Back in the Middle to Upper Miocene eras, which took place around 12 million years ago, the world was quite a bit warmer, which meant that plants and animals could grow a lot larger.

This explains why there are so many absolutely massive animals in the fossil record during this time. As the temperatures dropped, however, these huge animals either slowly shrank in size or else they went extinct, since the environment could no longer support them.

So, when researchers studied the fossils from ancient anacondas, they expected to see a snake that was beyond huge. Afterall, the modern anaconda is already far bigger than most other snakes.

What they found, however, was that the snake was more or less the same size as it is today, which was quite unexpected.

In a statement about their efforts, lead author Andres Alfonso-Rojas, who is a PhD student and Gates Cambridge Scholar in the Department of Zoology at the University of Cambridge, said:

“This is a surprising result because we expected to find the ancient anacondas were seven or eight metres long. But we don’t have any evidence of a larger snake from the Miocene when global temperatures were warmer. By measuring the fossils, we found that anacondas evolved a large body size shortly after they appeared in tropical South America around 12.4 million years ago, and their size hasn’t changed since.”

The study, which was published in the Journal of Vertebrate Paleontology, suggests that their ability to maintain their size likely comes from the area of the world in which they live.

Anacondas are found in swamps, near rivers, in marshes, and in other very wet and warm areas. These parts of the world are able to support a lot of wildlife, including the many animals that the anaconda preys on.

It can even be said that these areas of the world are the most similar to how the whole planet was during the area where giant animals were the norm.

Most other large animals died out or evolved to be smaller, but not this impressive snake. Alfonso-Rojas said:

“Other species like giant crocodiles and giant turtles have gone extinct since the Miocene, probably due to cooling global temperatures and shrinking habitats, but the giant anacondas have survived. They are super-resilient.”

If climate change has a significant effect on these habitats, however, it may be possible that the anaconda finally goes through the same thing that all these other massive animals experienced. Let’s hope we never have to find out.

If you think that’s impressive, check out this story about a “goldmine” of lithium that was found in the U.S. that could completely change the EV battery game.