The Largest Predator To Walk During The Cretaceous Wasn't A Dinosaur?

If you to travelled back to North America, anywhere from 83 to 77 million years ago, you would find the lands covered with dinosaurs, many of which were giant. However, they wouldn't be the largest things you could 'run' into, as during those times that largest creature in North America was not a dinosaur, it was a.....