Anyone can make up a story. It's when it comes to committing to writing them down that I have problems.

There are places in the desert where fossilised bones of dinosaurs, and their nests and eggs, can be found on the surface. The variety of dinosaur had a head with an eagle-like beak and it would be easy for people to see the skeletons and say "Oh wow, look, a HUGE four legged eagle!!" and since eagles have wings, bingo, that's a gryphon! Griffin, however you want to spell it. The Scythians seem to have loved them and put them on all kinds of things.