|Meaning||Tyrant Lizard King|
|Height||15 to 21 feet|
|Weight||5 to 7 tons|
|Home||Rexville, Western North America|
Tyrannosaurus rex was a large meat-eater from the Cretaceous. It ate large dinosaurs, like Triceratops. Some scientists think that Tyrannosaurus could eat more than 200 pounds of meat in one bite. Tyrannosaurus lived during the Cretaceous in Western North America. The most notable Tyrannosauruses are the Tyrannosaurus family, Annie, Boris, Dolores and Buddy.
- Despite their loose resemblance to animals such as Allosaurus and Carnotaurus, Tyrannosaurus was not closely related to either of them. It and other tyrannosauroids are actually members of the theropod clade Coelurosauria, which mainly consisted of lightly built feathered animals such as dromaeosaurids, troodontids, ornithomimids, and even modern birds. Tyrannosaurus likely lacked feathers, but its less derived relatives, the proceratosaurus, retained them.
- Tyrannosaurus went through a distinctive ontogenetic niche shift as they grew from hatchling to adult. Juveniles bear very little resemblance to adults, and were fast-moving pursuit predators with lean builds and long, narrow skulls with bladelike teeth. By the time they become subadults, they begin to develop the more iconic traits seen in mature rexes, becoming slow-moving ambush predators and developing shorter, broader skulls with bone-crushing, spike-like teeth.
- Juvenile Tyrannosaurus look so radically from adults that some researchers classify them as adults of an entirely new genus called "Nanotyrannus". However, most evidence points to them simply being juveniles of Tyrannosaurus, rendering Nanotyrannus a dubious genus.