Jessica Theodor, University of Calgary (IMAGE) University of Calgary Caption Paper co-author Dr. Jessica Theodor, University of Calgary, holds a skull of Hyaenodon, a large early carnivorous mammal from a group known as the Creodonta which lived between 42 and 15.9 million years ago. Credit Riley Brandt/ University of Calgary 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.