Tyrannosaurus rex, T.rex, from the Greek tyrannos “tyrant” and sauros “lizard“ the “terrible lizard” is one of most well represented of the large theropods. It lived throughout western North America. It was a bipedal carnivore with a massive skull balanced by a long, heavy tail. The forelimbs were short and especially powerful for their size and two clawed digits. The most complete specimen measures 40 feet (12.3 m) in length and 12 feet (3.6 m) tall at the hips. Its estimated weight was 11 short tons (10 metric tons). While other theropods rivaled or exceeded T. rex in size, it is still the among the largest known land predators with the largest bite force. Studies have shown that the bite force ranged from 20 to 26 short tons (18 to 24 metric tons). Such forces could easily crush bone in order to extract the bone marrow. T. rex acted as both a predator and a scavenger. Studies have shown that T. rex had keen vision. It had bidocular vision with a binocular range of 55 degrees, surpassing that of modern hawks with 13 times the visual acuity of a human which would have allowed T. rex to discern objects at distances of 4 miles (6 km) which is greater than the 1 mile (1.6 km) as human can see. Large olfactory bulbs provided an enhanced sense of small, comparable to that of modern vultures, implying that T.rex could detect carcasses by smell across great distances. T. rex had a very long cochlea, indicating that hearing was a particularly important sense amongst T. rex. Studies of the the ratio of cerebrum to brain mass indicated that T. rex had the largest brain of all adult avian dinosaurs.