5 Prehistoric Snakes (One Was the Size of a School Bus!)

Written by Kristen Holder
Updated: June 4, 2023
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Snakes as we know them have been slithering on the planet since about 145 million to 65 million years ago. Snakes probably came from the Mediterranean Tethys, a strip of water that existed on the planet as the continents were shifting.

There’s some debate about whether snakes originated in the water or if land snakes developed on land, which means there must be some pretty cool fossil records about prehistoric snakes.

While the fossil records are woefully incomplete, some prehistoric snakes are worth a closer look. Let’s look at five prehistoric snakes with our list ending on one as big as a school bus!

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5. Palaeophis Colossaeus

The largest sea snake to have existed could eat whale calves.

©Nobu Tamura (http://spinops.blogspot.ca/) / Creative Commons – License

The Palaeophis Colossaeus went extinct about 33 million years ago, and it was the largest sea snake (not a land snake!) ever. It’s believed to have been up to 30 feet long, and it may have fed on animals as large as whale calves.

It’s believed that it could get so big because sea temperatures were higher, which were the perfect conditions for the snake to get so large. It could keep itself warm despite its size. Snakes are cold-blooded, which means they respond to ambient temperature. They’re more active when it’s hot and dormant when it’s cool.

What leads experts to think that sea temperature is one of the reasons that Colossaeus was so large is that its vertebrae show there were a lot of veins and arteries, which means it must have had a faster growth rate and metabolism than extant snakes have.

Its spine was stiffer than modern snakes, and it swam a lot more. Its stiff spine may have helped it swim better, but it meant it could not constrict its prey.

It’s believed this snake was nonvenomous. Its jaw was its weapon of choice. It may have given live birth.

4. Coniophis Precedens

Snake Skeleton Closeup

The disjointed jaw of modern snakes didn’t exist in Coniophis Precedens.


Coniophis Precedens was a little snake that averaged about 2.75 inches in length. It went extinct around 65 million years ago. Its fossils have been found in ancient floodplains, suggesting that it enjoyed spending most of its time on land.

This snake was long and had teeth like a snake, but its bone structure was more like a lizard than a modern snake. Its skull was somewhere between a lizard and a snake which has piqued the interest of curious scientists looking to unravel the mysteries about the origins of the snake.

It probably chowed down on vertebrates, salamanders, and small lizards. It doesn’t have the disjointing jaw of modern snakes, so only what fit through its mouth could be consumed.

It is the most primitive snake as far as development, but it isn’t the oldest snake to have ever existed. That title belongs to Eophis underwoodi, which was alive 167 million years ago. It is believed that Coniophis precedens evolved from burrowing lizards.

The theories now suggest that slithering was the evolutionary goal, not swimming. Almost 3,000 snake species alive today probably have their ancient origins, with Coniophis precedens.

3. Najash Rionegrina

The snakes alive today have ancestors with hind legs.

©Own work / Creative Commons – License

The Najash Rionegrina was around about 95 million years ago, and it was the first land snake with hind legs that’s been discovered. Snakes have evolved from aquatic or land lizards that adapted over time to swimming and burrowing by losing their hind legs.

Before discovering Najash Rionegrina, only aquatic snakes had been discovered with legs. Najash Rionegrina was the first land snake to have real legs, and it throws a lot of theories about snake evolution into question.

Snakes were believed to have come from animals similar to the small, blind, and burrowing snakes that exist today. However, the Najash Rionegrina skull suggests that snakes evolved from animals like the Komodo dragon, not tiny blind snakes.

It also suggests that once a snake’s ancestor emerged from the water, they went through a distinct lizard-like phase before becoming real terrestrial snakes. Previously, it was believed that this legged period was just an intermediary phase between the ocean and land life.

2. Yurlunggur Camfieldensis

Y. camfieldensis was part of the megafauna in Australia that existed 5 million to 30 million years ago. Its fossils suggest that it could grow up to 20 feet in length.

Like the Najash Rionegrina, its fossils suggest that the snake’s ancestors are not small burrowers but animals about the size of a monitor lizard. This is like the conclusion drawn regarding Najash Rionegrina.

1. Titanoboa (Longer Than a School Bus!)

titanoboa size

Titanoboa was longer than the average school bus.

©Michael Rosskothen/Shutterstock.com

The Titanoboa is our #1 prehistoric snake because it was massive. It was longer than a school bus!

It was up to 50 feet long and weighed over 2,500 pounds. Yet no one is quite sure how this monster lived its life. There’s a lot of debate about what it ate and how it attacked its prey. Some believed that it would have constricted its prey since it was a massive boa constrictor. It probably mainly ate fish, though some believe it also ate dangerous prey like alligators.

Fossil records indicate that this creature lived about 60 million years ago and thrived in the time right after the extinction of the dinosaurs. It most likely spent its time living in water because its size would have been too cumbersome on land. The Titanoboa was not a dinosaur, though. It probably was able to grow so big because the planet was a lot warmer than it is now. A warmer environment is more favorable for cold-blooded snakes.

The anaconda today is recognized as the largest snake in existence. The largest anaconda ever found was 33 feet long, which is about the size of a telephone pole. This pales in comparison to the Titanoboa, which was five times larger than the average anaconda. An average anaconda tops out at about 15 feet long.

Summary of 5 Prehistoric Snakes

Here’s a recap of the five prehistoric snakes that we took a look at:

NumberSnakeTime of Existence
1TitanoboaLived about 60 million years ago
2Yurlunggur CamfieldensisLived 5 million to 30 million years ago
3Najash RionegrinaLived about 95 million years ago
4Coniophis PrecedensWent extinct around 65 million years ago
5Palaeophis ColossaeusWent extinct about 33 million years ago

The photo featured at the top of this post is © Michael Rosskothen/Shutterstock.com

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About the Author

Kristen Holder is a writer at A-Z Animals primarily covering topics related to history, travel, pets, and obscure scientific issues. Kristen has been writing professionally for 3 years, and she holds a Bachelor's Degree from the University of California, Riverside, which she obtained in 2009. After living in California, Washington, and Arizona, she is now a permanent resident of Iowa. Kristen loves to dote on her 3 cats, and she spends her free time coming up with adventures that allow her to explore her new home.

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