Noah's ark

I came across this:
http://hanxter.wordpress.com/2008/10/08/working-replica-of-noahs-ark-opened-in-schagen-netherlands/
Some guy built a working replica of the ark according to the bibles description. Well, I would just like to pose a little problem:
The Australian megafauna died out in Australia about 20,000 years ago. The aborigines arrived about 60,000 years ago, so they actually co-existed here for a while. Simple logic; if the aborigines arrived here by boats from Indonesia and the megafauna were already here then something is wrong with the Ark story.
If the Ark story was true then after the flood the megafauna would have had to migrate back from the middle east to Australia, the problem is that the last time the continents were connected was roughly 200 million years ago.

So one of the following must be true,

• They would have had to swim
• They came with the aborigines
• Noah existed 200 million years ago so the megafauna could walk home.
• God just placed them here after the flood
• Carbon dating and geological uranium dating are completely wrong.

Let's rule out the swimming as some animals can migrate across open sea by being stuck on a log, but these weren't your average marsupials they were huge.
Maybe the aborigines brought the megafauna with them by boat. However, one of them Megalinia prisca, was a 5.5m long carnivorous goanna weighing 600kg (1322 lbs). I'd like to see that in a fishing canoe lost at sea.
If Noah existed 200 million years ago then there are a lot of other questions that need answering, but none of the questions could really be taken seriously, so let's not go there.
God just placed them here. OK, but how did they get to the Ark in the first place? "And of every living thing of all flesh, two of every sort shalt THOU BRING into the ark" So Noah had to collect them! Well to give him credit at least he was 600 years old when it started to rain. How could 1 man and 3 sons collect every type of animal from Australia and take them back to the middle east? Not only that but he had to collect the food for them as well (Gen. 6:21). Now a Koala's diet is leaves from eucalyptus trees. So to take a Koala and it's diet all the way to the middle east and then have it survive for 40 days and then travel back again is impossible, the leaves would have dried out and the Koalas would have died. At no point in the story of the ark does it imply that the animals could survive without eating, so Noah would have had to take eucalyptus trees with him.
Carbon dating is wrong, ok, it is not perfect beyond 30000 years due to environmental contamination, but the bones of the megafauna have been found at aboriginal cooking sites so they definitely co-existed.

Perhaps a flood, say 6000 years ago, wiped out both the aborigines and the megafauna and then the continent was repopulated. The problem is that there is no geological record of a flood of that scale in Australia. Floods leave layers of sediment. Prestine bones of megafauna have been found in the caves of the Nullarbor, where the animals would go in and get lost or fall into earth holes. The bones would have had at least a sediment covering if there had been a flood. There is evidence that the megafauna may have actually been killed off by drought. That is why there is now the limestone caves of the Nullabor, the climate of the Nullabor was once a lot wetter than it is now and when it changed some of the megafauna were unable to adapt in geological time (the modern kangaroo has it's heritage in the megafauna).

I choose to see the Ark story as an allegory and someone who builds one as having too much money and too much time on their hands. And I would like to add that I think it is a crime that they would encourage other people to follow in the same pointless pursuits.