Snakes lost their legs when they evolved and started living and hunting in burrows, a team of scientists from Scotland and the United States says, after analyzing a 90-million-year old fossilized skull. Today, many snakes still hunt and live in burrows. Scientists from the University of Edinburgh, and the American Museum of Natural History, explained that snakes didn’t lose their legs to enable them to survive in the ocean, according to CT scans of fossils. The inner ear of Dinilysia patagonica (a 2 m long reptile that is closely related to snakes) was examined by Dr. Hongyu Yi from Edinburgh University’s School of GeoSciences and Dr. Mark Norell of the American Museum of Natural History using CT scans. (A) D. patagonica’s braincase. It shows the correct otic area in a lateral view. B) An X-ray CT scan of MACNRN 1014. The inner ear has been highlighted in blue. D. patagonica’s bony inner ear. FO, foramen ovale; LR, lagenar recess; SC, semicircular canal; V, vestibule. Scale bars, 5 mm. Image: Science Advances. The animal’s balance and hearing were controlled by the cavities and bony canals in its inner ear. Three-dimensional models of Drs. To compare modern snakes and lizards’ inner ears with fossils, Yi and Norell developed 3-D virtual models. Researchers discovered a unique structure in the inner ears of active burrowing animals, likely helping them to spot predators and prey. Modern snakes living above water or on the ground do not have this structure. Scientists will be able to fill in gaps in our understanding of how snakes evolved, according to the researchers. The authors confirm that Dinilysia Patagonica, a burrowing snake, is the largest known. The authors also discovered clues to the possible species that all modern snakes descend from, which is likely a burrower. D. patagonica’s total body weight is larger than snakes of today. Loxocemus Bicolor, a burrowing snake that can grow up to 160 m in size, is the biggest. Leptotyphlops calae, the smallest known snake is currently in existence. Image: Science Advances. Dr. Hongyu Yi stated that although scientists have long wondered how snakes lose their legs, it appears to be due to their ability at burrowing. The fossils’ inner ears can provide a wealth of information and can be used to determine if the fossils have suffered damage or are fragile. Dr. Norell stated that this discovery was impossible a decade ago. CT scanning has changed how we study old animals. The Royal Society supported the study. We are hopeful that similar research will shed light on how other species evolved. Citation: Hongyu Yi, Mark A. Norell. Science Advances Vol. 1, no. 10, e1500743. 27 Nov 2015. DOI: 10.1126/sciadv. 1500743.
Snakes lost legs to live and hunt in burrows, new study suggests
