Tuesday, September 26, 2017

When Snakes Had Four Legs

When Snakes Had Four Legs
indianapublicmedia.org Sep 26, 2017 10:25 PM
A copperhead snake
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.

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