The Tyrannosaurs Rise to Power

So how did the tyrannosaurs rise to power? This is my take on how it happened everything stated here is purely my opinion. The tyrannosaurs first appeared during the Jurassic. They were small, overshadowed by larger carnivores. The tyrannosaurs did not get any bigger than carnivores like Guanlong. Then, at the end of the Jurassic or the beginning of the Cretaceous, these early tyrannosaurs crossed a land bridge between Asia and Alaska. They had begun their invasion into N. America. When they got there, the role of top predator was already taken by Utahraptor and Acrocanthosaurus. The land bridge disappeared and the American tyrannosaurs were cut off from their Asian cousins. The American tyrannosaurs stayed small. Then, the Western Interior Seaway formed. This cut off tyrannosaurs in the east from those in the west. The Acrocanthosaurus' and Utahraptors in the east suddenly had less space and prey. They eventually died out. The tyrannosaurs in the east took over. Basal tyrannosaurs like Appalachiosaurus and Dryptosaurus became the apex predators. In the west however, there was still enough room and prey for the Acros and Utahs to continue their role as top predator. After a few million years, the earth began to cool. The seaway gradually began to shrink. The cooling climate caused the prey in the west to go extinct and Acro and Utah soon followed. New herbivores, better adapted to this new climate, showed up. And the tyrannosaurs, still small, took full advantage of that. They increased in size from 10 ft, to 30+ ft. Predators like Gorgosaurus and Daspletosaurus appeared. Finally, the seaway disappeared entirely. The basal tyrannosaurs in the east were still cut off by the Appalachian mountains. They would continue to be the top predators there. In the west, Albertosaurus was the apex predator. Albertosaurus was the last large carnivore that ever walked N. America before the arrival of a new species. Albertosaurus went extinct and the role of top predator was once again open. It would be filled by what may have been the greatest carnivore the world has ever seen. One who's name instills fear even today. Tyrannosaurus rex. With the appearance of T-rex, the tyrannosaurs rise to power was complete. That's how I think they became the top predators. Like I said, this is all based on my theories and opinions. Thanks for reading.