Are Snakes With Legs a Real Thing?

Snakes evolved from ancient lizards, and many scientists believe that their limbless bodies were an adaptation to help them burrow or swim more efficiently.

Early snakes likely had legs, but as they adapted to new environments — like burrowing underground or slithering through dense vegetation — their limbs became less useful. Over millions of years, these legs shrank and eventually disappeared, giving snakes their long, slender, limbless body that we recognize today.

Some snakes, especially species that lived in the water like sea snakes, evolved to be sleek and smooth, perfect for gliding through water.

On land, snakes became efficient predators, able to squeeze into tight spaces to catch prey. Their vestigial legs — the remnants of their old limbs — are still visible in a few species today, but they’re nonfunctional.

One of the most exciting pieces of evidence for four-legged snakes comes from fossil snakes. In 2015, scientists discovered a fossil snake from South America that had tiny legs.

This four-legged snake, named Tetrapodophis amplectus, lived around 120 million years ago and had well-developed fore and hind legs. The discovery, published by a scientist from the University of Portsmouth, helped confirm that ancient snakes once had fully functional legs.

Over time, these legs became smaller and less useful, likely due to changes in their environment or the way they hunted. Eventually, these legs became vestigial, meaning they shrank into small, nonfunctional structures that no longer served a purpose.

More Fossil Evidence

Another important fossil snake is Najash rionegrina, found in Patagonia. This species had well-developed hind legs and lived around 90 million years ago, further showing that snakes slowly lost their legs as they evolved from lizard-like ancestors.

The fossil record of early snakes gives us a look into how these legged reptiles transformed into the slithering creatures we know today.

Scientists have found that genetic mutations responsible for limb development were gradually switched off over millions of years, causing snakes to lose their limbs. Besides the fossil record, scientists have also used developmental biology to study the role of genes in the natural history of snakes.

In 2016, geneticists at the Lawrence Berkeley National Laboratory discovered that, by swapping certain parts of snake genes into mouse embryos, they could alter the embryonic development, significantly truncating the developments of the four legs found in the mammals.

This discovery suggests that snakes once grew legs, but over time, genetic changes — likely combined with natural selection — led to their back and front legs being phased out.

Not quite. Today's snakes don't have fully formed legs, but some, like the reticulated python, still carry traces of their limb-filled past. If you look closely at pythons and boas, you'll see small spurs near their tails; these are vestigial legs, tiny remnants of what were once full-sized limbs.

As for fully functioning, four-legged snakes in today’s world? Sorry, folks, but no modern snakes have true, working legs. However, their evolutionary journey from limbed lizards to limbless body is a remarkable example of how species adapt to their environment over time.

We created this article in conjunction with AI technology, then made sure it was edited and fact-checked by a HowStuffWorks editor.