Most people have never heard of the Cerrejón coal mine, located in Colombia. The mine pumps out over 30 million tons of coal each year, and it's also become a critical site for scientists. In fact, the coal mine ranks as one of the best fossil sites in the world, providing a window into a tropical rain forest from 60 million years ago. Scientists almost missed the fossils at Cerrejón - until an undergraduate noticed a surprising number of sandstone impressions of fossil leaves. His discovery led to an expedition that found multiple new species, including the largest snake in history.