That' a pretty big snake.

The largest known snake that ever lived grew as long as a school bus, was 3 feet thick, weighed over a ton and ate crocodiles " presumably whole and al dente.

Not to worry: Titanoboa cerrejonensis lived 60 million years ago and is extinct. But for some 20 million years after the dinosaurs disappeared, this 42-foot serpent ruled the land.

Scientists discovered enormous vertebrae from a Titanoboa in a coal mine in Colombia. The spinal column bones were 5 inches across, more than twice the size of the biggest South American boa constrictor or anaconda.

"I just about jumped out of my chair," says paleontologist Jason Head of the University of Toronto, recalling the moment he first saw one of the bones. He said he couldn't help but laugh "because it was so ridiculously big. I said I know this is the world's largest snake."

Head, who specializes in the fossils of giant reptiles, says the snake probably lived part of the time in the water, like present-day anacondas. It was the largest vertebrate on land after the dinosaurs disappeared and probably would have killed its prey by squeezing them.

In this week's issue of the journal Nature, Head points out that a cold-blooded animal that big would have had to live in a very hot place to survive. According to his calculations, the average temperature would have been about 90 degrees. That's several degrees warmer than the present-day tropical average and is warmer than scientists believed the tropics ever got, even during ancient periods of greenhouse warming.

Conventional wisdom holds that during global warming events, the tropics don't heat up as much as polar or temperate regions, according to climate scientist Matthew Huber of Purdue University. He says that if Head is right about Titanoboa's toasty climate, "that's in some sense bad news for us for the future.

"It says there's no magical thermostat that keeps the tropics at a reasonable temperature, that they will warm, too, in a global warming world," Huber notes.

At the same time, he says, it also suggests that if the tropics do warm up a lot during warming events, they can survive those higher temperatures " at least well enough to provide a habitat for giant serpents.