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Ancient snakes had tiny little hind legs and hunted alongside dinosaurs

An artist's rendering of an ancient snake, with tiny hind limbs. (Julius T. Csotonyi)

The first snakes originated on land, where they hunted at night in the lush forests of the Early Cretaceous period about 128 million years ago, according to a comprehensive new look at the early ancestors of the notorious reptiles. Oh, and they had tiny little hind legs, complete with itty-bitty ankles and toes.

The new study from a team of Yale paleontologists is "the first comprehensive reconstruction of what the ancestral snake was like," Allison Hsiang, lead author of the study, said in a statement. The study was published on Tuesday in the journal BMC Evolutionary Biology.

[Museum fossil find pushes snake origins back by 65 million years]

Experts have long debated the details of how, and where, the first snakes lived. The Yale team hopes that their reconstruction, which relies on a plethora of new, more complete fossils recently uncovered, will help to settle some of those questions. Today, there are some 3,400 different snake species roaming the earth.

Daniel Field, a co-author of the study, said the findings settle at least two major "longstanding debates" about the origins of snakes. "Our analyses suggest that the most recent common ancestor of all living snakes would have already lost its forelimbs, but would still have had tiny hind limbs, with complete ankles and toes," he said in a statement. "It would have first evolved on land, instead of in the sea."

These ancient snakes hunted at night and targeted the small vertebrates (including nocturnal mammals) that lived in the forest. They consumed their prey whole just like today's snakes. However, the Yale researchers believe, the first snakes couldn't manage to eat anything bigger than their own heads. And early snakes didn't constrict their prey like some snakes can today. Instead, they grabbed it with tiny sharp teeth.

Both the dinosaurs and the earliest snakes experienced a catastrophic extinction event at the end of the Mesozoic period. But unlike the dinos, the researchers believe snakes flourished. In fact, snakes may have that die-off to thank for their success.

[Did a massive volcanic eruption in India kill off the dinosaurs?]

The ancestors of snakes slithering around today "were able to take advantage of the relatively empty landscape left behind by the dinosaurs," Field and Hsiang wrote in a blog post explaining their findings. Like mammals, the early snakes found themselves living in a world where the dominant animals were suddenly no longer around, leaving tons of ecological niches open for the taking.

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