Fig. 7

Relationship between the extents of MB and pneumaticity skeletal distributions. Predictions of MB skeletal distribution in birds with different body-sizes and ecologies if the inverse relationship between the skeletal distributions of MB and pneumaticity is verified (a). Diagram highlighting that our results support our predictions (b). Five selected specimens illustrate that MB skeletal distribution is relatively limited in large (e.g. Rhea americana YPM-148246) and active flying birds (e.g. Bubo virginianus CM-S5027), but extensive in small (Phaethornis superciliosus CM-S8888; Lonchura punctulata TMM-M6977) and plunge-diving birds (Sterna dougallii CM-S7995). Specific body mass data for adult females were gathered from [49]. The skeletal scheme used here is representative of the general bird skeleton depicting all considered elements, regardless of the species