How did dinosaurs get so cool? One of the reasons may have been that unlike us, they could evolve in a world where there was no USA. In the cretaceous period, much of North America was covered by water. This is what America looked like when it was home to dinosaurs like T. rex, Triceratops, Ankylosaurus or Deinonychus.
I once read an article detailing how the interior sea was the reason for all the fertile soil in the American Southeast
That's interesting. Sounds as if that's the area where most of the sediment swept into that seaway ended up.
I believe it also had a lot to do with millions of years of shells being laid down on the sea floor.