Researcher in the Field (IMAGE) U.S. National Science Foundation Caption Ellen Currano collecting fossil leaves from a site that is 57 million years old in the Bighorn Basin, Wyoming. Credit Credit: Photo by Ellen Currano 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.