An average Tyrannosaurus Rex had arms that were only about 1 meter (3 feet) long. However, with a 1 1/2 meter jaw filled with 50 to 60 nine-inch serrated teeth, the T-Rex may not have needed to use his hands much! Bite marks on other fossils suggest that he could bite through solid bone! And if he broke a few teeth here and there, no big deal -- new ones continually grew in to replace those that he lost. Standing up to 15 meters high and weighing more than 5 tons, Tyrannosaurus Rex was massive -- but he was not the largest carnivorous dinosaur. Giganotosaurus was even bigger.