Hmm...
Presumably if the original Ark had been larger Noah could have saved the dinosaurs as well. Sounds like a bit of not-very-intelligent design somewhere. Perhaps there had to be a compromise...
Noah: "How's it going then?"
Builder: "Well, [sharp intake of breath] we're still waiting for half the animals to be delivered and who knows where the rest of the sodding gopher wood has got to. Might have to cut it down to three decks and delete the billiard room if we're going to make the deadline. I don't know who did the design for you, but they should never have specified pitch on the inside - most of the small rodents are stuck to it. This sodding rain isn't helping either..."