Named Lythronax argestes in a PLoS One study by Natural History Museum of Utah paleontologist Mark Loewen and colleagues, the 23 foot long tyrannosaur lived about 12 million years before Tyrannosaurus and trod a part of southern Utah that laid near the coast of a long-lost subcontinent called Laramidia. The pieces of skull and postcrania were discovered within the vast wilderness of Grand Staircase-Escalante National Monument. Yet, despite the distance in space and time, the skull of Lythronax holds a remarkable resemblance to Tyrannosaurus.

Rather than having a narrow, streamlined skull typical of later tyrannosaurid dinosaurs found further to the north – such as Gorgosaurus and Daspletosaurus – Lythronax shared with Tyrannosaurus a skull that widened towards the back, giving these