Scientists Suggest Snakes Evolved From Land-Lubber Lizards

By Patrick Morgan | February 7, 2011 6:21 pm

Ask a group of snake researchers whether our modern snakes evolved from land-loving or ocean-loving lizards, and you’re likely to start a heated argument. But the days of snake-origin squabbles may be coming to a close–researchers have created the first 3-D images of snake fossils and have discovered that their legs are more akin to the legs of land-dwelling lizards than they are to the ocean-dwelling kind.

The researchers studied a 95-million-year-old fossilized snake called Eupodophis descouensi that was found in present-day Lebanon. Published in the Journal of Vertebrate Paleontology, the scientists used a novel 3-D imaging technique called synchrotron-radiation computed laminography:

“Synchrotrons are enormous machines and allow us to see microscopic details in fossils invisible to any other techniques without damage to these invaluable specimens,” said co-author Paul Tafforeau from the European Synchrotron Radiation Facility. [Discovery News]

According to lead researcher Alexandra Houssaye, their results were surprising:

The scanning revealed a hidden leg, bent at the knee but lacking foot and toe bones. The setup of the bones is similar to that of terrestrial lizards, Houssaye said, adding that one study couldn’t settle the “land ancestor versus water ancestor” debate. However, she said, the anatomy of the bones suggests that evolution took snakes’ legs not by altering the way they grew. Instead, Houssaye said, it looks as though the limbs grew either slower or for a shorter period of time. [Live Science]

The researchers suggest that the legs may have interfered with the burrowing habits of a terrestrial lizard species, giving animals that reduced their legs an adaptive advantage. Even though this scanning study does support the theory that modern snakes evolved from the land-dwelling lizards, the jury is still out as to which snakes species is the great grand-daddy:

“The question of snake origin should not be resolved in the next 10 years,” Houssaye said…. She is, however, hopeful that all of the separate teams working on this puzzle can one day pinpoint what species was the common ancestor of all snakes. [Discovery News]

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