Fraiser with Fossil Record of Bivalves (image) University of Wisconsin - Milwaukee Caption Margaret Fraiser, UW-Milwaukee assistant professor of geosciences, shows fossils of the few survivors of the Permian-Triassic mass extinction, the most severe in Earth's history. Credit Alan Magayne-Roshak, UW-Milwaukee Usage Restrictions with the above photo credit. 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.