Quadropedavia! Keeled sternum (youd need a big one to attach the kind of flight muscles that would get this guy off the ground), modified scapula. My pegasus are fully feathered, including a ruff around their necks into which they can tuck their front feet to make them more aerodynamic. They have a feathered tail that acts as a rudder, although it does have a bone in it. Their feathered manes also help them maneuver in the air and are used socially for signaling mood. They have hollow bones and a birds complicated lung system to get enough oxygen for those flight muscles. They have a cloaca. They lay eggs. They are technically monotremes.
Things I dont like: I think the skull should have been smaller, and it should look lighter than a horse skull (which it doesnt). I think I should have made the spine longerlike a crane as opposed to a song bird. He looks too bunched up.
This is amazing! Maybe the proportions aren't as perfect as you wanted, but it's an incredible interpretation. Fairly accurate, believable, and just darn magnificent, as a pegasus should be.
Very nice! I keep noticing how typical "wings" on a Pegasus are impossible for flight in all the other drawings and it is refreshing to see a diagram that smoothly blends both horse and avian properties. And as for the skull, I think that if it like the other bones, would be lightweight as well? Some of the other bird skeletons I have seen had quite large heads in comparison to their bodies and I would guess that the head could help in balance during flight?