Tyrannosaurids, the family of dinosaurs that includes T. rex, has been known from North America and Asia for over a century, yet many details of their evolutionary history remain unclear. Since the 1990s, debate has surrounded Daspletosaurus, a large tyrannosaurid known from Montana and Alberta, which has been proposed to be an ancestor of T. rex itself.
Click here for original story, New species of tyrannosaur, Daspletosaurus wilsoni, hints at ancestor of T. rex
Source: Phys.org