Voris' PhD thesis supervisor, Darla Zelenitsky, believes Thanatotheristes is a direct ancestor of the infamous lizard king and predates T-rex by 12 million years, making it the oldest known Tyrannosaur ever discovered in Canada.
Alberta, Canada is known within the paleontology community for its plethora of tyrannosaur remains - Albertosaurus, Gorgosaurus, Daspletosaurus, Tyrannosaurus rex and now Thanatotheristes degrootorum.
The newfound species, Thanatotheristes degrootorum, lived around 80 million years ago, and the first part of its name means "reaper of death". If you are still unfamiliar with the "tyrannosaur" term, maybe T-Rex will ring the bell as it is one of the most known of the tyrannosaur species. It was found by John and Sandra De Groot, for whom the species was named, on the shore of the Bow River near Hays, Alberta, in 2010. The Reaper, with more physical heft than its predecessors, roamed this area as a risky predator in its own right roughly 79.5 million years ago.
Jared Voris was examining skull fragments stored in a drawer at the Royal Tyrrell Museum in Drumheller, Alta., as part of his masters thesis when he noticed features not seen in other tyrannosaur specimens.
"Probably the most obvious difference for the general public is the presence of a series of vertical ridges on the upper jaw, and those probably in life would have been covered by scales."
Thanatotheristes is thought to be the oldest member of the Tyrannosaurid family found in Canada and much older than others found in North America. "We knew it was special because you could clearly see the fossilized teeth", he said.
Like its tyrannosaur relatives, the carnivorous dinosaur had a long, deep snout, bumps on its skull and large steak-knife-like teeth measuring more than 7cm (2.7in) long.
Thanatotheristes degrootorum was stalking what is now North America as a formidable predator 79.5 million years ago.
"Because of the nature of the food chain these large apex predators were rare compared to herbivorous or plant-eating dinosaurs". Interestingly, the fossil was found about a decade ago but it was not until recently that the study began.
The discovery, scientists said, allowed them to have new insights on the tyrannosaur's evolution.
"The jawbone was an absolutely stunning find".