The Principle of Contingent Causation: The Impossibility of Infinite Regress.

[arewethereyet]

They don't need them.  They chew up rocks to create lighter than air gasses, and they hold that in a special bladder.  That's why they live in caves.  Those ridges along it's back along with the tail provide directional thrust and inertial control.  To decrease in altitude, or if they're annoyed, they belch flame, expelling the flammable mixture.

You have thought about this too much.