T Rex Bigger Than Previously Thought
October 13, 2011

T Rex Bigger Than Previously Thought

Researchers said on Wednesday that the Tyrannosaurus rex grew faster and weighed more than previously thought.

British and U.S. scientists used three-dimensional laser scans and computer modeling to "weigh" five T. rex specimens, including Chicago Field Museum's famous "Sue".

"These models range from the severely undernourished through the overly obese, but they are purposely chosen extremes that bound biologically realistic values" study co-author Dr. Vivian Allen of the Royal Veterinary College said in a press release.

The researchers found that Sue would have tipped the scales at more than 9 tons, which is about 30 percent more than previous estimates.

The smallest and youngest specimen the scientists researched weighed less than previously thought though, which indicates that T. rex grew more than twice as fast between 10 and 15 years of age.

The researchers modeled body sections of the specimens at three levels of "fleshiness" in order to help understand how much flesh would wrap around the skeleton of an extinct animal.

The three version of each body segment were combined in different ways to generate a range of whole body models with varying masses.

"The real advantage to our method is that the models can be adjusted to accommodate the variation that is inherent in nature, so we don't have to pick an arbitrary result, but rather deal with more meaningful ranges of results," co-author Dr. Karl T. Bates of the University of Liverpool said in a press release.

The fleshier models for Sue ranged even higher in body mass, which could have been the result of how the skeleton was reconstructed.

"Sue's vertebrae were compressed by 65 million years of fossilization, which forced a more barrel-chested reconstruction" Peter Makovicky, PhD, curator of dinosaurs at The Field Museum of Natural History in Chicago, said in a press release. "Nine tons 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."

The new mass estimates alter scientists' understanding of T. rex biology.  The higher mass estimates for the larger specimens and a lower one for the smallest individual indicate a faster growth than was proposed in a study five years ago.

The researchers estimate that T. rex grew as fast as 3,950 pounds per year during the teenage period of growth, which is more than twice the previous estimate.

The study was published in the journal PLoS One.


Image 1: Close up of "Sue" T-Rex replica skull at the Field Museum of Natural History in Chicago, IL. Credit: ScottRobertAnselmo/Wikipedia (CC BY-SA 3.0)  

Image 2: Scale 3D model of a fully grown 9 ton adult T rex, a “juvenile“ T rex and a fully grown human. Credit: Royal Veterinary College


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