A Tyrannosaurus rex found in central Canada in the 1990s is the heaviest and oldest of its kind, paleontologists recently announced. The dinosaur, nicknamed Scotty, probably weighed about 9.8 tons and lived for more than three decades, they said. The results were published in a study last week in The Anatomical Record, a scientific journal, and posted online.

“This is the rarest of rare dinosaurs,” Gregory Erickson, a paleobiologist from Florida State University who was one of the study’s authors, said Wednesday. “We have a full, grown adult.”

Researchers estimated Scotty’s weight by measuring its hip, leg and shoulder bones, and comparing them to the skeletons of other T. rex specimens. The size and width of the femur bone suggest Scotty weighed 19,555 pounds, much larger than a male African elephant, which can grow to 14,000 pounds. In May, a new, updated cast of Scotty, which will reflect the scientists’ findings, will go on display at Royal Saskatchewan Museum in Regina, the capital of Saskatchewan.

Scotty was discovered in 1991 when an expedition of paleontologists to the Frenchman River Valley in Saskatchewan found a heavy worn tooth and vertebra from the tail of a T. rex, according to the museum. In 1994, they began excavating the site and found the bones and tooth fragments were dated to the Cretaceous Period and about 65 million years old.

It took nearly a decade to excavate the skeleton; analysis of the bones and teeth continued for several years. Scotty, the researchers learned, had a particularly rough life.

W. Scott Persons, a paleontologist from the University of Alberta in Canada who led the study, said Wednesday that the T. rex had broken bones, impacted teeth and bite marks, suggesting it had battled with other animals. Some of its wounds were infected. Persons said Scotty was probably in its early 30s when it died, outliving Sue, a T. rex discovered in South Dakota in 1990 that scientists estimate died at about 28. Sue has long been considered the largest skeleton found.

“It gives us a rare view of an elder T. rex,” Persons said. Scotty had cranial abnormalities, including bumps and ridges down its snout, which suggests it had armored skin. “It had flare to its face,” he said.

Despite its name, paleontologists are not sure of the T. rex’s gender. Erickson said Scotty was named after the Scotch researchers drank to celebrate their great find.

On Wednesday, the researchers could barely contain their delight. “There is so much negativity in the world,” Erickson said. “But this is neutral. It’s just fun.”

This article originally appeared in The New York Times.