Scientists in America and Scotland concluded that the legs of the snakes were lost to enable them to live in burrows and hunt more efficiently. Although snakes can live in many different environments today, most still hunt and live in burrows. Science published the findings of scientists from the American Museum of Natural History (AMNH) and University of Edinburgh. The scientists compared CT scan images to confirm that the snakes did not have to lose their legs and arms to adapt to living in water. Snakes, despite not having legs, are excellent hunters. The American Museum of Natural History’s Mark Norell is a paleontologist, molecular geneticist, and Dr. Hongyu Yi at Edinburgh University’s School of GeoSciences used CT scans for a detailed examination of the inner ear of the 2-metre-long snake, closely related to the modern Dinilysia Patagonica. As with modern burrowing snakes, Dinilysia patagonica had its inner ear’s bony cavities as well as canals. To compare fossils’ inner ears with today’s snakes or lizards, Dr. Yi created detailed 3-D models and Dr. Norell made virtual 3-dimensional models. Researchers discovered a distinct structure in the inner ears of active burrowing animals. This likely helps them to identify prey and predators. The structure is not found in any snakes that are either above or below ground. Scientists believe that their discoveries will help scientists in filling in gaps in our understanding of how snake evolution occurred. (A) Dinilysia patagonica braincase showing right otic area – lateral view. B) An X-ray CT scan of MACNRN 1014 showing the inner ear highlighted in blue. Dinilysia patagonica’s bony inner ear. FO, foramen ovale; LR, lagenar recess; SC, semicircular canal; V, vestibule. Scale bars, 5 mm. (Credit to Science Advances). The authors have confirmed that Dinilysia Patagonica is the largest known burrowing snake. This study revealed that snakes had a common ancestor, which was most likely a burrower. The authors also provided clues about the species of hypothetical origin from which all current snakes descend – this being Dinilysia patagonica. Dr. Hongyu Yi explained that although scientists have long wondered how snakes lose their legs, it appears this was due to their ability at burrowing. Inner ears can provide a wealth of information and can be very helpful when fossils’ exteriors are damaged or fragile. Dr. Norell said that this discovery wouldn’t have been possible 10 years ago. CT scanning has changed the way we study old animals. Similar studies are possible to shed more light on evolution, such as lizards, turtles, and crocodiles. The Royal Society also supported this study. Refer to: Mark A. Norell, Hongyu Yi. Science Advances. Nov 27, 2015. DOI: 10.1126/sciadv. 1500743.
