[Ol' Dan Tucker]

The various types of lungfish can breath air, and the African lungfish (aka Mudfish) can stay out of water for months and 'walk' on pectoral fins. There are also other types of air-breathing/land-'walking' fish eg the other types of lungfish, walking catfish, mudskippers, and bennies. I believe Bowfins can gulp air (although they do not 'walk' on land), and obviously there is the Northern Snakehead (which can breath air for several days, and while it doesn't use its fins for 'walking' it can wriggle from pond to pond).

What is the bone/joint structure present on the pectoral fins of the fish you named?

This one had the beginnings of upper arm, forearm and wrist joints on it's pectoral fins. That's the significant difference.

Embedded in the fin of Tiktaalik are bones that compare to the upper arm, forearm and primitive parts of the hand of land-living animals.

"Most of the major joints of the fin are functional in this fish," Shubin said. "The shoulder, elbow and even parts of the wrist are already there and working in ways similar to the earliest land-living animals."

[TitansAFC]

---"This one had the beginnings of upper arm, forearm and wrist joints on it's pectoral fins. That's the significant difference.

Embedded in the fin of Tiktaalik are bones that compare to the upper arm, forearm and primitive parts of the hand of land-living animals.

"Most of the major joints of the fin are functional in this fish," Shubin said. "The shoulder, elbow and even parts of the wrist are already there and working in ways similar to the earliest land-living animals."---

Wow. This is a great find! Now we know how animals went from living on land to living in the seas! Their forearms, shoulders, and wrists eventually gave way to fins!

A great discovery!