The giant snake that stalked the Earth
A recently discovered prehistoric monster snake provides answers about the past - and raises questions for the future.
Around 58 million years ago, a monstrous snake slithered out of the swampy jungles of South America and began a reign of terror.
Weighing more than a tonne and measuring 14m (approximately 50ft) the giant reptile could swallow a whole crocodile without showing a bulge. But a few years ago, scientists never even knew it existed.
"Never in your wildest dreams do you expect to find a 14m boa constrictor. The biggest snake today is half that size," says Dr Carlos Jaramillo, a scientist with the Smithsonian Tropical Research Institute and part of the team that made the discovery.
'World of lost reptiles'
Thought to be a distant relative of the anaconda and boa constrictor, the snake - namedTitanoboa- was not venomous. Instead, it crushed its prey with the constricting force of 400lbs per sq inch - the equivalent of lying under the weight of one and a half times the Brooklyn Bridge.
The fossils were exposed by excavation at the massive Cerrejon open-face coal mine in northern Colombia. In 2002, scientists had discovered at that site the remains of a tropical rainforest from the Palaeocene Epoch - perhaps the planet's first.
As well as fossilised leaves and plants, they unearthed reptiles so big they defied imagination.
"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, an expert in vertebrate evolution at the University of Florida.
They also found the vertebrae of a colossal snake.
"After the extinction of the dinosaurs, this animal, theTitanoboa, was the largest predator on the surface of the planet for at least 10 million years," says Dr Bloch. "This was a major animal in any sense of the imagination."
Search for skulls
But scientists needed the snake's skull to get a full picture of how it looked, what food it ate and how it might be related to modern species. Last year, a team set out to find it, with little expectation of success. Because the bones of a snake's skull are so fragile, few survive.
"Unlike our skulls, snake skulls aren't fused together. Instead they're connected with tissue," says Dr Jason Head, a snake specialist from the University of Nebraska.
"When the animal dies, the connective tissue decomposes and all the individual bones are generally dispersed. They're very thin and fragile too and often get destroyed. BecauseTitanoboais so big and the skull bones are so large, it's one of the few snakes that do make it into the fossil record."
To their amazement, the team recovered the remains of three skulls from which the reptile could be accurately reconstructed for the first time.
From that, they were able to get a better sense of howTitanoboalived and looked. A life-sized replica is now on display at the Smithsonian Natural History Museum in Washington, and will begin a nationwide tour in 2013.
Aside from the excitement of discovering a new and enormous species of snake, the reptile can tell scientists a lot about the history of the Earth's climate - and offer a glimpse of the possible effects of global warming today.
Snakes are unable to regulate their own temperature and depend on external heat to survive.
"We think theTitanoboabecame this large because it was much warmer on the equator after the dinosaurs died 60 million years ago," says Dr Bloch. "We think that's why reptiles in general were larger.
That ability to thrive in a warm climate could be relevant in the event that global temperatures rise according to the projections of climate scientists, Dr Bloch adds.
"It's evidence that ecosystems can thrive at temperatures of the levels that are being projected over the next one or two hundred years."
But the climate changes that producedTitanoboatook millions of years. Scientists are less certain about the effects of sudden temperature change.
"Biology is amazingly adaptable. Changing climates and changing continents are the fuel of evolution. But things that happen very quickly can result in the types of change we might not view very positively," says Dr Bloch.
As well as being warmer, CO2 levels were also 50% higher during the period of the Cerrejon rainforest.
"One big lesson we are learning from the fossils in Cerrejon is that tropical plants and the ecosystem in general have the ability to cope with high temperatures and high levels of CO2, another major concern with the current trend of global warming," says Dr Jaramillo.
"Perhaps the plants and animals of the tropics today already have the genetic ability to cope with global warming."
Does that mean theTitanoboacould one day return?
"As the temperature increases, you have the probability they will come back," says Dr Jaramillo. "But it takes geological time to develop a new species. It could take a million years - but perhaps they will!"