I wouldn’t be surprised if you’ve gotten this question before, so sorry if this is a repeat, but would it be at all realistic to have a wyvern with a sort of hybrid of bat and bird wings? Like could you have something where the back of the wing was covered in feathers but the front was bare? Or is that just unnecessary cumbersome? I assume it would be feathers for insulation rather than flight feathers

drferox:

Feathered wings are an aerodynamic adaption. They have developed to guide air smoothly over the wings, from front to back. If you want a ‘realistic’ hybrid wing, you would find feathers on the front edge, just small ones to round out and smooth the shape for gliding, and continue into a membrane towards the back.

For this hypothetical wyvern, there has already been a real word possible analogue, the Yi qi. This specimen has a kind of hybrid wing, which unfortunately didn’t do well in evolution. Otherwise we might have dragons.

You could presumably have an animal that had feathers all over its body and tiny ones along the edges of the wings, like pterosaur fuzz. Feathered wings start out as feathered limbs with large feathers that can provide a tiny bit of extra hangtime on a jump, so it’d be a bit odd for a feathered animal to start growing skin-flap wings instead of large feathers, but I suppose it could happen.