London: Tyrannosaurus rex, the largest known land carnivores of all time, was even heavier and fiercer than previously thought, researchers have claimed.
Using advanced technology to weigh models of the giant beast that roamed the Earth some 65 million years ago, experts found that it could get to a weight of nine tonnes, 30 percent more than previously thought, and grew twice as fast.
The study, published in the journal PLoS One, was carried by a team of scientists led by Professor John Hutchinson of The Royal Veterinary College, London, and Peter Makovicky of The Field Museum of Natural History in Chicago.
The researchers used lasers to create ultra-accurate 3D scans of dinosaur skeletons, including the `SUE` skeleton at Chicago`s Field Museum. Then they "modelled" flesh for the beasts using the soft tissue-to-skeleton ratios of birds and crocodiles as a guide, the Daily Mail reported.
Digital body cross-sections were reconstructed along the length of each skeleton using the relationships of the soft tissues to skeletons in birds and crocodiles as a guide.
A digital skin was then overlaid to generate a body volume, whose mass was calculated after empty spaces such as lungs and the mouth cavity were modelled and subtracted.
In order to appreciate the uncertainty involved in estimating how much flesh would wrap the skeleton of an extinct animal, body sections were modelled individually at three levels of "fleshiness".
The three versions of each body segment were combined in different ways to generate a range of whole body models with varying masses.
"Nine tonnes is the minimum estimate we arrived at using a very skinny body form, so even if we made the chest smaller, adding a more realistic amount of flesh would make up for the weight," said Makovicky.
According to Makovicky, this method provided more accuracy than previous methods which relied on scale models.
"The scale models magnify even minor errors, or on extrapolations from living animals with very different body plans from dinosaurs. We overcame such problems by using the actual skeletons as a starting point for our study," he said.
SUE was also larger than the other specimens when individual body segments were compared, but Makovicky is not surprised by that result.
"We often hear about new T. rex discoveries that rival SUE in some select measurement, but body size is a 3-D parameter and SUE is much more robust than other known skeletons," he said.
The weight estimates also alter understanding of T-rex biology. The higher mass estimates for the larger specimens and a lower one for the smallest individual indicate even faster growth than was proposed in a landmark study just five years ago, the researchers said.