What Caused the Largest and Most Gruesome Massacre in Earth History?

The horrifying slaughter of an entire continent

Roughly 2.7 million years ago, something happened that led to massive extinction rates of the mammals of an entire continent—roughly 50 to 70% of its furry genera. And the wide-scale death was not caused by any of the usual suspects—erupting volcanos, rising seas, expanding deserts, creeping glaciers, atmospheric changes, spreading disease, or asteroid …