Palaeontologists have discovered a new species of tyrannosaur in Alberta. Thanatotheristes degrootorum is the oldest tyrannosaur species ever found in Canada, according to an article published by researchers from the University of Calgary and the Royal Tyrrell Museum of Palaeontology in the journal Cretaceous Research.

“We are thrilled to announce the first new species of tyrannosaur to be discovered in Canada in 50 years,” said Dr. François Therrien, Curator of Dinosaur Palaeoecology at the Royal Tyrrell Museum. The last tyrannosaur described from Canada was Daspletosaurus in 1970.

Tyrannosaurs were a group of large predatory theropod dinosaurs (bipedal meat-eaters) that includes the famous Tyrannosaurus rex.

Scientists were able to conclude that this is a new, distinct species by analyzing the unique features of fossil skull fragments. “Thanatotheristes can be distinguished from all other tyrannosaurs by numerous characteristics of the skull, but the most prominent are vertical ridges that run the length of the upper jaw,” said Jared Voris, a University of Calgary Ph.D. student, and lead author of the study.

At roughly 79.5 million years old, Thanatotheristes is 2.5 million years older than its closest relative. There are only four other tyrannosaurs known from Canada: Daspletosaurus, Gorgosaurus, Albertosaurus, and Tyrannosaurus.

Most dinosaur species from Alberta date from between 77 – 66 million years old. There are only two other dinosaurs known from Alberta from the same time period as Thanatotheristes: a dome-headed dinosaur (Colepiocephale) and a horned dinosaur (Xenoceratops).

The name of the new tyrannosaur alludes to its role as an apex predator, and was inspired by Thanatos (Greek god of death) and theristes (one who reaps or harvests). The second part of the name honours the De Groot family.

John De Groot, a farmer and palaeontology enthusiast, found the fossil skull fragments while hiking near Hays, Alberta. “The jawbone was an absolutely stunning find. We knew it was special because you could clearly see the fossilized teeth,” he said.

John and Sandra De Groot have been valuable supporters of palaeontological fieldwork in southern Alberta. According to Sandra De Groot, “John always said that one day he would find a dinosaur skull. Finding the jaw was exciting. Hearing that it is a new species, and seeing it given our family name, was beyond belief.”

“This discovery is significant because it fills in a gap in our understanding of tyrannosaur evolution,” said Dr. Therrien. Thanatotheristes provides scientists with insights into the tyrannosaur family tree, and shows that tyrannosaurs from the Cretaceous of Alberta were more diverse than previously known.