Two T-Rex on the ark, huh? Well that would probably explain why a lot of species became extinct.
If Noah took T-Rex on the ark, they were probably babies.
However the way I read the flood account, I don't know that Noah necessarily took a pair of every land dwelling animal that was on earth prior to the flood. God caused the animals to come to Noah. And it's possible that God decided to leave some animals out. Since Genesis was written by Moses well after the flood, the reference to "every" animal, may mean every animal that we now have, as opposed to those that were in existence then.
I still have yet to get a rational answer (one not answered by claiming a miracle) from any creationist about how all the animals such as the sloth and the koala got to the ark, and how they got home when there was no food for them after the flood.
Forget the logistics of a boat so big it could carry all the animals and still be seaworthy, or the sheer notion that any of the fable could be true.
And when all the animals were let go, none of the tigers decided on zebra steak? LOL