>>13598420>I just blatantly assumed, why are you asking?Because some fish alive today have lungs, which are modified swim bladders.
So it's not unreasonable to think tiktaalik had some lung-like organ allowing it to breathe atmospheric oxygen.
Especially since human lungs secrete a liquid to allow gaseous oxygen to dissolve, and then diffuse into the blood.
I'm not a pulmonary specialist, but it seems to be one of the easiest organs to evolve:
- large surface area
- surfactant
- rich blood supply
- short distance between surfactant and blood
