World's most complete Stegosaurus weighed 1,600kg

The world's most complete specimen of a Stegosaurus dinosaur dating back to 150 million years weighed 1,600kg, equivalent to a small rhino, researchers have found.
The researchers from Imperial College London and the Natural History Museum calculated the body mass of the extinct creature to get an accurate measurement.
They used this approach on a Stegosaurus skeleton nicknamed Sophie, which was found in Wyoming in the US in 2003. They have calculated that Sophie would have weighed around 1,600 kg, similar in weight to a small rhino.
"Although the Stegosaurus is something of an iconic dinosaur, scientists know very little about its biology because its fossils are surprisingly rare," Dr Susannah Maidment, Junior Research Fellow from the Department of Earth Science and Engineering at Imperial College London, said.

"We don't actually know whether Sophie was female or male, despite its nickname. When it died, Sophie was a young adult - equivalent to a human teenager.
"Although there is no evidence for why it died, it seems that the carcass fell into a shallow pond, where it was quickly buried, preventing other animals from scavenging it, and explaining why it is so well preserved," said Maidment.

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

"Because this incredible specimen is so complete, we have been able to create a 3D 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," Dr Charlotte Brassey, palaeontologist from the Museum and lead author of the study, added.
"We also took the skeleton's leg bone circumference and compared it to a modern animal of similar size, and came up with matching estimates for the dinosaur's weight," said Brassey.
The scientists discovered the body mass of this dinosaur by fitting simple shapes to the digital skeleton and calculating its volume.

They then converted this into body mass using data collected from similar modern animals. When compared to figures calculated using the sole method of measuring leg bone circumference in conjunction with the overall weight of various living animals, the results are in close agreement.
Both techniques produced an estimate of 1600 kg and, combined, are now considered the most accurate way of measuring the body weight of nearly complete fossil skeletons.
The research was published in the journal Biology Letters.