Mammoth Bones (IMAGE) University of Wyoming Caption These are the remains of a mammoth that was killed by humans near LaPrele Creek in Converse County, Wyo., about 13,000 years ago. New University of Wyoming research shows wide variation in the rates at which the bones of ancient animals in the Americas have been lost. Credit Danny Walker and Wyoming State Archaeologist's Office Photo 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.