Tooth close up (IMAGE) University of Colorado at Boulder Caption A fossilized Sikuomys mikros tooth about the size of a grain of sand seen under the microscope. Credit Jaelyn Eberle Usage Restrictions Use with credit 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.