[Nathan Zachary]

yeah, sure. and the fossil record is where?
In case you've never gutted a fish, a air bladder is quite a bit different from lung material, and is located in the intestinal tract. Picture how that fish would 'breathe', LoL!

[Junior]

It doesn't matter where it resides in a fish. During the developmental process the tissue that differentiates to become a swim bladder in a fish develops into lungs in terrestrial vertebrates.

Evolution is not based solely on the fossil record. There is the genetic record, and the embryonic developmental record that also contribute evidence.

[b_sharp]

"In case you've never gutted a fish, a air bladder is quite a bit different from lung material, and is located in the intestinal tract. Picture how that fish would 'breathe', LoL!

Lungfish, and Snakeheads both have methods to breathe air directly by using what can only be described as lungs or lung precursors. Both lungs and float bladders are modified sections of the esophageal tube.

If you are demanding that modern lung tissue be the only standard for lungs you are being closed minded and religiously ignoring alternatives. Besides, it's nothing but the genetic fallacy in action.