The lungs of ancestral, land-based vertebrates may have had multiple chambers rather than just one, as was believed.

Markus Lambertz at the University of Bonn in Germany and his colleagues studied lung samples from 73 species of amniotes, which include mammals, birds and reptiles. They also looked at lung development in embryos of a gecko, Paroedura picta, which has single-chambered lungs. They found that all multi-chambered lungs shared key anatomical features, such as branching of the arteries. These features were present even in the single-chambered lungs of lizards and snakes, and in the embryonic gecko lung.

Ancestral amniotes evolved multi-chambered lungs as they shifted to life on land, the authors say. Some, however, may have later developed single-chambered lungs as they evolved into smaller creatures to maximize air space in the lungs, the team adds.

Biol. Lett. 11, 20140848 (2015)