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​What did Stegosaurus weigh? Now we know

Researchers at London's Natural History Museum used 3D modeling to figure out the mass of its prize Stegosaurus skeleton, the world's most complete specimen.

The 150-million-year-old skeleton was unearthed in Wyoming in 2003 and brought to London in December 2013. Scientists there assembled the 360 bones that make up the 18-foot-long, 9.5-foot-tall stegosaur, then imaged them with laser and CT scans and 360-degree photographs to create an accurate 3D model.

From that, they extrapolated the overall size and shape of the young adult dinosaur to calculate its volume, which they compared to modern animals of known size to estimate its weight. They then used another approach to come up with a second estimate, measuring the circumference of the skeleton's leg bones and lining that up against the corresponding masses of animals with similarly sized leg bones.

3D model of the Natural History Museum's Stegosaurs skeleton Natural History Museum, London

Both methods yielded the same result: 1,600 kilograms (3,530 pounds). That's about the size of a small rhino. Or 176 dachshunds. Or four people riding in a Honda Civic.

"These findings identify just how important exceptionally complete specimens like this are for scientific research and collections," said professor Paul Barrett, lead dinosaur researcher at the Natural History Museum. "Now we know the weight, we can start to find out more about its metabolism, feeding requirements and the growth rates of Stegosaurus. We can also use the same techniques on other complete fossils to find out much more about the wider ecology of dinosaurs."

The modeling also revealed to the researchers that this particular stegosaur "probably would have had quite a large rear end."