No one is really sure where snakes came from. We know they evolved from lizards and appeared sometime in the Middle Jurassic (~167 million years ago), but it’s unclear exactly which group of lizards they diverged from and why they ultimately lost their legs.
This ‘Great Snake Debate’ isn’t helped by the fact that these delicate animals don’t fossilise very well and have only left us scant remains to study. There isn’t much to glean from genetic data either, which supports two conflicting evolutionary hypotheses: one where snakes evolved on land, and one where they evolved in water.
While their origins may be a bit of a mystery, we do know that snakes rapidly diversified once they gained an ecological foothold, evolving into thousands of different forms. From giants longer than a double-decker bus to dwarfs with functioning limbs, here are 10 of the most remarkable snakes from prehistory…
Eophis - the oldest snake ever found
Lived ~167 million years ago
Described in 2015 and dated to the Bathonian Age of the Middle Jurassic (~167 million years ago), Eophis is the oldest snake currently known to science. It was found in a quarry near Oxford and lived at the same time that Megalosaurus, a 6m-long, meat-eating dinosaur, also roamed this part of southern England.
Eophis was far from a giant. Measuring just 25cm, it’s the smallest snake on this list and comparable in size to modern threadsnakes - a group that includes the smallest known snake species, the 10cm-long Barbados threadsnake. Eophis is thought to have lived in swamps, hunting tiny fish, insects, and tadpoles. It’s also believed it had tiny hind limbs, like many other ancient snakes.
Prior to 2015, the oldest known fossil snakes were ~100 million years old. The discovery of Eophis extended the known geological range of snakes by more than 60 million years and suggested they may have originated at a similar time to most other major groups of scaly reptiles.
Haasiophis - the sea snake with hind limbs
Lived 99.6-93.5 million years ago
Not all snakes live on land; even today there are more than 70 species that live exclusively in water. In the Late Cretaceous, the shallow seas that once covered much of the Middle East were home to several sea snakes, although unlike today’s slithery seafarers they had hind limbs.
Haasiophis was one of these snakes. It was 90cm-long and it’s thought it swam just like an eel does, whipping its body from side to side in an effort to generate forward momentum. Its hind limbs were small yet fully developed, with hip, knee, and ankle joints. What Haasiophis and its close cousin Pachyrhachis, another limbed sea snake, used their little legs for is unknown.
It’s also unclear why these sea snakes had hind limbs. There are currently two competing theories - the first suggesting they were evolutionary leftovers from their time as four-legged lizards, and the second suggesting they actually regained them from legless ancestors.
Titanoboa - the largest snake ever found
Lived 60-58 million years ago
Titanoboa was first discovered in the early 2000s in northeastern Colombia, but it wasn’t until 2009 that it was officially described and crowned the largest snake ever found at ~13m in length, taking the title from the previous record-holder Gigantophis (~11m).
Titanoboa lived during the Palaeocene (~60-58 million years ago) and just after the non-avian dinosaurs faced extinction at the end of the Cretaceous. It’s widely considered the largest terrestrial vertebrate of its time and similar in length to the biggest T.rexes.
Like a lot of other prehistoric snakes, Titanoboa wasn’t venomous and instead hunted like today’s boas do, constricting prey with their large, muscular bodies. It lived in wet tropical forests with large river systems and fed on huge freshwater fish like arapaima.
How Titanoboa was able to grow so large, and why we don’t have any similarly sized snakes today, can be explained by the climate of the Paleocene. This was a particularly warm period, when annual temperatures in northeastern Colombia averaged 32–33°C. These balmy temperatures sped up the metabolism of cold-blooded creatures, like Titanoboa, and allowed them to grow to obscene sizes.
Vasuki - the king of the serpents
Lived ~47 million years ago
Named after the divine Hindu serpent of the same name, Vasuki was described as recently as April, 2024, from 27 well-preserved fossil vertebrae found in a lignite mine in India’s Gujarat state. From these vertebrae, researchers have estimated Vasuki’s total body length at 11-15m. This upper estimate would make Vasuki larger than the largest snake ever, Titanoboa, but due to some discrepancies in how the lengths of the two giants were estimated, it’s too early to crown a new ‘largest snake’.
Unlike Titanoboa, Vasuki wasn’t an aquatic predator. Instead, its vertebrae suggest it was semi-aquatic and able to hunt both on land and in water. It also probably used its huge body to squeeze and suffocate its prey, just like Titanoboa did.
Vasuki was a madtsoiid snake that lived in India around 47 million years ago and flourished in the forested swamps that once covered the now arid Kutch district of Gujarat. It’s believed it may have preyed upon the turtles, crocodilians, and early whales that also lived in these swampy environments.
Najash - the snake that rewrote history
Lived ~90 million years ago
Until the discovery of Najash in the early 2000s, some palaeontologists subscribed to the idea that snakes evolved from large marine reptiles known as mosasaurs. This theory was based on the fact that some of the earliest snakes known at the time, sea snakes found in the Middle East, had mosasaur-like jaws and small hind limbs. However, Najash - a medium-sized, land-dwelling snake from South America that also possessed hind limbs and lived at a similar time - quickly cast doubt on this theory and brought consensus towards a terrestrial origin for snakes.
