Rare fossil 2 (biting ribs) (IMAGE) Canadian Museum of Nature Caption Detail of larger fossil, showing Repenomamus (mammal) biting the ribs of Psittacosaurus (dinosaur). Credit Gang Han Usage Restrictions For use with articles about the journal paper. 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.