 Tyrannosauridae ( or tyrannosaurids , meaning " tyrant lizards " ) is a family of coelurosaurian theropod dinosaurs which comprises two subfamilies containing up to eleven genera , including the eponymous Tyrannosaurus . The exact number of genera is controversial , with some experts recognizing as few as three . All of these animals lived near the end of the Cretaceous Period and their fossils have been found only in North America and Asia . 
