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Analysis Reveals Prehistoric Snakes Were Nocturnal, Stealthy ... And Had Hind Legs

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New research reveals that the first snakes were forest-dwelling nocturnal predators with tiny back legs, ankles and toes.

For the study published in the BMC Evolutionary Biology journal on May 19, paleontologists from Yale University conducted a comprehensive analysis of the slithery reptile and found new insight into their origin and early history.

Although there are more than 3,400 species of snakes that live today, little is known about how and where today's snakes have emerged, but the discovery of new snake fossils and better quality specimens has now made it possible for researchers to conduct thorough analyses.

Study author Allison Hsiang, from Yale University, and colleagues analyzed the genes, fossils and anatomy of 73 different species of living and extinct snake and lizard, allowing them to reconstruct what the ancestral snake likely looked. The researchers identified the similarities and differences between these species and used these for creating a large family tree for snakes.

The researchers found evidence suggesting that the early snakes were stealthy hunters that thrived at night.

"We generated the first comprehensive reconstruction of what the ancestral snake was like," Hsiang said. "We infer that the most recent common ancestor of all snakes was a nocturnal, stealth-hunting predator targeting relatively large prey, and most likely would have lived in forested ecosystems in the Southern Hemisphere."

The study likewise suggests that the first snakes appeared 128 million years ago in a warm and forested part of the supercontinent Laurasia. It also showed that the creature did not have flexible jaws that characterize the snakes of today and, instead of burrowing, likely lived and hunted above ground. They also likely originated on land and not in water.

The nocturnal ways of the ancestral snakes were also passed on to many generations, so diurnal snakes did not show up until about 50 to 45 million years ago, when the Colubroidea family of snakes emerged in the scene. It is likely that the colder temperatures at night led the snakes to switch to daytime ways.

As to how the snakes lost their hind legs, these likely got in their way of slithering and gradually disappeared, albeit vestiges of these legs' existence still remain in some snakes such as pythons and boas. Other studies suggest that lizards and other reptiles with four legs evolved their legs from the simple form of the snake.

Photo: Matt Reinbold | Flickr

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