The Ark
Noah's ark was actually bigger than we currently think it was. The Bible says it is cubits big, 300 x 50 x 30 to be exact. The general thought behind cubits is that they are 18 inches long, because that is what modern cubits are. The problem with that, however, is that when Moses wrote Genesis, a cubit was the length from elbow to wrist (hand?), which could have been considerably longer. IN fact, a Royal Egyptian Cubit is 20.6 inches, not 18.
So, according to popular theory, the ark was:
450' x 75' x 45' = 1518750 square feet
But, using Egyptian measurements, they are:
515' x 85.833' x 51.5' = 2276505.7425
a total increase of 65' x 10.833' x 6.5' or 757755.7425 square feet more... It was 50% bigger than we currently think it was.
Now, let's look at how animals could fit in there...
the standard animal's size is a sheep. All animals, average, = sheep...
http://www.talkorigins.org/indexcc/CH/CH512_2.html
So, 250 sheep can fit in a railroad car...
Let's assume there are 20,000 different kinds of animals that need to go in pairs on the ark... That means that we need to have 160 railroad cars worth of space on the ark.
http://www.christiananswers.net/q-eden/edn-c013.html
with a 18 inch cubit, the ark is as big as 569 railroad cars... lets take that number (even though I showed before that the real ark is 50% bigger than the average railroad car), that means that the ark had 409 railroad cars worth of space left on it if the animals were in it like they are on railroads... They had MORE than enough room on the ark for all the animals... Animals could have 4 or 5 times more space ont he ark than they get currently on railroad cars...
Also, animals didn't eat meat until after the flood.
Gen 9:2-3: "And the fear of you and the dread of you shall be upon every beast of the earth, and upon every fowl of the air, upon all that moveth upon the earth, and upon all the fishes of the sea; into your hand are they delivered. Every moving thing that liveth shall be meat for you; even as the green herb have I given you all things."
Therefore the ark was totally plausible...