The infamous Tyrannosaurus Rex – or T. rex – could weigh as much as 15,000 kg when it roamed the earth.
This is slightly more than the weight of two elephants, or a London double-decker bus, and is 70 percent more than previously believed.
Researchers at the Canadian Museum of Nature in Ottawa built a model that predicted the prehistoric beast’s maximum size.
So far, only 32 adult T. rex specimens have been discovered out of an estimated population of 2.5 billion.
The largest of these is “Scotty,” who weighed more than 19,400 pounds (8,800 kg) and stood more than 42 ft (13 m) tall when he roamed what is now the western side of North America between 68 and 66 million years ago.
However, researchers say the discovered specimens may not be an accurate representation of the species, and undiscovered individuals may have been much larger.

Tyrannosaurs rex (pictured) was a type of bird-like, carnivorous dinosaur. It lived between 68 and 66 million years ago in what is now the western side of North America
Paleontologists Jordan Mallon and Dr. Dave Hone first collected data on the population size and average lifespan of T. rex.
They used this data to build two models that predict the dinosaur’s typical growth curve over its lifetime.
One of these models assumed that the species exhibited sexual dimorphism in body size – with females and males growing to different weights – and the other did not.
Dr. Mallon told Live Science, “If T. rex were dimorphic, we estimate it would have weighed up to 24,000 kg, but we rejected that model because if it were true, we would have found even larger individuals by now.”
Earlier this year, another study claimed that T. rex could actually be three species, including T. regina, or the “queen of the dinosaurs,” and T. imperator.
However, this was later refuted by other scientists who said there was not enough evidence to split the iconic species.
Researchers presented their model and prediction about adult T. Rex body weight earlier this month at the annual meeting of the Society of Vertebrate Paleontology.
While Mr Mallon confirmed on Twitter that he is in the process of “tweaking” the final manuscript of this study, he also cautioned that the results are speculative until a specimen of this size is discovered.
He tweeted: ‘Our back-of-the-envelope calculations suggest that a 15,000 kg animal is mechanically feasible, but that requires more rigorous testing.’
“We’re talking about the equivalent of people being 6’9,” Dr. Hone added Twitter.

The largest dinosaur specimen ever discovered is ‘Scotty’ (pictured), who weighed more than 19,400 pounds (8,800 kg) and was over 40 feet (13 meters) long when alive
Research from last year revealed that humans could have outrun the T. Rex, as they enjoyed a “leisurely” walk at just 2.8 miles per hour (4.6 kph).
Scientists estimated the stride length of a T. Rex specimen named “Trix,” and reconstructed its tail to discover the rhythm in which it would swing.
Thus, the animal’s walking speed was comparable to that of emus, elephants, horses and humans.
Other studies have explored why the dinosaur had such small arms relative to its body.
For example, a 14m long T. rex might have had a skull 1.5m long, but arms only 1m long – the equivalent of a 1.8m human with 15cm arms.
One study suggests they evolved them to reduce the risk of being bitten by others hungry adult T. rex as they devour a carcass.
Another claims that dinosaurs with smaller front legs used them to grip each other during mating, or to help them get up after a fall.