Scientists Say Weight-Loss Substance May Have Caused Elk Deaths in Wyoming Mar 25, 2004 By Mead Gruver/ Associated Press Writer / CHEYENNE, Wyo. (AP) - A substance found in some weight-loss diet supplements - and in a type of lichen - may have fatally poisoned more than 300 elk in Wyoming in recent weeks, scientists say. Scientists theorize the substance, usnic acid, may have caused the animals to weaken and collapse - too helpless to eat, drink or escape predators. The chemical was extracted from tumbleweed shield lichen, which grows on the ground in many northern states. Captive elk fed...