Dinosaurs Weight Less Than Previous Estimates

Despite their onscreen presence in movies such as Jurassic Park as huge, lumbering goliaths, new research shows that they may have been skinnier than previously thought.

By using a special technique to calculate the minimum skeletal 'skin and bone' wrap volume, researchers looked at large modern-day mammals such as polar bears, giraffes, and elephants.  What they found was that the 'skin and bone' wrap volume was consistently 21 percent under the actual body mass.

The scientists then applied the laser scanning to the giant Brachiosaur skeleton in Berlin's Museum für Naturkunde and were able to estimate that the Brachiosaurus weighed around 50,000 pounds - far less than the previous estimates of up to 175,000 pounds.

"We showed that the actual volume is reliably 21 percent more than this value, so we then laser scanned the Berlin Brachiosaur, Giraffatitan brancai, calculating the skin and bone wrapping volume and added 21%. We found that the giant herbivore weighed 23 tons, supporting the view that these animals were much lighter than traditionally thought," said lead author of the paper Dr. Bill Sellers.

Body mass is an important characteristic that scientists use to approximate the behavior and metabolic functions of an animal. The data is even more important when those animals do not exist anymore, and scientists need to piece together its lifestyle from fossils.

"Volumetric methods are becoming more common as techniques for estimating the body masses of fossil vertebrates but they are often accused of excessive subjective input when estimating the thickness of missing soft tissue," said Sellers.

"Here, we demonstrate an alternative approach where a minimum convex hull is derived mathematically from the point cloud generated by laser-scanning mounted skeletons. This has the advantage of requiring minimal user intervention and is therefore more objective and far quicker."