.a. and the Dresbachian event about 502 m.y.a.

The Cambro–Ordovician event ended the Cambrian Period, and led into the Ordovician Period in the Paleozoic Era.

Theories

• Glaciation
• Depletion of oxygen in marine waters

See also

• End Botomian extinction event, circa 517 m.y.a.
• Dresbachian extinction event, circa 502 m.y.a.
• Geologic time scale
• Furongian, Late or Upper Cambrian period
• Early Ordovician period

Further reading

• Gradstein, Felix, James Ogg, and Alan Smith, eds., 2004. A Geologic Time Scale 2004 (Cambridge University Press).
• Hallam, A. and Paul B. Wignall, 1997. Mass extinctions and their aftermath (Oxford University Press).
• Webby, Barry D. and Mary L. Droser, eds., 2004. The Great Ordovician Biodiversification Event (Columbia University Press).

External links

• Early Ordovician Climate
• Speculated Causes For the Cambrian Extinction