Sarah Gabbott, University of Leicester (IMAGE) University of Leicester Caption Professor Sarah Gabbott on fieldwork in Illinois digging for new fossil specimens. In her hand is a hard nodule formed 300 million years ago on a warm, shallow sea floor. Credit Thomas Clements Usage Restrictions None 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.