Writer Fuel: Did UV Radiation Cause a Mass Extinction Event on Earth?

A lethal pulse of ultraviolet (UV) radiation may have played a role in Earth's biggest mass extinction event, fossilized pollen grains reveal. Pollen that dates to the time of the Permian-Triassic mass extinction event, roughly 250 million years ago, produced "sunscreen" compounds that shielded against harmful UV-B radiation, the analysis found. At that time, approximately...