C. T. Suddeth

T-Rex (Tyrannosaurus rex or tyrant-lizard king) lived in North America and no doubt made the mammals miserable. It was about 12 feet high at the hips and 40 feet long, weighing 18,000 pounds. It had excellent hearing, smell, and sight. Moving about 20 MPH, it was thought to have preyed on larger dinosaurs, mere people-sized meals only a snack.

Its nearest living relative is an ostrich, though chickens have also been compared. Alligators and such are close relatives of the 4-legged dinosaurs T-Rex preyed upon.

And yes, T-Rex was lightly feathered.