Quirks & Quarks

Big, old and banged-up — Canada is home to the world's largest Tyrannosaurus Rex

A dinosaur discovered more than two and a half decades ago has finally been extracted from the rock it was buried in, so that paleontologists could see how big it was in life.

It took nearly 20 years to extract the huge dinosaur from the rock it was embedded in

Saskatchewan’s Scotty has officially dethroned Chicago's Sue as the biggest Tyrannosaurus Rex ever found. (Amanda Kelley)

A dinosaur discovered more than two and a half decades ago has finally been extracted from the rock it was buried in, so that paleontologists could see how big it was in life. The Tyrannosaurus Rex nicknamed Scotty turns out to be the largest and oldest ever found.

Scotty is estimated to have weighed in the vicinity of 8,800 kilograms when it died at the age of about 30, making it the most massive and eldest T.rex.

Scotty's skeleton was found in Saskatchewan in 1991, but it wasn't until 2014 that painstaking work finally extracted it from the hard, iron-laced sandstone that protected it for more than 66 million years.

"Many of the early years were spent getting Scotty out of the ground and into the collections of the Royal Saskatchewan Museum, and even then there were a lot of work to be done on it" said Scott Persons in conversation with Bob McDonald on Quirks & Quarks.

Persons is a paleontologist from the University of Alberta and the lead author on the study looking into Scotty's size.

Scotty was named after the scotch whisky used to celebrate its discovery, says Persons, and the name they share is just a coincidence.

A seriously sturdy predator

The previous size record holder for T.rex size is Sue, the massive fossil at the Field Museum in Chicago, but Scotty is estimated to have outweighed her by about 400 kilograms.

University of Alberta paleontologist Scott Persons measures Scotty's jaw. (Amanda Kelley)

While Scotty might have weighed a bit more, it doesn't necessarily mean Scotty is the longest or tallest, said Persons.

"Scotty represents the most massive and that's because it's got sort of a stocky build." There's variation in tyrannosaur proportions, he explained, "some longer and lankier than others."

Scotty wasn't just the largest, it was the oldest

To figure out Scotty's age, a team of paleontologists used bone histology, a technique that analyzes thin sections of bone to look at its internal structure.

"As dinosaurs grew, they laid down new layers of bone to the outer walls, so looking at them in cross-section you can almost see the equivalent of tree rings — lines of annual growth," said Persons. 

"Scotty's so old it's gotten to the point that it was basically done adding on new layers of bone to the outside and instead was remodeling its existing skeleton."

By comparing Scotty's bone to other tyrannosaurs, the team estimated Scotty's age at about 30, which makes it a senior citizen by T.rex standards.

With the long life comes battle scars

Scotty's bones have many pathologies — places where scars or damaged bone records things like infection or injury. 

The team found signs of an infected jaw and an impacted tooth, and various injuries possibly related to the violent encounters it would have had with the large herbivorous dinosaurs it would have hunted.

One notable injury was a section of its tail where the vertebrae were strongly compressed. Persons speculates that this might have been from a bite by another tyrannosaur.

Clearly Scotty led a hard and violent life, and Persons can only speculate that its bulk might have been what ultimately allowed it to live such a comparatively long life. 

"It's an individual of extreme size and maybe that helped edge out it's competition," he said.


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