A fossil animal locked in Lebanese limestone has been shown to be an extremely precious discovery - a snake with two legs.

Scientists have only a handful of specimens that illustrate the evolutionary narrative that goes from ancient lizard to limbless modern serpent.

Researchers at the European Light Source (ESRF) in Grenoble, France, used intense X-rays to confirm that a creature imprinted on a rock, and with one visible leg, had another appendage buried just under the surface of the slab.

"We were sure he had two legs but it was great to see it, and we hope to find other characteristics that we couldn't see on the other limb," said Alexandra Houssaye from the National Museum of Natural History, Paris.

The 85cm-long (33in) creature, known as Eupodophis descouensi, comes from the Late Cretaceous, about 92 million years ago.

Unearthed near the village of al-Nammoura, it was originally described in 2000.