Reaper of Death Tyrannosaurus Rex discovered in Canada ? Paleontology

Tyrannosaurus Rex discovered in Canada

Tyrannosaurus Rex? JARED VORIS is no stranger to death. By early 2018, the University of Calgary masters student had spent more than a year poring over bones in museum collections, studying how tyrannosaurs matured from hatchlings into hulking terrors. During one visit to the collections of Albertas Royal Tyrrell Museum of Palaeontology, noticed a cabinet with fossils he couldnt quite place.

Now, after two years of careful research, Voris and his colleagues have identified the first new Canadian tyrannosaurid to be found in 50 years. Stretching 26 feet in length, the dinosaur is named Thanatotheristes , Greek for reaper of death.

Aged roughly 79.5 million years, Thanatotheristes degrootorum sits near the base of the tyrannosaurs ascent to ecological domination. The unearthed skull fragmentsincluding upper and lower jawbones, teeth, and a partial cheekbonesketch out the early pages of how tyrannosaurids, the tyrannosaur subgroup that includes T. rex, rose to power and became top predators.

Tyrannosaurus Rex dinosaur

I tried to be really meticulous with identifying features that made it unique, says Voris, who is now a Ph.D. student at the University of Calgary. Its interesting to have the opportunity to name a new speciesand Im hoping it isnt all downhill from here.

When tyrannosaurs first arose some 165 million years ago, they werent the tyrants that eventually reigned over the Cretaceous period in Asia and North America. Some were downright tinyno bigger than five feet talland hunted in the shadows of the ages more massive carnivores, including the bus-size allosauroids andthe large-clawed megalosauroids.

About 80 million years ago, these other predators faded away, giving tyrannosaurs a chance to rise to the top of the food chain and grow into giants. By 66 million years ago right before its extinction, the infamous T. rex grew up to 40 feet long and weighed more than nine tons. But Thanatotheristes ,unveiled in Cretaceous Research on January 23, doesnt seem to have been as large or as hulking as T. rex , underscoring the diversity at the top of this periods food chain. ( Learn more about the worlds biggest T. rex yet found .)

It seems like tyrannosaurs had a dynamic evolutionary history, University of Edinburgh paleontologist Steve Brusatte , who wasnt involved with the study, says in an email. They werent all monstrous superpredators like T. rex , but there were many little subgroups that had their own domains and their own distinctive body types.

Hunting the reaper of Tyrannosaurus Rex

Tyrannosaurs were probably rare in life and even rarer as fossils. Regardless, filling in the groups evolutionary picture from bony remains is a challenging task. Their plant-eating peers evolved a striking variety of large neck frills and head crests that helped the animals spot their species, rivals, and potential mates. But tyrannosaurs lacked these billboards.

Its hard to tell when new species arrive in the fossil record, says College of Charleston paleontologistScott Persons, who was not part of the study team. You get into this real nitty-gritty. You have to really fine-tune your taxonomic observations.

Every scrap of tyrannosaur bone holds vital clueseven those found by chance, such as the Thanatotheristes remains. John and Sandra De Groot stumbled on the bones in 2010, as their family walked along the shoreline of southern Albertas Bow River. The pair contacted the Royal Tyrrell Museum, which sent paleontologists to collect the fossils and search for more. To honor the family, Voris team gave Thanatotheristes the species name degrootorum .

Theyve been an invaluable resource, Voris says of the De Groots. It just shows, you dont have to be a paleontologist to help out in paleontology.

Nearly a decade after the fossils were cleaned, catalogued, and stored, Voris and his colleagues began putting the paleo-puzzle together. The team focused on the jawbones, which had uniquely prominent ridges that hinted at long-lost facial structures. The animals cheekbone also had an oval shape in cross-section, unlike other closely related tyrannosaurids.

Tyrannosaurus Rex territory

The fossil provides a deeper look into the diversity of North Americas tyrannosaurs, many of which lived and died along the western shorelines of a mighty inland ocean that stretched from the Arctic Ocean to the Gulf of Mexico.

Thanatotheristes hails from an understudied rock formation, and at 79.5 million years old, the fossils provide clues into how early tyrannosaurids evolved into giants. Its the oldest known tyrannosaurid from northerly North America, says study co-author Darla Zelenitsky , a paleontologist at the University of Calgary and Voris doctoral adviser.

With the addition of Thanatotheristes , tyrannosaurs from the western U.S. and Canada appear to form two distinct lineages: a northern group with long, deep snouts, and a southern group with shorter, bulldog-like snouts. Perhaps this division reflects two distinct feeding strategies, each shaped by the regions varying prey and environment.

Tyrannosaurus Rex fossil

While it is unclear whats driving this pattern in North America, one possibility is the size of their prey. The large-bodied Asian tyrannosaur groupthat eventually yielded T. rex lived alongside huge plant-eating dinosaurs, including the long-necked sauropods. It is possible that these tyrannosaurs reached momentous sizes to more effectively take down such titanic prey.

There is much left to learn about this tantalizing pattern. Many gaps also linger in the tyrannosaur fossil recordespecially for Thanatotheristes . Aside from one small jaw fragment found at another Albertan site in 2018, the Bow River bones are the only known fossils of this predator. Return expeditions to the site where the De Groots spotted Thanatotheristes didnt turn up any more bones, and recent flooding may have washed away whatever else remained.

Tyrannosaurus Rex

If Voris has his way, more specimens will join the ranks. He has plans of exploring the same rock formation in other parts of southern Alberta, in hopes of finding additional Thanatotheristes bones. Voris doesnt fear the reaper. If anything, he loves it.