Shrinking Coyotes

Many animals used to be a lot bigger. When the last ice age ended more than 10,000 years ago, many large species of mammals went extinct and others underwent changes in appearance. What caused these evolutionary changes? A study by Julie Meachen of the National Science Foundation (NSF) National Evolutionary Synthesis Center and Josh Samuels of the John Day Fossil Beds National Monument reveals that gray wolves and coyotes, once more similar in size, took the extinction in different strides. The coyotes shrunk while the wolves did not. Coyotes changed from large, pack-hunting dogs to the smaller canines we know today and wolves essentially remained the same. Changes in body size occurred for coyotes because large prey and their large competitors were disappearing, the researchers find. Today's gray wolf is five to six feet from nose-to-tail; modern-day coyotes measure three to four feet. Gray wolves usually weigh 80 to 120 pounds; coyotes, in comparison, weigh a mere 30 to 40 pounds.