This makes me want to finally get around to Calvert Watkins's How to Kill a Dragon, which argues that you can do a similar historical reconstruction on poetic forms and motifs as linguists have done with languages, and arrives at hypothetical proto-Indo-European dragon-killing story (I don't remember if he gets to an actual reconstructed poem or not). It seems the PIEs killed dragons by putting something nasty in their mouths or by hiding under them and stabbing their belly.