PBS Eons has another interesting episode.  This one is about the Permian Mass Extinction, which is often referred to as the "Great Dying" as more than 90% of all species went extinct during this event.  The cause is thought to be massive flood basalt volcanic eruptions in what is now Siberia about 250 million years ago.

A catastrophic volcanic event in the Late Permian Period caused the biggest mass extinction of all time – known to us as the Great Dying. As a result, a large majority of terrestrial life would disappear, but our ancestors had the adaptations (and the healthy dose of luck) needed to survive – but would you?