X-rays allowed scientists to find a missing hind limb in a fossil snake. Although she is severely underdeveloped, her detailed analysis has allowed scientists to clarify the question of the origin of snakes. And add proof that snakes evolved from terrestrial reptiles
A new technology based on the use of X-rays has allowed a team of scientists led by Dr. Alexandra Houssaye of the Natural History Museum (Paris) to discover and study in detail the structure of the pelvic girdle and hind limb in the fossil snake Eupodophis descouensi. According to scientists, this will help them solve the question of the origin of snakes - a question over which paleontologists have been racking their brains for many years. The fact is that it is not known whether the snakes separated from the reptiles living in the water, or from the group living on land.
Snake leg in 3D
On the basis of layer-by-layer scanning, the scientists carried out a detailed 3D reconstruction of the structure of the hind limb bones of Eupodophis descouensi and came to the conclusion that they most of all resemble the structure of the hind limbs of terrestrial reptiles.
The complexity of the study was that the fossil Eupodophis descouensi had only one limb on the surface, while the other, as suggested by Usse, was hidden in the rock mass. The researchers were not mistaken, and using X-rays, they were able to find the missing leg.
“Currently, there are only three fossil snakes with preserved hind limbs and lost forelimbs. They belong to three different groups - Haasiophis, Pachyophis, and Eupodophis. The limbs of other known fossil groups of snakes have not been preserved. Nevertheless, based on their anatomical structure, it is believed that they did have limbs,”the authors write in their article, which will be published in the Journal of Vertebrate Paleontology.
Intermediate stage
The fossil snake Eupodophis descouensi, which came to the attention of scientists, was discovered ten years ago in rocks that are 95 million years old in the sediments of Al Nammoura in Lebanon. “The snake's body reached 50 centimeters in length, and the hind limbs were heavily reduced, they were attached to the pelvic girdle and were no more than two centimeters long,” the researchers say.
According to scientists, this Eupodophis descouensi specimen is very successful. It represents a rare intermediate stage in the evolution of reptiles. “The study of Eupodophis descouensi helped us understand how snakes gradually lost their limbs during evolution. We believe that this loss did not occur as a result of any anatomical changes in the structure of the bones, but, most likely, was associated with a shortened growth period,”says Ussé.