Bobcat,
Very interesting thoughts regarding the Sign of Jonah.
Since the Pharisees believed that a man wasn't dead until three days had elapsed; and that we know it would be very difficult for a man to remain alive in the belly of a fish (or whale), could it be that Jonah was actually dead for those three days and was made alive again when he was expelled onto the beach?
Jesus also let his good friend Lazarus go for three days (perhaps to show the Pharisees that he was really dead) before going to him to bring him back to life. Nobody could deny that Lazarus had died and yet he was miraculously brought back to life. The strongest form of proof that even the Pharisees could not reject.