Stunned scientists have found the fossilised remains of the world's greatest snake -- a record-busting serpent that was as long as a bus and snacked on crocodiles.
The boa-like behemoth, dubbed Titanoboa, ruled the tropical rainforests of what is now Colombia some 60 million years ago, at a time when the world was far hotter than now, they report in a study .
The size of the snake's vertebrae suggest the beast weighed some 1.135 tonnes, in a range of 730 kilos (1,600 pounds) to 2.03 tonnes.
And it measured 13 metres (42.7 feet) from nose to tail, in a range of 10.64-15 metres (34.6-48.75 feet), they estimate.
"The discovery of Titanoboa challenges our understanding of past climates and environments, as well as the biological limitations on the evolution of giant snakes," said Jason Head, member of the Panama-based research institute and lead author of the study to be published in Nature magazine.
"This shows how much more information about the history of Earth there is to glean from a resource like the reptile fossil record," said the assistant professor of ecology and evolutionary biology at the University of Toronto Mississauga.
From the size of the 1.14-tonne Titanoboa, scientists have estimated the average annual temperature in the tropical jungle it inhabited 60 million years ago at 30-34 degrees Celsius (86-93 degrees Farenheit).
"This temperature estimate is much hotter than modern temperatures in tropical rainforests anywhere in the world," said Carlos Jaramillo, Smithsonian staff scientist and co-organizer of the excavations in Colombia.
"That means that tropical rainforests could exist at temperatures 3-4 degrees Celsius hotter than modern tropical rainforests experience," he added, alluding to scientific theories that would have tropical forests disappear if global warming boosts temperatures by that measure in the future.
Jonathan Block, a vertebrate palaeontologist at the University of Florida, who co-led the work said "Truly enormous snakes really spark people's imagination, but reality has exceeded the fantasies of Hollywood."
"The snake that tried to eat Jennifer Lopez in the movie 'Anaconda' is not as big as the one we found."
"At its greatest width, the snake would have come up to about your hips," said David Polly, a geologist at the University of Indiana at Bloomington.
The investigators found the remains of the new species at an unlikely location -- at one of the world's biggest open-cast coalmines, in Cerrejon, Colombia, where giant machines had obligingly gnawed away surface layers of dirt.
Working as huge coal-laden trucks thundered by, the team sifted through the earth, laying bare the remains of supersized snakes and their likely prey -- extinct species of crocodiles and giant turtles -- and evidence that a massive rainforest once covered the ground.
"The giant Colombian snake is a truly exciting discovery. For years, herpetologists have argued about just how big snakes can get, with debatable estimates of the max somewhere less than 40 feet" (12.3 metres), said leading snake expert Harry Greene of Cornell University, New York.
Titanoboa cerrejonensis -- whose Latin name honours the coal mine -- is not only a source of jaw-dropping wonder.
It is also a useful indicator as to the world's climate after the dinosaurs were wiped out some 65 million years ago, the team say.
Unlike mammals, reptiles cannot regulate their own temperature.
As a result, they are limited in body size by the ambient temperature of where they live. For example, reptiles today are bigger in the tropics than they are in cooler latitudes.
Based on T. cerrejonensis, the scientists calculate that the mean annual temperature in equatorial South America 60 million years ago would have been 30-34 degrees Celsius, or 86-93 degrees Fahrenheit.
That makes it around 3-4 C (5.5-7.2 F) hotter than tropical rainforests today.
If so, this is a welcome piece of news about climate change.
Simulations about global warming suggest that, on present trends, the world's surface temperatures could rise by between 1.8-4.0 C (3.2-7.2 F) by 2100.
If the supersnakes are a guide, tropical rain forests could still exist at such temperatures, although a fast, massive rise in warming could well be devastating to many species.
The paper is published by the British-based weekly science journal Nature.
The world's longest snake today is the Asian reticulated python, specimens of which can grow around 10 metres (32.5 feet), and the biggest in terms of mass is the green anaconda, with some specimens weighing 227 kilos (550 pounds).
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