Maybe a little naïveté, but mostly just some speculation of a fantastic nature. No telling what sort of extraterrestrial life forms may have evolved elsewhere.

Like that Icarus dude, but with the wings being actual biological appendages.

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I must concede a partial exception: elephants' trunks. But an elephant has only one trunk, a single one in front, and not one on each side of the body that extends from the spinal column. Furthermore, elephant trunks are extended noses that are all soft tissue.

It would be interesting to know the precursors to spiders, centipedes and millipedes. Also, for crabs and other crustaceans. Was the leg count static?

I want my flying monkeys and birds with arms as well as wings and and feet! ?

In this regard, panarthopods (arthropods proper, onychophorans, tardigrades) are very different from vertebrates. They have two limbs on most of their segments, though in millipedes, most of their segments are fused to make segments with four limbs each.

Panarthropods vary a lot in how many segments they have, though many groups of panarthropods have fixed final numbers of segments.

Their limbs may be specialized as mouthparts or antennae, and they may also be lost. Regaining lost limbs is rare, but it has happened, like in caterpillars.

Vertebrates are also segmented, though it is less obvious. Backbones are segmented, along with associated parts like ribs and some muscles. Unlike vertebrate limbs, vertebrate backbones have a lot of variation in the numbers of vertebrae that they contain.

For bats, the majority of the wing is between their elongated fingers.

@WilliamCharles Yes. They can use them for grasping, climbing, feeding.

But generally, everything is a trade off. What does a creature lose by the ability to digest putrescence?

@WilliamCharles in the case of vultures, perhaps the specialized diet gave them a food source with very little competition in exchange for the ability to forage multiple food sources. It also seems like they sacrificed speed in flight and perhaps the lethal talons that raptors have.

@WilliamCharles it might be that there is a physiological 'cost' in producing such strong acids and hosting virulent bacteria, ie. Thicker stomach lining, less efficient digestion, more amped up immune responses etc.