gpronger writes "Researchers John Hutchinson (Royal Veterinary College in London) and Peter Makovicky (Field Museum of Natural History, Chicago) built digital models of a T-Rex and then added flesh using the structure of soft tissues in birds and crocodiles as a guide. This allowed them to project body mass. By doing this for a number of specimens of different age and size, they could also evaluate growth. At maximum, the adolescents could add 11 pounds in weight in a single day. The adult was found to be 30% heavier than earlier estimates, at more than 9 tons. With this size and appetite, they would need a large range, and therefore also be relatively rare in the ecosystem of the time."