Tarbosaurus bataar

Tarbosaurus bataar. Artist: Kate Nolan. Source: Museum Victoria.

Tarbosaurus was a carnivorous dinosaur from the Gobi Desert of southern Mongolia. Like its close North American relative, Tyrannosaurus, it was one of the last surviving dinosaurs. Although the skull of Tarbosaurus was large, it was not very heavy. This was because it was comparatively thin, and contained large air pockets. The vertebrae and ribs were hollow, as were the bones of the upper arms. Most saurischian dinosaurs had light, hollow bones, which allowed them to grow to large sizes, like Mamenchisaurus, or to be fast and agile, like Tarbosaurus.

The reason why the arms of the large meat-eating dinosaurs like Tarbosaurus are so small is a mystery. Some palaeontologists believe that the reduced weight of the arms helped these animals to keep their balance on two legs in spite of their having such very large heads. The head (and jaws) were used for attacking prey, but did not contain a large brain—in fact, it has been calculated that Tarbosaurus had a brain only one tenth of the size of what would be expected in a mammal!

The exhibit at Melbourne Museum is a cast of a fossil skeleton from the Nemegt Formation in the Gobi Desert.