[Rockhounds] Fossil shells reveal both global mercury contamination and warming when dinosaurs perished

[Kreigh Tomaszewski]

The impact of an asteroid or comet is acknowledged as the principal cause
of the mass extinction that killed off most dinosaurs and about
three-quarters of the planet's plant and animal species 66 million years
ago.

But massive volcanic eruptions in India may also have contributed to the
extinctions. Scientists have long debated the significance of the Deccan
Traps eruptions, which began before the impact and lasted, on and off, for
nearly a million years, punctuated by the impact event
<https://phys.org/tags/impact+event/>.

Now, a University of Michigan-led geochemical analysis of fossil marine
mollusk shells from around the globe is providing new insights into both
the climate response and environmental mercury
<https://phys.org/tags/mercury/> contamination at the time of the Deccan
Traps volcanism.

>From the same shell <https://phys.org/tags/shell/> specimens, the
researchers found what appears to be a global signal of both abrupt ocean
warming and distinctly elevated mercury concentrations. Volcanoes are the
largest natural source of mercury entering the atmosphere.

https://phys.org/news/2019-12-fossil-shells-reveal-global-mercury.html