Mass Extinctions: The 5 Biggest Dying Events in History

In this episode of Earth SciShow, MrEarthGuy discusses Mass extinctions. They indicate the disappearance of large numbers of species and have occurred throughout Earth's history. In fact, scientists estimate that at least 99.9 percent of all species of plants and animals that ever lived are now extinct. So why should we care about mass extinctions? and why did they occur? Tune in to find out!