It’s widely thought that snakes started to lose their limbs just after they diverged from lizards some 170 million years ago, but Najash proves they retained their hind limbs for at least 80 million years. This suggests limbed snakes were not just a transitory phase, as was previously thought, and that perhaps there were some benefits to be had from carrying around stumpy appendages. Some living snakes, such as boas and pythons, still have vestigial hindlimbs (known as spurs) that they’ve repurposed for clasping and tickling their mates while breeding.
Rukwanyoka - the snake that revolutionised venom
Lived ~25 million years ago
Of the roughly 600 species of venomous snakes alive today, around half of them are elapids. This group includes some of the world’s deadliest snakes, such as cobras and black mambas.
The earliest known elapid fossils are dated to 25 million years ago and belong to a snake known as Rukwanyoka. Rukwanyoka didn’t invent venom (it’s believed venom was an ancient adaptation that the four-legged ancestors of snakes may have even possessed), but it’s thought that Rukwanyoka and its elapid descendants did turn it into a potent weapon.
Unlike other types of snake venom, elapid venom is neurotoxic and specially designed to disrupt basic bodily functions, such as movement and breathing. What’s more, this venom is universal and can bind to neuroreceptors found in all vertebrates, from fish to humans and everything in between.
Rukwanyoka lived in East Africa at a time when modern snake assemblages first emerged. It’s thought this overturn may have been sparked by climate change, with new environmental conditions favouring active, venomous snakes rather than ambush specialists.
Wonambi - the last of the mega snakes
Lived 23 million to 12,000 years ago
Wonambi is one of 17 different types of madtsoiid snakes known to science and the last of a long lineage that stretched all the way from the Late Cretaceous (~98 million years ago) to the Late Pleistocene (~12,000 years ago). These snakes ranged dramatically in size, from less than 1m to maybe more than 15m in the case of the recently described madtsoiid, Vasuki.
Wonambi was roughly 6m-long and, like other madtsoiids, specialised in the art of ambushing and constricting its prey. It lived in the cool and arid regions of Australia, dwelling beside water holes where it would ambush kangaroos, wallabies, and other medium-sized mammals.
While most other madtsoiids became extinct during the Eocene (~56-34 million years ago), Wonambi survived in Australia right up until 12,000 years ago. Some researchers think humans, who arrived in Australia ~50,000 years ago, may be to blame for Wonambi’s extinction. It’s thought Wonambi may have also inspired the Rainbow Serpent of Aboriginal Australian mythology.
Sanajeh - the dinosaur-eating snake
Lived ~68 million years ago
Snakes are known for their sneakiness and Sanajeh may have been one of the sneakiest, able to slither into the nests of some of the largest dinosaurs that ever lived and snatch their young.
This 3.5m-long madtsoiid snake lived during the Late Cretaceous (~68 million years ago) and was described in 2010 from an incredibly preserved fossil found in western India. This fossil preserves the body and skull of a Sanajeh wrapped around a crushed egg and laid next to a 50cm-long titanosaur hatchling. From the same site, researchers have found another Sanajeh associated with another clutch of eggs, suggesting this snake had a particular taste for baby dinosaurs.
Sanajeh’s name means ‘ancient gape’, which is ironic considering it couldn’t open its mouth quite as wide as modern snakes can do. Nevertheless, studies of its skull have shown that it was capable of swallowing the hatchling it was found alongside, and may have even deliberately crushed eggs to get at the easy meals they held.
Laophis - the giant Greek viper
Lived ~4 million years ago
At roughly 4m in length and weighing in at nearly 26kg, Laophis is widely regarded as the largest venomous snake that ever lived.
What makes this giant snake particularly interesting is that it lived in Greece around 4 million years ago and during a time when the climate was cool and the environment was dominated by grasslands. Most large snakes, both extant and extinct, come from tropical environments where warm temperatures boost their metabolisms and allow them to grow incredibly large. It’s unclear how, in a cooler climate, Laophis kept its metabolism going to support its size. Those who study this snake suggest it may have had some unique aspects to its biology, but more evidence is needed to find out what these adaptations may have been.
Laophis lived alongside grassland mammals and is thought to have preyed on anything from rodents to small deer. Like its modern-day relative the Gaboon viper, Laophis may have hunted its prey by lying in wait before striking, injecting a lethal dose of venom, and holding on until they died.
Palaeophis - the bus-sized sea snake
Lived ~56-34 million years ago
Rivalling Titanoboa in length at 12.3m, the aptly named Palaeophis colossaeus is considered one of the largest snakes that ever lived and by far the largest sea snake. There were several species of Palaeophis, ranging from the 1m-long Palaeophis casei to the giant Palaeophis colossaeus.
This group of snakes lived during the Eocene (~56-34 million years ago) and stalked the warm, shallow seas that once covered much of Europe and North Africa. It’s unclear what the largest amongst them ate, as no skull fossils have been found, but comparisons with other snakes have suggested they may have been capable of eating anything from large fish to small whales.
Some more advanced species of Palaeophis had broad and robust vertebrae that made them particularly strong swimmers and well adapted to life underwater. These vertebrae also show signs of having had lots of blood vessels run through them, suggesting Palaeophis had faster metabolisms than other snakes. This has led some researchers to hypothesise that they may have been on their way to becoming ‘warm-blooded’.
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