In 2009, a group of passionate scientists stumbled upon fossils of the titanoboa - the biggest snake of all time. At 48 feet long and weighing well over a tonne, the snake is one of the greatest discoveries since the T-rex. The animal is a relative of modern boa constrictors and lived in the rainforest of north-east Colombia 58-60 million years ago. The spectacular palaeontological find deep in the Cerrejon coal mines in Colombia has blown the doors off a lost period in prehistory. They had unexpectedly discovered a time after the dinosaurs when the world was once again ruled by super-sized reptiles, battling it out to become the planet's top predators; among them, the gargantuan titanoboa. Using pin-sharp CGI and scintillating cutting-edge science, the programme brings back the real lost world.