Voris found one set of fossils that stood out from the four species of tyrannosaurs known in Alberta.
The predator's name - Thanatotheristes degrootorum - translates to "Reaper of Death" from the Greek. "Hearing that it is a new species, and seeing it given our family name, was beyond belief", added Sandra De Groot.
The De Groots found the fossils, including jaw bones and skull fragments, in 2008 as they hiked along a riverbank in Alberta.
"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."
Tyrannosaurs, or "tyrant lizards", were the dominant predators on land for millions of years before the extinction of dinosaurs some 65 million years ago.
"The jawbone was an absolutely stunning find", said John.
"We'd find one feature, and then we'd find another, and then it would just kind of cascade into finally understanding that this was something completely different than what we'd seen before", said Voris, who is now working on his PhD in paleontology at the University of Calgary. "We knew it was special because you could clearly see the fossilized teeth", De Groot said in the statement. All three species form a newly named group of dinosaurs called Daspletosaurini.
Francois Therrien, curator of dinosaur paleoecology at the Royal Tyrrell Museum of Palaeontology, says the specimen was collected in 2010 and has sat in storage ever since.
Another species of tyrannosaur, a Daspletosaurus, was found in Canada in 1970, a study says.
Researchers have discovered a large new species of tyrannosaur that lived around 80 million years ago and was closely related to the iconic Tyrannosaurus rex. This now-oldest member of the T-Rex family tree goes by the cuddly name 'Reaper of Death'.
Dubbed Thanatotheristes degrootorum, the ancient creature is the oldest tyrannosaur known from Canada and northern North America.
According to the team, T. degrootorum is one of the oldest tyrannosaur species ever discovered in North America and is at least 2.5 million years older than its closest relative.
"These [features] differ from tyrannosaur groups in other regions: the more lightly built relatives, like Albertosaurus, that tended to live slightly farther north in south-central Alberta, and more primitive forms with shorter, bulldog-like faces of the southern US, [including] New Mexico and Utah", added co-researcher Darla Zelenitsky to Live Science. "Here in Alberta we already have five".
"From some areas of the province you can collect up to six, maybe more, skeletons of dinosaurs every summer", he told the ABC.