Page Quinton, University of Missouri-Columbia (image) University of Missouri-Columbia Share Print E-Mail Caption Page Quinton verified evidence suggesting carbon dioxide decreased significantly at the end of the Ordovician Period, 450 million years ago, preceding an ice age and eventual mass extinction. These results will help climatologists better predict future environmental changes. Credit Jordan Yount, College of Arts and Science Usage Restrictions None Share Print E-Mail 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.