Wednesday, March 4, 2009

Paleontologists Strike Fossil Gold in Colombia

With excerpts from:

BOGOTA, Colombia -- Carlos Jaramillo is 39 years old but loves to dig in the dirt -- especially the dry, flaky shale formations of Colombia's Guajira province. If you talk to a paleontologist, he explained, you're talking to a kid who never grew up. For the past five years, Jaramillo and his team of paleontologists have been burrowing ground so rich in fossils that they have made the kinds of discoveries that thrill the scientific world. And they still have years of digging ahead of them at this site in the Cerrejon region of northeastern Colombia, a remote and oven-hot place not unaccustomed to drug traffickers and the occasional rebel column.

Last month, an international group of scientists revealed in the journal Nature that Jaramillo's team had made a startling discovery -- a species of snake larger than a school bus that ruled northern South America 60 million years ago. Evolving after the extinction of the dinosaurs, Titanoboa cerrejonensis -- or titanic boa from Cerrejon -- might have been the largest vertebrate living on land at that time, the Paleocene era. Indeed, it had an average length of 43 feet -- far longer than any of today's pythons or anacondas -- and it weighed 2,500 pounds, more than a small car. Its diet included giant turtles and crocodiles -- Jaramillo's team also discovered the fossilized remains of those creatures under layers and layers of dirt and shale.
In all, Jaramillo and his team have found the remains of 28 snakes that measured between 42 and 49 feet. What we have is a population of big snakes, said Jaramillo, who is Colombian. It's not one snake. It's a bunch of them.

Funded by the Smithsonian Institution, Jaramillo's team -- the other members are students working on their master's or doctorate degrees -- has been digging in the most unusual of sites, the enormous, open-pit Cerrejon coal mine. Operated by some of the world's biggest mining multinationals, Cerrejon's 270 square miles are filled with moonlike craters 300 feet deep.
Excavators and earth movers work without pause, carting off 32 million metric tons of coal a year. They also remove rock and dirt that the paleontologists would never be able to budge -- making it much easier for Jaramillo's team to reach the valuable fossils that he said are opening a window on the first tropical forests that evolved after the dinosaurs disappeared. They close a pit, and then they open up a new pit, so we always have possibilities, Jaramillo said. I think we'll have 10, 15 years to do excavations. We always find new things.

Arriving for a dig a few months ago, Jaramillo scanned the horizon. For a first-time visitor accompanying him, it appeared to be anything but ground zero for fossils. Huge trucks roared past carrying mounds of coal to be exported to Europe and the United States, and heavy machinery could be heard in the distance, kicking up clouds of dust. Wearing white work helmets, Jaramillo and two members of his team descended into one of the pits. They carried the tools of their trade -- a light chisel to brush off dirt and hand lens to examine their discoveries. Perhaps even more important is simply having a sharp eye and a soft touch. You need to train your eyes and you need to have special skills to do that, Jaramillo explained. If you don't have the skills, you will come here for a year and never find anything.

The team's work has already turned up giant crocodiles and freshwater turtles that weighed 300 pounds. There are also hundreds of fossils of leaves so perfectly preserved that the paleontologists can easily make out the veins and ridges. Oh my God, you can tell the venation very well! Jaramillo exclaimed, examining a leaf belonging to the Araceae plant family. This is 60 million years old. So it's probably one of the oldest Araceaes ever found. He then showed off the remains of a recently discovered anaconda, and then the fossils of fish and crabs, too. This was like a big delta, it was a tropical rain forest, he said. That may be hard to fathom today because it rarely rains in Guajira province, which is now mostly home to scrub grass and small trees.

Jaramillo and other scientists think the forest that once thrived in Cerrejon evolved after a giant meteorite hit Yucatan Peninsula. The fossils they are recovering are helping to explain how the forest responded to that environmental catastrophe -- and may provide clues on how the modern world will react to, say, global warming. The team's discoveries are piling up -- 4,000 fossils of plants, fruit, flowers and seeds; 75 turtles, 25 crocodiles, as well as fish, crabs and other creatures. The fossils belong to Colombia but are on loan to the Smithsonian Tropical Research Institute in Panama and at the University of Florida at Gainesville.

Still, Jaramillo searches for more. He said each find is like the chapter of a book. Pieced together, they tell a long and complex story, one that he said is not yet complete. The feeling is amazing, because we don't know if here we're going to have a fantastic flower nobody has seen for the last 60 million years, or perhaps there is nothing, he said, as he took a chisel to a mound he had recovered from the shale. So you just crack the rock open and hope for the best.