Small Fish of the Mississippian (IMAGE) University of Pennsylvania Caption After the Hangenberg mass extinction, small fish dominated the oceans while larger fish mostly died out. Credit Bob Nicholls Usage Restrictions In context of reporting 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.