For scientists interested in what the world looked and felt like millions of years ago, coal mines are as good as it gets. While coal may be a major culprit in global warming, there is no place like a coal mine for studying climate change in the past and its likely effects on our own world. Mining companies know this, and for whatever reason, be it good citizenship or simply good public relations, they frequently lend paleontologists a hand.
Consider, for example, Cerrejón, an immense set of open pit coal mines in northern Colombia near the Caribbean coast. The pits are huge, circular, moonscape scars in the earth with shaley slopes that dump runoff water into green crater lakes where no plant dares grow and no bird dares swim. Once in a while, dynamite collapses part of the surrounding wall, and enormous cranes collect the coal while methane fires belch from fissures in the cliffs high above.
But there’s something else. The shale slopes at Cerrejón have preserved the fossil record of an entire tropical ecosystem as it existed 58 million years ago. By looking at the fossils, paleontologists can tell what the ancient climate at Cerrejón was like hotter and wetter than it is today and what the foliage was like very lush and similar to today’s Amazon jungle. The animals were huge. Cerrejón had river turtles with shells the size of kitchen tables that could seat six, and at the top of the food chain was Titanoboa cerrejonensis, a 45-foot, 2,500-pound serpent. Titanoboa was a true river monster—the largest snake ever known to have existed, and about five times the size of the Amazon anaconda, the biggest snake alive today.