|The computer models of the tyrannosaur skeletons|
Makovichy's unique work place in Chicago meant that the team were able to use the prized Chicago specimen 'Sue,' which is one of the most complete and largest tyrannosaur fossils ever found. Makovicky stated, 'previous methods for calculating mass relied on scale models, which can 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.'
By constructing 3D computer models from detailed laser scans of the skeletons, the scientists were able to place soft tissues onto the bones by using the relationships of the muscle tissues in birds and crocodiles. Finally they added a layer of flesh and fat and subtracted the empty cavities of the stomach and lungs. The final models covered a range of sizes from the skinny to the incredibly obese. The study took into account the fact that the fossil bones were compressed for the millions of years they had spent in the Earth.
Previous models displayed such creatures as having rather stocky chests. These new models show that the tyrannosaurids were larger and grew far faster, at around 1790 kilograms per year, than scientists originally thought. Of course these new figures mean that it would have been slower and less nimble than most other predators of the time.'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,' adds co-author Dr. Karl T. Bates of the University of Liverpool.