Snakes Lost Legs to Burrow

snakes
The common theory among scientists was that serpents evolved to adapt to watery environments and they no longer had a use for their legs. However, that theory may have been proven to not be true. International research scientists from the University of Edinburgh and the American Museum of Natural History, claim they have discovered the truth about why snakes have lost their legs; to hunt better. The result of this study was revealed in a press release given by the lead researcher, Hongyu Yi, from the university.

Due to the technology available today, Dr. Mark Norell, with the American Museum of Natural History, was able to use computer enhanced methods to examine the 90 million-year-old fossil of a D. patagonia, a six-foot-long relative of modern snakes. The researchers used CT scans in their study in order to gain a different perspective of the fossilized and modern reptiles.

The CT scans were then used, by scientists, to create 3D models of the serpent’s inner-ear. The inner-ear was examined and closely compared to that of the modern snakes and lizards. The inner-ear of the D. patagonia had large chambers so it would be able to hear low-frequency sounds. Scientists used this discovery to state that serpents had adapted to burrowing, by losing their legs.

It was also learned that the inner ear of the snake would evolve later, for subterranean life. These two changes were determined from the bone structure, which made it possible for serpents to hear predators and prey while they were underground. This is similar to the crown snake of today, which is able to feel vibrations enabling them to find predators and prey. However, there are several different species that live in burrows even today.

Scientists believed that the legs were a hindrance when burrowing. The slithering creatures eventually were able to grow simple small hind limbs and stopped growing front legs. Then the snake stopped growing legs entirely. Scientists believe this was for the purpose of digging into the ground. Although today, they do not all burrow.

According to scientists, the CT scans of the six-foot D. patagonia were proof it was one of the earliest and largest serpents that were able to burrow underground, making it the closest ancestor of today’s crown snake. Today those that live above ground or enjoy water life, do not have the same adaptations in their inner-ear.

Although snakes have always had the option to enjoy their activities on land or in water, according to Yi and Norell, ancient serpents, related to the crown snake, exclusively burrowed underground. This, however, has only filled in one gap in the evolution and ancestry of the serpent.

Hongyu stated that much information could be learned from the inner ear of a fossil, especially when the external bones are damaged. This new study has been published in Science Advances. Now, there is the hypothetical idea that all snakes evolved from an ancestral species that lived as a burrowing serpent.

By Jeanette Smith
(Edited by Cathy Milne)

Sources:

Outdoor Hub: Scientists: We Figured Out Why Snakes Lost Their Legs
New Historian: Snakes Lost Their Legs to Burrow Rather Than Swim
EurekAlert!: Mystery of How Snakes Lost Their Legs Solved by Reptile Fossil

Top Image Courtesy of FWC Fish and Wildlife Research Institute’s Photostream Flickr Page – Creative Commons License
Featured Image Courtesy of Troy Bell’s Flickr Page – Creative Commons License

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