‘Reaper of Death’ is Canada’s newest tyrannosaur

Thanatotheristes degrootorum is one of the oldest tyrannosaurids ever found
thanatotheristes An artist's impression of new tyrannosaur species, Thanatotheristes. (Julius Csotonyi)

Tyrannosaurs tend to get thought of as one dinosaur — the almighty Tyrannosaurus rex. But even though the ancient predator is the most famous dino of all time, there were all sorts of tyrannosaur species out there.

After all, these animals lived across tens of millions of years! As time passed, these reptiles evolved and grew from raptor-sized hunters into massive beasts like T. rex and Tarbosaurus. New evidence of this is being found all the time, including here in Canada.

Introducing Thanatotheristes degrootorum (say thah-NAH-tuh-ther-IHZ-teez duh-GROO-toh-ruhm), a.k.a. the 'Reaper of Death', a.k.a. Canada's first new tyrannosaurid fossil in 50 years!

"That's quite the name you've got there..."

thanatotheristes reaper of death

The pieces of jawbone with the outline of what the dinosaur's head probably looked like. (Jared Voris)

So, reaper of death, huh? How did that name come to be?

For that answer, we go to Jared Voris. This Ph.D. candidate at the University of Calgary has spent the last two years working intensely on the Thanatotheristes fossil. Its fossil — several fragments of jawbone and teeth — was first found in 2010 by Alberta ranchers, Sandra and John De Groot (which is where 'degrootorum' comes from). The fossil was safely filed away at the Royal Tyrrell Museum until someone was able to study it properly.

That someone was Voris. And as he studied it, he started to realize that it might actually be an entirely new species of tyrannosaur. And a pretty gnarly one at that! A friend suggested that Thanatos, the Greek god of death, might be a good fit. And the rest is history!

Lean, mean hunting machine


Smaller than T. rex. Bigger than you. (Julius Csotonyi)

The name 'reaper of death' suggests a swift and deadly creature. And Thanatotheristes likely lived up to the description.

Though not nearly as large as a T. rex, it was about the length of two cars from head to tail. It was about 2.4 metres (8 feet) tall. It lived about 79 million years ago, which is about ten million years earlier than Rex. In fact, it is one of the earliest tyrannosaurs every discovered. It would have likely been a top, or apex, predator in its time.

The only way to be more sure of this? Find more fossils of Thanatotheristes! Though that might be easier said than done, recent discoveries have proven that there are plenty more fossils out there to be found.

In an interview with CBC, Voris said that "one of my goals now is to see if we can find more of another individual and see how to see exactly how different it is from some of the other tyrannosaurs in Alberta. I have a hunch that it might be pretty different."

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  1. I always thought that TRexs were the only Tyrannosaurs. Guess not!! And Reaper of Death is a really neat but terrifying name!! 🦖

  2. This dinosaur is different. The dinosaur is red. The teeth can crack and eat bones. They are biting herbivores which eat plants. This dinosaur is a carnivore which eats meat. The dinosaur roars. I wonder if the skin over the eye shaded the eye. Dinosaurs are scary. We are afraid of dinosaurs. They lived a long time ago, so we don’t need to be afraid.

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