Modern day dragons are, in Western culture at least, imagined as huge, reptilian, fire breathing creatures with both legs and wings. However, as far as I can find out myself by research, dragons were developed from ancient mythical creatures that were more akin to gigantic serpents or worms. In ancient Germanic lore at least, they were called "worm", "orm", "wyrm" and later "lindworm". Now worms or snakes don't normally have legs or even wings. But up through the ages, these were added to their characteristics.
The epic poem of Beowulf was the first to describe a dragon/wyrm as having a fiery breath and bat-wings. Lindworms are often pictured in Romanesque art adorned with wings. Does anyone have a clue, at what stage, and under influence from what cultural tradition, did wings (and fiery breath) get added to the dragon as to arrive to our modern concept of these legendary beasts?