Horse Tooth (IMAGE) PLOS Caption This fossilized horse (Equus) tooth shows where a series of enamel samples have been drilled to help identify seasonal fluctuations in the animal’s diet. This horse lived ~1.9 million years ago during a glacial period in Florida. A paper by University of Florida researchers appearing in the DATE issue of the journal PLoS ONE has found that ancient mammals altered their diets in response to past global warming. Credit Mary Warrick, <i>PLoS ONE</i> 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.