Scientists try to determine which giant animal was the apex predator 58 million years ago - a 43-foot-long snake called titanoboa or a giant crocodilian. A mining operation in Cerrejon, Northern Colombia, opened a window onto a previously unknown period of the earth's history and a world teeming with giant creatures emerged. The biggest of all was Titanoboa a 43-foot snake, the largest that ever lived. But new discoveries in Cerrejon suggest that Titanoboa's rule was challenged by a giant crocodilian. Follow scientists as they try to comprehend the size of this animal and uncover what made it so successful. Close analysis of fossils and scientific experiments reveal unmatched hunting prowess. So which one was the apex predator in Cerrejon 58 million years ago?