[metmom]

How would an animal with half-developed wings slowing it down and holding it back and getting tangled in the grass beat out an animal who had the advantage of no burdensome half-wings?

You'll get ganged up on for that one. I asked a similar question about limbs that would be evolving to flippers for use in water and just got mocked for that one.

I never did get a decent explanation of how a limb that was halfway between leg and flipper could be of decent use as either.

A leg that was half flipper, wouldn't be good for running or climbing. A fin or flipper that was half leg wouldn't be as efficient for swimming.

In either case, it would slow down the creature to be caught in whatever medium it was in. The creature couldn't run fast enough to elude fully legged land creatures, and couldn't swim fast enough to escape fully finned and streamlined water creatures.

[ColdWater]

[PapaBear3625]

The otter spends a lot of time in the water, and has evolved a webbed foot:

which is good for swimming, while still allowing it to walk on land fairly well.

A mammal which spends much more time in the water, like the seal:

has much more prounced webbing on its limbs.

And you finally get to full fins like dolphins have.

[<1/1,000,000th%]

Maybe they were predatory fish.