Name: Tyrannosaurus (Tyrant lizard) Phonetic: Ty-ran-no-sore-us Named By: Henry Fairfield Osborn - 1905. Synonyms: Dinotyrannus megagracilis, Dynamosaurus imperiosus, Manospondylus gigas, Stygivenator molnari. Classification: Chordata, Reptilia, Dinosauria, Saurischia, Theropoda, Tyrannosauria, Tyrannosauridae. Species: T. rex (type) Type: Carnivore. Size: Most complete specimen 12.3 meters long, isolated remains suggest a potential upper size of around 13 meters long. Known locations: Western North America. Time period: Late Campanian/Early Maastrichtian of the Cretaceous. Fossil representation: Over 30 individuals are known, some forming almost complete skeletons.
Tyrannosaurus rex has been known to science since the end of the nineteenth century, and to this day remains arguably the most popular dinosaur the world over. This is evidenced by its almost mandatory inclusion in books, TV shows, games and websites that are about dinosaurs in general. Tyrannosaurus also probably has more toys and merchandising relating to it than any other dinosaur. There are a large number of fossils not just for Tyrannosaurus, but for the tyrannosaurid group as a whole, that represent individuals of different ages and their corresponding sizes. When these sizes and ages are put together, an S shaped growth curve is clearly displayed. This indicates that for roughly the first third of their lives, the tyrannosaurids grew quite slowly, reaching about a tenth of their full potential size. When they became teenagers however, they underwent a massive growth spurt, reaching nearly their full adult size in only about ten years. After this spurt, the rate of growth levels off as dramatically as it began when the individual reaches approximately twenty years of age.While this is a common trait for the tyrannosaurid group, the rate of growth for Tyrannosaurus is even greater than the smaller tyrannosaurids like Gorgosaurus. This is even more spectacular when you consider that Tyrannosaurus is not thought to have lived any longer than its smaller brethren, but still grew meters longer, and several tons heavier.