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Study: Here’s how snakes lost their legs

Ashley May
USA TODAY

Can you think of anything more terrifying than a snake with legs?

A study out of the University of Florida says snakes had legs 150 million years ago, but no longer do because of deleted DNA.

Early fossils lead some scientists to believe snakes once had legs (some say two and others say four), which begs the question: How did they lose them?

Scientists of the study, published in Current Biology, said the Sonic hedgehog (yup, like the video game) gene, still present in python embryos, spurs the growth of legs. But the gene is weak in modern snakes because supporting DNA is no longer in the reptile's system, according to the study. So, python legs are truncated — pythons and some other snakes have two bumps on each side of their pelvis.

Because the Sonic hedgehog gene is still sticking around, co-author and molecular genetics professor Martin Cohn told NPR there's a possibility snakes could grow full legs again — "there's already a remarkable degree of limb development that happens in the embryo and if you just retained those embryonic structures and allowed them to complete skeletal development, you have legs."

Last year, researchers at the University of Edinburgh looked at CT scans of a 90 million-year-old reptile fossil to determine snakes lost their legs to hunt in burrows. Previously, researchers believed snakes evolved without legs to survive in the water.

University of Florida scientists studied pythons' limb development.

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