title: The burrowing origin of modern snakes.
abstract: Modern snakes probably originated as habitat specialists, but it controversial unclear whether they were ancestrally terrestrial burrowers or marine swimmers. We used x-ray virtual models of the inner ear to predict the habit of Dinilysia patagonica, a stem snake closely related to the origin of modern snakes. Previous work has shown that modern snakes perceive substrate vibrations via their inner ear. Our data show that D. patagonica and modern burrowing squamates share a unique spherical vestibule in the inner ear, as compared with swimmers and habitat generalists. We built predictive models for snake habit based on their vestibular shape, which estimated D. patagonica and the hypothetical ancestor of crown snakes as burrowers with high probabilities. This study provides an extensive comparative data set to test fossoriality quantitatively in stem snakes, and it shows that burrowing was predominant in the lineages leading to modern crown snakes.
authors.affiliation: School of Geosciences, University of Edinburgh, James Hutton Road, Edinburgh EH9 3FE, UK. ; Division of Paleontology, American Museum of Natural History, Central Park West and 79th Street, New York, NY 10024, USA.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Yi
authors.affiliation: Division of Paleontology, American Museum of Natural History, Central Park West and 79th Street, New York, NY 10024, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Norell
keywords: HRCT; ancestral state reconstructions; bony labyrinth; crown snake origin; functional morphology; geometric morphometrics; inner ear; virtual model building