Pterodactyls would be air mobs that can be tamed with a bone like wolves. Also like wolves,they would follow their owner unless the owner encloses it in a building of some sort. Agin like wolves, they would have collars when tamed. When killed they would drop a bone. When a tamed one is following the player, one left-click makes the pterodactyl land. Two left-clicks make it stop moving. To fly it, the player would need to walk up to its back. It would be controled the same way as usual,but right-click on the ground to land. The player would also be able to use a bow while flying the pterodactyl.
Besides, a modder could easily replicate this, and it doesn't add anything new to the game other than 'omg flying wee'