The Tyrannosaurus Rex “tyrant lizard king” was a powerful predator of the Cretaceous period. They are one of the largest of the known carnivorous dinosaurs - Tyrannosaurus rex - T. rex, for short - is the dinosaur that has arguably received the most media exposure. Because they spawning a huge number of books, movies, TV shows, and even video games. The name Tyrannosaurus rex means "king of the tyrant lizards": "tyranno" means tyrant in Greek; "saurus" means lizard in Greek, and "rex" means "king" in Latin. Its fossils have been found in places such as Texas, Nebraska and Montana. Their length was up to 12 metres (40 feet) from head to tail, stands 3.66 meters (12 feet) tall at hips and weighed about 7 to 9 tons. They could sprint up to 20 mph (32 kph). In 1997 the Field Museum of Natural History in Chicago purchased an 85% complete Tyrannosaurus rex fossil skeleton (nicknamed ‘Sue’ after its discoverer Sue Hendrickson) for 7.6 million US dollars, making it the most expensive dinosaur skeleton to date. T. rex was a huge carnivore and primarily ate herbivorous dinosaurs, including Edmontosaurus and Triceratops. Just imagine a hungry, eight-ton Tyrannosaurus Rex taking on a five-ton Triceratops, a not-inconceivable proposition since both of these dinosaurs lived in late Cretaceous North America. Granted, the average T. Rex would have preferred to tackle a sick, juvenile or newly hatched Triceratops, but if it was hungry enough, all bets were off. It suggests that puny forelimbs on a savage meat-eating dinosaur were not a joke. Tyrannosaurus Rex had powerful back legs that let it hunt prey over short distances at up to 20mph (32 kph). They would have charged out of the undergrowth to surprise their prey - and their flexible neck helped them adjust the angle of attack. The fact is, though, that T. Rex was outclassed by not one, but two, dinosaurs--the South American Giganotosaurus, which weighed about nine tons, and the northern African Spinosaurus, which tipped the scales at 10 tons. Sadly, these three theropods never had the chance to square off in combat, since they lived in different times and places, separated by thousands of miles and millions of years. There is also strong debate about whether Tyrannosaurus rex was a predator or scavenger. It had small arms which would have made it hard to grip prey, suggesting it may have been a scavenger. On the other hand, evidence in favor of it being a predator includes its forward pointing eyes which give better depth perception and make it easier to hunt. Paleontologists argued about whether T. Rex was a savage killer or an opportunistic scavenger--that is, did it actively hunt its food, or did it tuck into the carcasses of dinosaurs that had already been felled by old age or disease? This controversy seems rather quaint, as there's no reason Tyrannosaurus Rex couldn't have pursued both behaviors at the same time--as would any respectable carnivore that wanted to avoid starvation. What's truly amazing, though, is how much about this carnivore that was once assumed as fact has lately been called into question, and how much is still being discovered.