Monday, January 25, 2021

The Ordovician Extinction

The only thing certain about living on planet earth is change. From Discover Magazine:

But many researchers are beginning to think that “cooling itself may not be solely responsible for these extinctions,” as Thijs Vandenbroucke and colleagues wrote in a 2015 paper that links some deaths to changing ocean chemistry. They found fossilized plankton with fatal deformities dating to the event, suggesting the release of toxic metals like iron and lead from the ocean depths may have been an important kill mechanism.

Some evidence in recent years even points the finger at glaciation’s elemental opposite: volcanism. The Ordovician extinction, if caused by the cooling climate, would be an outlier. Extreme volcanic activity is widely accepted as a main catalyst in most other mass die-offs, since it leads to inhospitable global warming. Now, with the discovery of mercury deposits from the era, the telltale signature of eruptions has surfaced in this extinction too. Rewriting the story with a fiery culprit would “make the late Ordovician stand out less,” Finnegan says, though he’s not convinced yet. (Read more.)


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