One of the key peices of evidence that people sight to try to prove the flood happen is the fact the most cultures have a flood myth or story as they put it.
I was just watching a program that also points out the most, if not all cultures believe in dragons. Even cultures that evolve in isolation have beliefs in dragons and they are all simular though not the same. Just like the flood myth.
So if they believe the flood happened because so many cultures have flood stories. Then by the same stroke they most also believe that dragons walk the earth.