Why has no one ever made a variant owlbear that can fly?
Sage: And here we have an excellent taxidermal model of strigiformes ursus, commonly known as the owlbear.
Fighter: Your stuffed toy here sure has some long arms and big feathers. What are these, roc feathers? Your taxidermist ought to be fired for this obviously fake mock-up.
Sage: Oh no, this specimen was brought in from the Crystalmist mountains, and it was quite advanced in age. Those feathers allowed it to fly.
Fighter: Say wha...?
Sage: Yes, apparently, if allowed to live long enough, they reach a point of maturity at which they can fly. Takes some time - over forty years if my research is correct....Now - on to the hall of behemoths....
Also, I would veer away from the quadraped owlbear. It looks too similar to a wingless griffon.