CT scans of prehistoric mammals' skulls (IMAGE) University of Edinburgh Caption Crania and virtual endocasts inside the translucent cranium of the Paleocene mammal Arctocyon (left) and the Eocene mammal Hyrachyus (right) Credit Ornella Bertrand and Sarah Shelley Usage Restrictions None License Original 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.