The world’s biggest known Tyrannosaurus rex lived in prehistoric Saskatchewan 66 million years ago and measured 13 metres, according to University of Alberta paleontologists.

“This is the rex of rexes,” said Scott Persons, a U of A paleontologist who led a study on the once formidable dinosaur, nicknamed Scotty.

“There is considerable size variability among Tyrannosaurus. Some individuals were lankier than others and some were more robust. Scotty exemplifies the robust. (He) comes out a bit heftier than other T. rex specimens.”

Nicknamed for a celebratory bottle of scotch the night it was discovered, Scotty has leg bones suggesting a living weight of more than 8,800 kilograms, making it bigger than all other carnivorous dinosaurs.

The skeleton was first discovered in 1991. The bones were encased in sandstone, which took more than a decade to remove. It’s only recently, after several more years piecing together the specimen like a jigsaw puzzle, that scientists have been able to study Scotty.

Long lived the king

Scotty’s size and weight aren’t all that set it apart, Persons noted—the Canadian mega-rex also lays claim to seniority.

“Scotty is the oldest T. rex known,” Persons explained. “By which I mean, it would have had the most candles on its last birthday cake. You can get an idea of how old a dinosaur is by cutting into its bones and studying its growth patterns. Scotty is all old growth.”

But age is relative, and T. rexes grew fast and died young. Scotty was estimated to have been in its early 30s when it died.

“By Tyrannosaurus standards, it had an unusually long life. And it was a violent one,” Persons said. “Riddled across the skeleton are pathologies—spots where scarred bone records large injuries.”

Among Scotty’s injuries are broken ribs, an infected jaw and what may be a bite from another T. rex on its tail—battle scars from a long life.

”I think there will always be bigger discoveries to be made,” said Persons. “But as of right now, this particular Tyrannosaurus is the largest terrestrial predator known to science.”

A new exhibit featuring the skeleton of Scotty is set to open at the Royal Saskatchewan Museum in May 2019.

The study, “An Older and Exceptionally Large Adult Specimen of Tyrannosaurus rex,” was published in The Anatomical Record.