How surprising!
Obviously the intact specimnens had to have died in the flood waters, or else their bodies would have been ravaged by predators.
This had nothing to do with extinction; they were still alive in the middle ages in sufficient numbers to have a huge representation in the written historical record.
If dinosaurs lived during the Middle Ages why is it that we have discovered no dinosaur remains above the K-T boundary?
Would you then care to enlighten us with the evidence in the historical records of dinosaurs being both alive and numerous during the middle ages? And while you are at it please tell us how you differentiate between historical accounts and fictional entertainment.