Give Now

A Moment of Science

When Snakes Had Four Legs

Scientists are still trying to figure out why ancient lizards evolved into snakes.

A copperhead snake (Agkistrodon contortrix)

What are you more afraid of: snakes or lizards? A lot of people are much more comfortable with lizards, despite their origins.

A fact that might be surprising to people who feel that way is that the ancestors of snakes are lizards. Scientists are still trying to figure out why those ancient lizards evolved into snakes.

Four-Legged Snakes

It’s a generally accepted fact that snakes evolved from lizards, but how they lost their legs is still controversial. Luckily, scientists recently discovered a fossil of a four‑legged snake that could give us some more clues.

Yes, you read that right, “four-legged snake.” Some of the reasons why the scientists classified it as snake rather than a lizard are: the skeleton has a long body, and not just a long tail; the jaw bones and teeth are snake‑like; and the skeleton shows hints that the animal had a single row of belly scales, which lizards don’t have.

These Hands Are For Prey

One really interesting observation the scientists made is that the hands and feet were capable of grasping things. The observation shows when snakes started slithering, they used their legs for something other than walking.

One thought was instead of just letting them hang uselessly on their bodies, the snakes may have used their “hands” and “feet” to grasp prey or mates.

Losing their legs was an adaptation to living underground in burrows. Extra limbs would just get in the way if you’re spending your life slithering through tunnels.

Sources And Further Reading:

Stay Connected

What is RSS? RSS makes it possible to subscribe to a website's updates instead of visiting it by delivering new posts to your RSS reader automatically. Choose to receive some or all of the updates from A Moment of Science:

Support for Indiana Public Media Comes From

About A Moment of Science

Search A Moment of Science