Everyone knows Tyrannosaurus Rex, but some people do not know that Tyrannosaurus Rex had a cousin in Asia: Tarbosaurus. Tyrannosaurs Rex and Tarbosaurus were so similar in size and appearance that paleontologists initially thought they were the same animal. It was only thanks to subtle differences in their skull structures that they could tell these animals apart. Just as Tyrannosaurus Rex ruled North America, Tarbosaurus ruled Asia. It was the apex predator of Cretaceous Mongolia. Because of its relation to Tyrannosaurus Rex, some scientists theorized that a few Tarbosaurus migrated a land bridge that connected North America and Asia. Over time, those Tarbosaurus evolved into Tyrannosaurus Rex. Tarbosaurus will make an appearance in my dinosaur series as a genetic donor in the creation of my fictional dinosaurs.