Dana Royer, assistant professor of earth and environmental science, presented his research on leaf economics at the Geological Society of America in October. Posted 1./1./6/font> Many scientists have long believed a major clue to rapid global warming is locked in leaf fossils that are millions of years old. Dana Royer, assistant professor of earth and environmental science, has just found a key. Royer and colleagues have generated a reliable method to ascertain from fossils from the Eocene period, 34 million to 56 million years ago, the leaf mass per unit of leaf area, an important trait that is related to…