Some scientists have hypothesized that the more rigid skull of Tarbosaurus was an adaptation to hunting the massive titanosaurid sauropods found in the Nemegt Formation , which did not exist in most of North America during the Late Cretaceous .
Some scientists have hypothesized that the more rigid skull of Tarbosaurus was an adaptation to hunting the massive sauropods found in the location , which did not exist in most of North America during the later Cretaceous .