But the winner wouldn't have been the dinosaurs.
The dinosaur was here before large mammals and humans.
So here's the deal.
The dinosaur would not be able to survive today.
Its more of a case of, The dinosaurs ruled because it had no competition in the Mesozoic...
Mammals were extremely small, and couldn't take on the dinosaur.
Bring in a dinosaur today, and mammals would completely outsmart it, and outrun it.
So animals of that type can no longer evolve, because much better is here that can, and would outclass it in nearly every way.
And visa versa...
Bring us back to the Mesozoic, and we would have simply been the end of the Dinosaur.
Us and Dinosaurs are two entirely different concepts of what life is, and we have a great advantage.