This is the third question in a series of such for my worldbuilding project that deals with plausible fantasy creatures. Previously, I have pondered cockatrices and hydras, but now we move on to another popular mythical animal, the griffin. Last two questions: Is petrifying vision plausible in an animal? and Hydras as parasitic-mating, polyandrous amphibians?
The griffin, or gryphon, is a well-known beast of fantasy that was depicted by the Egyptians, Iranians, Minoans, Greeks, Romans and Medieval people. It is said to have the body and forelegs of a lion and the head, wings and hind legs of an eagle. However, the consistent thing in all portrayals of griffins is that they have four legs and two wings.
Yes, flying quadrupeds, Bane of Worldbuilders. Such an anatomy would require the griffins to be hexapods, which isn't realistic evolutionarily. So, hexapodal griffins must be ruled out. When I realized this shortly after considering including griffins in my worldbuilding project, I thought that I'd have to simply leave them out.
But then I remembered a real-life group of giant flying animals, the Azhdarchids. The largest species in this group being the giraffe-sized Quetzalcoatlus northropi, they walked with their wings as their forelimbs.
Could a bird evolve such locomotion? My premise is that these griffins could have evolved from Accipitrids or similar birds, and grown larger and larger until they gained a wing-walking posture to sustain their massive size. Hypothetically, their movement would be very Azhdarchid-esque, and it would be about the size of a horse.
Now to the real question: would massive wing-walking birds a) evolve rather than some other method of sustaining their frame, and b) survive and hunt with such adaptations?