About 66 million years ago, the fossil — nicknamed “Scotty” — belonged to a 42-foot-long Tyrannosaurus roaming prehistoric Saskatchewan. When researchers studied the leg bones, they found that the dinosaur probably weighed in at about 9.7 tons. That makes this Tyrannosaurus bigger than any other carnivorous dinosaur.
The study was published last week in The Anatomical Record.
“This is the rex of rexes,” Scott Persons, lead author of the study and a postdoctoral researcher in the University of Alberta’s Department of Biological Sciences, said in a statement. “There is considerable size variability among Tyrannosaurus. Some individuals were lankier than others and some were more robust. Scotty exemplifies the robust. Take careful measurements of its legs, hips, and even shoulder, and Scotty comes out a bit heftier than other T. rex specimens.”
Scotty has quite a history, and he wasn’t dug out of the ground recently. Rather, the fossil was discovered in 1991, but his bones were locked in hard sandstone. It took more than a decade to remove the stone, fully assemble the fossil and study Scotty to realize how different he was from other T. rex fossils.
The nickname comes from the celebratory scotch that was imbibed on the night the fossil was discovered.
“Scotty is the oldest T. rex known,” Persons said. “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.”
T. rexes weren’t known for living long. They were quick to grow and often died young. Scotty was in his early 30s when he died, and he carried the battle scars to show how hard he fought to live.
Researchers cataloged the injuries recorded on his bones and discovered an infected jaw, broken ribs and what looks to be a bite from a fellow T. rex on his tail.
“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.”
If you want to see Scotty for yourself, the impressive fossil will be on display in a new exhibit at the Royal Saskatchewan Museum beginning in May.
“I think there will always be bigger discoveries to be made,” Persons said. “But as of right now, this particular Tyrannosaurus is the largest terrestrial predator known to science.”