Adaptations in the Nasal Passages for Sand Burrowing in the Saurian Genus Uma

摘要: Members of the iguanid genus Uma possess looped, U-shaped nasal passages which in structure and functioning prevent inspiration sand particles during subsurface respiration. The following factors are involved exclusion elimination particles: (1) interfere with one another as they drawn toward external naris inspiration. There is a tendency formation grill interlocking fragments obstruct other loose grains. (2) When lies buried vestibule situated at an angle to horizontal. must be up approach tube against pull gravity before reaching principal cavity. (3) Sand grains adhere walls tend impede movement free (4) Under conditions respiration valve reduces aperture narrow crescentic slit, limiting particles. (5) postulated reduction diam...