Greatest Mysteries: What Causes Mass Extinctions?
When you purchase through links on our website , we may earn an affiliate commission . Here ’s how it works . They are know ominously as the Big Five — the five greatestmass extinctionsover the past 500 million years , each of which is thought to have extinguish anywhere from 50 to 95 percent of all species on the major planet . Many unresolved mysteries remain regarding these disasters , perhaps the greatest of which is what caused each of them ....