Scientists have discovered a new species of dinosaur closely related to Tyrannosaurus rex that strode the plain of North America some 80 million years ago.
Thanatotheristes degrootorum – Greek for "Reaper of Death" – is thought to be the oldest member of the T-Rex family yet discovered in northern North America.
The "lightweight and exceptionally fast" Moros intrepidus lived about 96 million years ago and would have grown to around 8 meters in length.
Paleontologists believe that the diminutive dinosaur, with hind limbs measuring 1.2 meters and weighing around 78 kilograms, is the link connecting medium sized primitive tyrannosaurus dating from the Jurassic period (about 150 million years ago) to the dominant T-Rex of the Cretaceous period (about 81 million years ago).
"We chose a name that embodies what this tyrannosaur was as the only known large apex predator of its time in Canada, the reaper of death," Darla Zelenitsky, assistant professor of Dinosaur Palaeobiology at the Canada's University of Calgary.
"The nickname has come to be Thanatos," she told AFP.
Whereas T-Rex – the most famous of all dinosaur species, immortalized in Steven Spielberg's 1993 epic Jurassic Park – stalked its prey around 66 million years ago, Thanatos dates back at least 79 million years, the team said.
The specimen was discovered by Jared Voris, a Ph.D. student at Calgary, and is the first new tyrannosaur species found for 50 years in Canada.
"There are very few species of tyrannosaurids, relatively speaking," said Zelenitsky, co-author of the study that appeared in the journal Cretaceous Research.
"Because of the nature of the food chain, these large apex predators were rare compared to herbivorous or plant-eating dinosaurs."
The study found that Thanatos had a long, deep snout, similar to more primitive tyrannosaurs that lived in the southern U.S.
The researchers suggested that the difference in tyrannosaur skull shapes between regions could have been down to differences in diet, and dependent on the prey available at the time.