No Dianasours on the Ark: Why?

Given the 24/7 coverage of  the floods going on everywhere I have been flooded with thoughts of  flooding and then been totally enthralled by how much "Noah" and "the Ark" humor there is about.

However, the most interesting or should I say amusing question is:
Why were there no Dianasours on the Ark?

Especially when you allow acceptance of some views that say all the species existed together or at the same time.

Some of the possible (humorous) answers to the question follow by way cartoons that I found on the net -

The they were to lay back from all the hemp and reeds they ate - theory?
They just missed the boat.

There were two Arks and only the one with the big brain stems made it - theory?
Also known as the aggressive bastards shall inherit the earth - theory?

The blame the man theory - preferred by females?

The scientific theory - preferred by geeks?

Enjoy and ponder and wonder if its not better for some things just to remain as question.