[lynguist]

That’s exactly right - I want to give another example: Squamates want to develop a legless body. Snakes have emerges, but there are also legless geckos, legless lizards etc, etc.

The thing is that normally the change happens in the speciesation first and then these traits are used for something distinctive - dinosaurs grew feathers first, and then used them for flight. Humans grew intelligence first, and then used it for civilization. The resource has to be already there to be used. The resource will not be developed by evolution. The lungfish already had limbs and joints (while living purely aquatically), thus it could use it to walk outside the water.