Dental CT scans (IMAGE) Duke University Caption Dental CT scans show that mammal teeth became less diverse during the early Oligocene extinction events. Here is an example of the three-dimensional tooth shape of a lower molar of a fossil anomaluroid rodent. Credit Dorien de Vries, University of Salford 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.