In Mexico, construction workers digging the foundations for a new airport made a startling discovery: woolly mammoth bones. The dig site is about 30 miles from Mexico City. And researchers say the boneyard is one of the world’s largest deposits of mammoth remains. They estimate it’s the final resting place for at least 100 of the extinct mammals. And there may be more bones yet to find. Woolly mammoths are relatives of today’s elephants who walked the earth 10,000 years ago.