Around 65.5 million years ago, an asteroid about six to nine mi — or 10 to 15 km — in …

http://www.depopulation.news/2017-08-29-just-one-asteroid-strike-thrust-the-planet-into-years-of-darkness-killing-almost-everything.html

Geologists now believe that a massive volcanic eruption was the cause of the late Ordovician mass extinction. This is the …

http://www.depopulation.news/2017-07-30-a-single-volcanic-eruption-caused-one-of-the-planets-most-devastating-mass-extinctions-scientists-discover.html