Some 66 million years ago, a Tyrannosaurus rex weighing an estimated 19,555 pounds—nearly as much as four pick-up trucks—roamed what is now the Canadian province of Saskatchewan. Measuring roughly 42 feet long, the dinosaur led what University of Alberta paleontologist Scott Persons describes as an “unusually long” but violent life, enduring injuries ranging from broken ribs to an infected jaw before dying in its early 30s.
Researchers first unearthed the formidable T. rex’s remains in 1991, Michael Greshko reports for National Geographic. Given the dinosaur’s sheer size and encasement in cement-like sandstone, however, it took more than two decades to fully excavate and analyze the bones. Luckily, the paleontologists behind the find write in the Anatomical Record, the results were worth the wait: Not only is the T. rex, nicknamed “Scotty” in honor of a celebratory toast of scotch raised upon its discovery, the biggest member of its species ever found, but it also holds the distinction of being the longest-lived T. rex identified in the fossil record to date.
"This is the rex of rexes," study lead author Persons observes 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.”
To gauge Scotty’s size, Persons and his colleagues measured its leg, hip and shoulder bones. According to Gizmodo’s George Dvorsky, although the dinosaur’s skeleton is only 65 percent complete, the team was able to estimate its body mass by using the circumference of the femur to calculate the amount of weight the legs could withstand.
Compared to 11 similarly well-preserved T. rex skeletons, Scotty appears to have the advantage in terms of pure mass, if not height and overall length. Sue, a dinosaur unearthed in 1990 and the previous biggest T. rex record holder, weighed an estimated 18,651 pounds, or some five percent lighter than the new heavyweight title winner.