Chanares Formation Excavation (IMAGE) University of Utah Caption Co-author Adriana Mancuso (right) and Juan Martn Leardi (left) excavate the skeleton of the early mammal relative Massetognathus. This was also the site of one of the dated samples in the study. Credit Randall Irmis 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.