They probably didn't make it onto Noah's legendary craft because they were too big and crapped too much.
It's either that or with the discovery that so many dinosaurs sported feathers, Noah thought they were birds and could just fly around until it stopped raining.
But apparently with nowhere to land except Noah's yacht, owing to their size Noah had them repeatedly sticked off. So now they're all dead except for small birds and birds like penguins that were good swimmers.
But lots of dinosaurs were totally aquatic. Such a mystery, right up there with how reindeer can stay airborne.