The First Mass Extinction Event Explained: End-Ordovician July 11, 2022, 07:14:51 AM The First Mass Extinction Event Explained: End-Ordovician[html]How long did the Ordovician period last, and what caused the Ordovician mass extinction to wipe out 85 percent of life on earth 445 million years ago?[/html]Source: The First Mass Extinction Event Explained: End-Ordovician (http://ht**://www.discovermagazine.c**/the-sciences/the-first-mass-extinction-event-explained-end-ordovician) Quote Selected