The world’s biggest known Tyrannosaurus rex — one of the largest and most fearsome carnivores of all time — lived about 66 million years ago (Cretaceous period) in what is now Saskatchewan, Canada.

Scotty was 42.7 feet (13 m) long and weighed approximately 8,870 kg.

The large, relatively complete (roughly 65%) skeleton was found in a layer of the Frenchman Formation near Eastend, Saskatchewan, in 1991.

The bones were encased in iron-stained, heavily-cemented 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 paleontologists have been able to study the specimen.

“This is the rex of rexes,” said Dr. Scott Persons IV, a paleontologist in the Department of Biological Sciences at the University of Alberta.

“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.”

“Scotty is the oldest T. rex known,” said Dr. Persons, first author of a paper published in the journal Anatomical Record.

“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,” Dr. 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. But as of right now, this particular Tyrannosaurus is the largest terrestrial predator known to science,” Dr. Persons said.

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W. Scott Persons IV et al. An Older and Exceptionally Large Adult Specimen of Tyrannosaurus rex. Anatomical Record, published online March 21, 2019; doi: 10.1002/ar.24118