Mouse Fossil (IMAGE) DOE/SLAC National Accelerator Laboratory Caption The key fossil examined in this study is a 3-million-year-old extinct species of field mouse from Germany. The mouse is approximately 7 cm long. Credit University of G?ttingen 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.