THE LEFT LEG OF A TYRANNOSAURID

Tarbosaurus, lived two to five million years before their famous North American relatives Tyrannosaurus rex. These large theropod dinosaurs lived in, what is now, modern Mongolia during the Maastrichtian age of the upper Cretaceous, shortly before the mass-extinction event at 65.5 Mya.

Discovered in 1946, the holotype of Tyrannosaurus baatar was described by Maleev in 1955; subsequent publications renamed the genus Tarbosaurus (1965) and Jenghizkhan (1995). Recent studies have suggested all the names may be synonymous, and others that the there are two distinct lineages of Tyrannosaurids evolving separately in Asia and North America.