James Stewart

After exchanging a few images, Jason Head booked his ticket to Florida that night.

The pair got to work immediately, honing in on the vertebrae from two different individual snakes.

And that's when Head spotted it.

The creature had a very clear T-shaped spine, with bones unique to only one type of animal, Boyd snakes, the lineage that includes boa constrictors and anacondas.

Now, both of these snakes are common in these parts.

Boas can reach up to 4.2 metres in length and anacondas can exceed 6 metres.

So that was nothing crazy, but something was wrong.

The bones they were looking at seemed to suggest this unknown creature was more closely related to boas, but where it had been found in Cerrejon was more akin to the habitat of a modern South American anaconda, a river and swamp dwelling snake comfortable in the water.

And there was another problem too.

You see, they still could not grasp the true size of just what they were dealing with.

Snakes are tricky.

They rarely end up being fossilized as their bones are very delicate and break, which means it's very hard to find an intact and complete skeleton.

But the team had one final trick up their sleeve.

Mathematics.

Up in Indiana, whilst the team in Florida had been analysing samples, another paleontologist, David Polley, had spent the last two years building what was essentially a mathematical model of how a snake's spinal column looks, based of course on living species.

Each bone corresponds to a specific region on the snake's back, but no one had really pieced that together before.

So Polly and Head put their heads together, and using this mathematical modeling, plotted each joint, ridge, and individual vertebrae as a set of coordinates on a graph.

And they were finally able to get an accurate picture of the snake's length.

What they unraveled was a 13 to 15 metre behemoth, weighing in with a mean of 1,135 kilograms, as much as some fully grown rhinos and the length of a school bus.

Titanoboa celihonesis, or Titanic boa constrictor, was formally named in 2009 in a Nature article, and it flipped evolutionary science on its head.