The ethnologists Alexander Haggerty Krappe (“La genese des Mythes“), believe that the dragon myth originated from primitive peoples finding large skeletons of dinosaurs and postulating how they appeared during life.
Others theorists believe that forms of dragons still exist on earth today. The Loch Ness Monster is the primary modern example of a potential “water dragon”.
Some anthropologists admit that fire-spitting creatures are possible.
Animals with chambers for gases such as methane and a way to rub stones together in a large gizzard could conceivably breathe fire. Bombardier beetles, for example, spit vaporized acid out of their abdomens.