It was the mother of all snakes, a nightmarish behemoth as long as a school bus and as heavy as a Volkswagen Beetle that ruled the ancient Amazonian rain forest for 2 million years before slithering into nonexistence.
Now this monster, which weighed in at 2,500 pounds, has resurfaced in fossils taken from an open-pit coal mine in Colombia, a startling example of growth gone wild.
Modern boas and anacondas, which average less than 20 feet in length and reach a maximum of 30 feet, have been known to swallow Chihuahuas, cats and other small pets, but this prehistoric monster snacked on giant turtles and primitive crocodiles.
"This is amazing. It challenges everything we know about how big a snake can be," said herpetologist Jack Conrad of the American Museum of Natural History in New York, who was not involved in the research.
The snake's estimated length, 43 feet, "is the same as the largest Tyrannosaurus rex that we know of, although it only weighs one-sixth as much," he said.
The find not only sheds new light on snake evolution; it also provides telling insights on climate. The snake flourished about 58 million to 60 million years ago. Because Titanoboa cerrejonensis, as it has been named, was coldblooded, the tropical climate had to be 6 to 8 degrees warmer than it is today for a snake that large to survive, said evolutionary biologist Jason Head of the University of Toronto at Mississauga, lead author of a paper on the fossils appearing today in the journal Nature.
The remains of several specimens of the snake are from a cache of fossils excavated from El Cerrejon coal mine in northern Colombia. Paleontologists are excited about the find because there are few fossils of tropical vertebrates from the period after the demise of the dinosaurs 65 million years ago.
Most rock outcroppings that might contain fossils have been hidden by the region's dense foliage, said paleontologist Jonathan Bloch of the University of Florida, who identified the snake.
"The entire 10-million-year period following the extinction of the dinosaurs is a blank slate," he said.
Bloch and his students identified hundreds of specimens that had been dug from the mine, including "the largest freshwater turtle ever known" and "beautifully preserved skeletons" of an extinct species of crocodile "known to have been in South America, but never seen [there] before."
They also found fossils of a variety of fish, related to bonefish and tarpon, that would have lived in brackish seawater. "That indicates it was a big, riverine system close to the ocean," Bloch said.
They also found 28 snakes in the 42-to-45-foot range.
Titanoboa probably was the largest nonmarine creature on Earth during that period, Head said.
The turtles and crocodiles that the team excavated were probably the giant snake's primary diet, Head said.
Snakes are generally able to swallow prey that weighs about the same as they do, Conrad said. Titanoboa "could eat a large cow or a bison" -- if any had been around.
Instead, it probably had to settle for other reptiles, sliding into the water and gulping them down in ferocious strikes.
Because snakes and other reptiles are coldblooded -- technically, poikilothermic -- they rely on heat in the environment. Generally, the farther from the equator that a reptile lives, the smaller it has to be.
Extrapolating from the energy requirements of modern snakes, the team estimated that Titanoboa required an average temperature of 86 to 93 degrees Fahrenheit, somewhat higher than the modern average of about 83 degrees in coastal Colombia.
This sheds some light on current theories about what happens at the equator during periodic bouts of natural global warming. One school of thought holds that temperatures at the equator are buffered, staying relatively constant while more northern and southern latitudes heat up.
"These findings support the idea that with a warmer world, the equator was also warmer," Bloch said.
Researchers now believe that the climate got even hotter after the time of the Titanoboa, perhaps hastening the snake's demise.
"Big animals went extinct because it simply got too hot," Conrad said. "This helps us to understand that the effects of global warming aren't just rising sea levels."