Sophie the Stegosaurus is one of the most complete fossils of its type anywhere in the world, and now researchers have found a method to calculate the mass of the ancient animal.

The stegosaurus fossil was discovered on the Red Canyon Ranch in Wyoming in 2003. The fossil was sent to the Natural History Museum in London in 2013, and digital scans were taken of the 360 fossilized bones recovered from the animal, before the skeleton went on public display in 2014.

Digital recreations of muscles, skin and other body features were added to the virtual model of the bones. Simple geometric shapes were then fitted to sections of the model, in order to calculate the volume of the creature. From this information, investigators calculated the ancient creature weighed over 3,500 pounds, about the same as a contemporary rhinoceros.

Dinosaurs in the stegosaurus genus lived from 155 to 150 million years ago, roaming lands in western North America. These animals, marked by plates running down the length of their backs, were herbivores.

Measuring the mass of Sophie could allow researchers to learn more about the genus, as well as other dinosaurs. Paleontologists want to know how the animals walked, and how much they ate to support their daily activities. This new study could help answer both questions.

"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," Paul Barrett, lead dinosaur researcher at the Natural History Museum, said.

The circumference of bones was measured, and compared to modern-day species, allowing researchers to calculate weight using an independent method. Each technique produced similar results, suggesting the new technique is likely an accurate way of calculating the mass of long-dead creatures.

Paleontologist Othniel Charles Marsh discovered the first of these fossils in 1877, during an expedition north of Morrison, Colorado.

Sophie was an adolescent animal when she perished, although the means of her death is unknown to researchers. She may have fallen into a shallow pond, and was quickly buried in sediment, protecting the carcass from scavengers and natural damage. Despite the name, scientists are uncertain whether the animal was male or female.

"Although the Stegosaurus is something of an iconic dinosaur, scientists know very little about its biology because its fossils are surprisingly rare," Susannah Maidment of Imperial College London stated in a university press release.

Development of the new technique to measure body mass of dinosaurs, and calculation of the weight of Sophie, was profiled in the The Royal Society journal Biology Letters.

Photo: Jay Malone | Flickr

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