Why on Earth would something develop wings to fly? It's not like there would have been anything in the environment that necessitated that for survival. I'm also curious about the development of lungs. They would need to be a minimum size for a creature to depend on them for survival. How could they have developed slowly when they weren't even useful at first. There'd be no purpose for them.
Evolution is driven not by what is "necessitated", but by what is an advantage. As for the selective pressures which would drive it, see my earlier post (the one with all the bird transitional fossil pictures.
I'm also curious about the development of lungs. They would need to be a minimum size for a creature to depend on them for survival. How could they have developed slowly when they weren't even useful at first. There'd be no purpose for them.
You shifted gears in the middle of your paragraph, and didn't even notice. Yes, they would need to be a minimum size (or more accurately, functionality) for a creature to DEPEND on them. However, in your next sentence you claim they wouldn't "even be useful" -- this is a shift. Proto lungs would be *useful*, even if they were not yet sufficient to fully *depend* on yet (as a sole means of acquiring oxygen.
The answer was actually provided by Darwin in his 1859 book (and was based on yet still earlier evidence), and has been confirmed and reconfirmed by fossil and DNA research since then.
The answer is that early lungs developed in animals that already were relying on some *other* primary means of acquiring oxygen. Lungs developed in some lineages of early fish, as an *auxiliary* to the gills which were the primary oxygen system. So there's the answer to your puzzle -- early lungs were an *assist* to the gills, not a system that had to develop entirely from scratch all the way to full functionality before the animal could breath in the first place. So even a barely functional proto-lung would still be useful, and the animal would still be able to survive (because it didn't *depend* solely on its lungs for its survival).
The fish lineage which eventually evolved into amphibians evolved the ability to store fresh air in its swim bladder (which was already an air sac used for floation) in the manner of a "scuba tank", which would allow it to have a source of oxygen even when venturing into brackish water where the gills began to have trouble getting enough oxygen. The "lungs" were a supplement. Over time, they became more sophisticated and capable in this function, and their ability to exchange the oxygen they contained with the bloodstream grew in efficiency, until eventually the "lungs" became worthy of their name, and became something which the animal could use on its own even when the gills were unable to carry on (as in totally brackish water, or when crawling across land in search of new bodies of water, as in modern mudskippers or lungfish).
The mistake that many people make when trying to picture evolutionary developments of modern organs or systems is that they try to picture they arising *in* modern organisms (you probably tried to imagine lungs appearing in an early mammal or somesuch, right?) Instead, it's often the case that modern organs evolved in very different animals or different circumstances, when other systems or environments were "carrying the load" that the organ *eventually* (but not in the beginning) became the primary carrier of.
Why are there flying squirrels? (Yes, you asked about feathered wings, but I will get there via squirrels.)
Because it is safer to glide, tree-to-tree, than to scamper down to the ground and risk death just to get to another tree. When a mutation occurs with a squirrel having skin flaps allowing it to get some lift and glide between trees, that genetic adaptation is passed along to its offspring. All are more likely to survive than a squirrel running a terrestrial gauntlet of predators.
Squirrels haven’t developed wings but they use the extensive skin flaps between foreleg and rear leg, right and left, to glide between trees.
The same survival need probably provided the opportunity for a mutation, which normally would not be of any import, to become the impetus for winged dinosaurs.
There are fossils of winged dinosaurs that used skin, similiar to squirrels, instead of feathers. These creatures were quite large and ungainly on land, but from where the fossils have been found, they flew huge distances across oceans, breeding in one geographical area (fossil remains of nests) and traveling to other continents for feeding, a migratory pattern seen today in many animals.
Mind, you asked about why feathers exist. Feathers seem to be an adaption to cold weather, a mutation of scales (feathers and scales are made from the same material as our fingernails), and functioned as insulation to trap air and maintain body warmth. Later, insulating feathers developed into stiff feathers beneficial to flight, and it may just be luck for those creatures, or the intervention of God, that the adaptation occurred.
Yes, I believe in God. I also believe that the laws governing the functioning of our universe come from God, and that scientists, knowing or unknowing, are discovering those laws.