Solving a Mass Murder (IMAGE) Washington University in St. Louis Caption Washington University in St. Louis geologist David Fike holds a 443-million-year-old slab of Ordovician limestone from Anticosti Island in Quebec that is sprinkled with the fossilized remains of marine creatures killed during a cooling pulse. New research suggests the mass extinction, which took place 440 million years ago was caused by a sequence of events that allowed volcanoes to inject reflective aerosols above the tropopause. Credit Jerry Naunheim Jr./WUSTL Photos. Usage Restrictions Please credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.