Titanoboa, largest prehistoric snake discovered in Colombia

The discovery of world's largest prehistoric snake is reported in today's issue of Nature. The snake, named Titanoboa cerrejonensis, a relative of the Boa constrictor, was 13 metres (42 feet) long, weighed 1,140 kilograms, and would have required temperatures that are hotter than in today's tropics. The finding calls into question the idea that the climate system has a 'thermostat' that regulates tropical temperatures.

Excavations in the Cerrejon Coal Mine, N Colombia by Carlos Jaramillo form the Smithsonian Tropical Research Institute in Panama and Jonathan Bloch, curator of vertebrate palaeontology at the University of Florida's Florida Museum of Natural History, unearthed a 60-million-year-old fossil remains of a this new snake species.

'At its greatest width, the snake would have come up to about your hips,' said Indiana University Bloomington geologist David Polly, who identified the position of the fossil vertebrae, which made a size estimate possible. 'The size is pretty amazing. But our team went a step further and asked, how warm would the Earth have to be to support a body of this size?'

Titanoboa's size indicates that it lived in an environment where the average yearly temperature was 30-34 degrees Celsius. This estimate coincides with palaeoclimatic models predicting greenhouse conditions. 'This temperature estimate is much hotter than modern temperatures in tropical rainforests anywhere in the world. The fossil floras that the Smithsonian has been collecting in Cerrejon for many years indicate that the area was a tropical rainforest. That means that tropical rainforests could exist at temperatures 3-4 degrees Celsius hotter than modern tropical rainforests experience,' said Jaramillo.

'Tropical ecosystems of South America were surprisingly different 60 million years ago,' said Bloch. 'It was a rainforest, like today, but it was even hotter and the cold-blooded reptiles were all substantially larger. The result was, among other things, the largest snakes the world has ever seen... and hopefully ever will.'

The scientists classify Titanoboa as a boine snake, a type of non-venomous constrictor that includes anacondas and boas. Jason Head, a research associate at the Smithsonian's National Museum of Natural History, with David Polly, associate professor of geosciences at Indiana University, extrapolated the placement of Titanoboa fossil vertebrae by comparing the fossils' structure to the vertebrae of today's boine snakes. Snake vertebrae get bigger near a snake's midsection, but they are also structured differently than vertebrae closer to a snake's head or tail. Using a computer model he wrote, Polly estimated the fossil vertebrae originate near Titanoboa's middle. That means that if Polly's model is incorrect about the bone's placement, the snake could have been even bigger.

Evolution has produced a wide variety of gigantic animals over the last several hundred million years - dinosaurs, ancient dragonflies, and today's blue whale, to name a few; but why some species lineages produce monsters remains a matter of debate among evolutionary biologists and ecologists.