JOURNAL CLUB

摘要

During both inhalation and exhalation, the air in birds' lungs moves in just one direction, through small tubes. This is unusual: most animals move air tidally, in and out of dead-end gas-exchange structures. The question of when and how the avian breathing mechanism evolved is interesting to palaeontologists like me who study these unusual features.rnTraditionally, the avian pattern of one-way breathing has been thought to depend on special accessory air sacs that work similarly to bellows. Largely because they don't have these air sacs, alligators have always been presumed to be tidal breathers.