To say "I'm not sure what this is?" would not be an understatement. This started out as a new "dog" or "wolf" mech and sort of went in a different direction. Just how I would describe the finished design I'm not sure.
What I am certain is that it isn't a "creature", it is intended to represent a machine. But what kind of machine I leave up to you.
I've placed this in the Medieval Universe, which is basically a hybrid of Castle themed mecha and other "fantasy" designs. I'm not sure what a flightless dragon might be called, but for now, this is one.