T. Rex may have weighed up to 33,000 pounds

Scientists have long known that Tyrannosaurus Rex was one of the largest and most fierce dinosaurs that even roamed the Earth. However, how big this ferocious predator was remained a matter of scientific debate. Now, a team of researchers led by the Canadian Museum of Nature in Ottawa, Ontario has estimated that the largest T. rex may have weighted a staggering 33,000 pounds (15,000 kilograms), making it heavier than an average school bus of about 24,000 pounds (11,000 kilograms).

At the moment, the largest Tyrannosaurus rex on record is a specimen called “Scotty” that most likely weighed 19,555 pounds (8,870 kg) when it was alive – about as much as 6.5 Volkswagen Beetles. According to the new estimates though, the largest T. rex would have been 70 precent larger Scotty.

To reach this conclusion, the researchers first examined the fossil record, which suggests that about 2.5 billion T. rexes once roamed the Earth. However, only a small fraction of these dinosaurs (about 32 adult fossils) has ever been discovered, thus providing the scientists with a very limited amount of information to draw from.

Yet, by looking at population numbers, average lifespans, and variations in body size based on sexual dimorphism (the differences in size between the sexes of animals from the same species), the experts managed to model T. rex’s growth curve throughout its lifetime and estimate how an adult might have grown.

“We wound up building two models — one exhibiting zero dimorphisms and one with strong dimorphism,” explained study co-author Jordan Mallon said, a paleobiologist at the Canadian Museum of Nature. “If T. rex was dimorphic, we estimate that it would have weighed up to 53,000 pounds (24,000 kg), but we rejected that model because if it were true, we would have found even larger individuals by now.”

However, the researchers warned that until a Tyrannosaurus Rex fossil comparable in size to the one in the model is found, their estimations remain purely speculative. “This is simply a thought experiment with some numbers behind it. It’s something that’s fun to think about,” Mallon said.

“This reminds us that what we know about dinosaurs isn’t much at all, since the sample sizes are so small,” said Thomas Carr, a vertebrate paleontologist from the Carthage College in Kenosha, Wisconsin, who was not involved in the study. “Right now, we are nowhere near the sample size needed, especially when compared to other species of animals.”

The study was presented on November 5 at the Society of Vertebrate Paleontology’s annual congress in Toronto, Canada.     

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By Andrei Ionescu, Earth.com Staff Writer

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