It’s the stuff of nightmares – a giant snake so big that it could barely have squeezed through a modern door; as long as a bus and weighing more than a ton. It could swallow a crocodile whole, opening its jaws to almost 180 degrees.

It’s thought to be a relative of the anaconda and the boa of today, and it’s been given the name titanoboa.

It lived around 58 million years ago, at a time when the dinosaurs were no more, and the world had become hotter. That heat helped cold-blooded creatures like snakes. Their body temperature is controlled by the heat they getr; and the greater the heat, the more they can grow. Titanoboa lived in a world of lush tropical plants, grown large in an atmosphere where carbon dioxide levels were higher than today. There were early bean, banana and chocolate plants, tropical rainforests in wetlands, an ideal habitat for reptiles.

“What we found was a giant world of lost reptiles – turtles the size of a kitchen table and the biggest crocodiles in the history of fossil records,’ says Jonathan Bloch of the University of Florida.”

And how they found the lost world was through the fossils it left behind. These fossils have been uncovered in a massive open-case coal mine in northeastern Colombia at Cerrejon.

Amongst the fossils of leaves and plants and reptiles, an expedition in 2004 found the vertebrae of a colossal snake. From those pieces, they began to build up a picture of how it looked.

To get a fuller picture of titanoboa, a skull was needed, and that was going to be a challenge. A human skull consist of bones fused together, and so survives as a single unit. But a snake’s skull consists of many small bones held together with tissue; and when the snake dies the tissue decays and the bones are scattered.

“They’re very thin and fragile too and often get destroyed,’ says Dr Jason Head of the University of Nebraska. ‘Because titanoboa is so big and the skull bones are so large, it’s one of the few snakes that do make it into the fossil record.”

When Jonathan Bloch and Jason Head went to Cerrejon, they had little hope of finding a skull of the giant snake. But indeed, the sheer size of the creature led to success for them – the discovery of the remains of three skulls of titanoboa. This meant that the reptile could be accurately reconstructed for the first time. And now a life-size replica has been created and you can see it on film on the Smithsonian Channel.