We knew that Tyrannosaurus rex were huge. We now have reason to believe they were 70% even larger

A few years ago, in August 1991, a group of paleontologists unearthed in Saskatchewan, Canada, a mass of bones from what appeared to be a dinosaur that had lived at the end of the Cretaceous. The discovery excited them so much that it is said that that same night the expedition celebrated it by toasting it with a good Scotch whiskey. In a nod to that celebration, today the prehistoric creature is known inside and outside of Canada as “Scotty”.

They had reasons for doing so: the vestiges of the Frenchman River Valley belonged, as would be confirmed years later, in 2019, to the largest Tyrannosaurus rex (T-rex) ever discovered.

Reaching that conclusion took time because Scotty’s bones were trapped in hard sandstone, which lengthened the painstaking work of removing the stones, assembling all the remains, and then studying them by comparing them with other similar fossils. The effort was considerable, but it was worth it. Before paleontologists it took shape “el rex de rexes”as Soctt Person, a researcher in the Department of Biological Sciences at the University of Alberta, joked at the time.

Puns aside, Scotty certainly stood out for his enormous dimensions.

Studies revealed that when roaming the valleys of what is now Saskatchewan, the old T-rex weighed about 8.870 kgconsiderably longer than an African elephant, and was 12 meters long. Seen in the museum it could be fascinating. Finding yourself in front of its open maw 66 million years ago was, however, an experience that few creatures would want to live.

What if Scotty was average?

Now, three decades after Scotty’s discovery, we have indications to think that although the Canadian T-rex was huge, at least by the parameters we are used to handling, perhaps it was not so huge among its peers. What’s more, the calculations with the information we have today have allowed us to ask ourselves a question that points in a very different direction: What if that Scotty that has been fascinating us—and terrifying us—for years was actually a really crazy T-rex? more normal, far, very far, from the enormous dimensions reached by other specimens?

That is the question that a team of experts from the Society of Vertebrate Paleontology has been defending for some time. Two years ago, Jordan Mallon, a researcher at the Twitter.com/MuseumofNature”>Canadian Museum of Natureand David Hone, from Queen Mary University of London, presented a theoretical exercise which has led to a fascinating conclusion: the T-rex could have reached dimensions much higher than what we believed until now.

Their estimates specifically suggest that the largest T-rex could reach the 15,000 kilogramsmuch more than an 11,000 kilo school bus. The data would be 70% more than what the fossils we have and what the bones of old Scotty tell us suggest. “That almost doubles the size of T-rex,” Mallon explained to the publication Live Science.

For their calculations, the scientists started from the fossil record and a striking fact: it is estimated that 2.5 billion Tyrannosaurus Rex roamed the Earth, a more than considerable number of specimens that moved for 127,000 generations. Despite that figure, the reality is that we only handle a few dozen adult fossils: 32, to be more precise, according to calculations published in 2021 in Nature. The figure is equivalent to only one in every 80 million T-rex. Bit. Very little. And, of course, that limits our own ability to know them.

Mallon and Hone built on that basis and analyzed population figures and average life expectancy to create a T-rex model. “as big as possible”according to Live Science.

During their research they took into account possible variations based on sexual dimorphism, the phenomenon that explains why lions and lionesses or roosters and chickens are so different. Taking this factor into account and assuming that Tyrannosaurus rex was dimorphic, their model indicated that it could reach 24,000 kilograms, a possibility that they ended up ruling out because — Mallon acknowledges — if it were true, scientists would have already found larger individuals.

The other model, without dimorphism, did allow them to model a growth curve throughout the dinosaur’s life and estimate what dimensions it could have reached as an adult. The team recognizes in any case that at the moment, and waiting to unearth fossils that corroborate their calculations, what they manage is only “a thought experiment with some numbers behind.”

“This reminds us that what we know about dinosaurs is not much, since the sample sizes are very small,” Thomas Carr, a scientist at Carthage College, who did not participate in the research, but did attend, acknowledges to the WoerdsSidekick website. the lecture given during the Society of Vertebrate Paleontology (SPV) conference: “At this point, we are nowhere near the necessary sample size, especially compared to other species.”

Image | Brett Meliti

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*An earlier version of this article was published in November 2022