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Young stegosaurus weighed 3,527 pounds

Understanding an ancient animal's weight (and weight distribution) can help researchers better predict how it may have moved.

By Brooks Hays
Computer-generated 3-D model for young stegosaurus. Photo by National History Museum
Computer-generated 3-D model for young stegosaurus. Photo by National History Museum

LONDON, March 4 (UPI) -- Scientists have estimated the weight of young stegosaurus specimen recently acquired by the London's Natural History Museum. Still only a juvenile when it died, the plated dino weighed an incredible 3,527 pounds.

The stegosaurus specimen, nicknamed Sophie, boasts 80 percent of its bones -- the most complete and well-preserved skeleton of its kind.

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"Because this incredible specimen is so complete, we have been able to create a 3-D digital model of the whole fossil and each of its 360 bones, which we can research in excellent detail without using any of the original bones," Charlotte Brassey, museum scientists, said in a press release.

Brassey and colleague Paul Barrett, with the help Susannah Maidment of Imperial College London, averaged the results of their model and a more traditional weight formula to estimate the dino's tonnage.

The new technique worked by shaping geometrical figures around the bones in the 3-D digital model. Researchers then used mass-to-volume ratios from modern animals to estimate the weights of these geometrical figures. Add them all up and you have the animal's total mass.

A more traditional method, relying solely on the circumference of the animal's femur (thigh bone) and humerus (upper arm), put the young dino's weight at almost twice that of the 3-D model's total. But scientists suggest the adolescent dinosaur, who likely died at age seven or eight, possessed leg bones which were growing at a faster rate than the rest of its body.

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Understanding an ancient animal's weight (and weight distribution) can help researchers better predict how it may have moved -- allowing researchers to model its gait or determine how fast it ran. These details are especially important for studying dinosaurs like Sophie, as the movements of modern animals aren't very useful for extrapolating the movements of these long-extinct species.

"Dinosaurs are related to modern birds and crocodiles, but their anatomy could have been quite different in some cases," said Brassey. "The main muscles that would be used to pull the hind limbs backwards would have been pretty large and would have attached quite far down the tail."

"Combined with its wide hips, it's fair to say this Stegosaurus probably would have had quite a large rear end," she added.

The research into Sophie's weight was detailed this week in the journal Biology Letters.

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