GMA News Online

Dinosaurs were actually skinny, new research finds

June 6, 2012 7:45pm
Dinosaurs may not quite be the fat, lumbering and heavy creatures as they have been depicted in exhibits and movies for years.
A new study found these animals weighed less than previously estimated, according to a report on Discovery News.
“This is a huge help for any sort of reconstruction. We now have a number that suggests how much flesh to add to the bones and that should help people produce animals that are the right balance of too fat or too thin," lead author William Sellers told Discovery News.
Sellers, who is based at the University of Manchester’s Faculty of Life Sciences, added this technique can also allow one to calculate more sophisticated locomotor reconstructions, such as running simulations.
Citing some of the findings, the study said a huge Brachiosaur once thought to weigh 176,370 pounds is now believed to have weighed 50,706 pounds.
For the study, Sellers and his team used lasers to measure the minimum amount of skin required to wrap around the skeletons of large modern animals that included reindeer, polar bears, giraffes and elephants.
The researchers noticed that the animals had almost exactly 21 percent more body mass than the minimum skeletal “skin and bone” wrap volume.

About one-third the weight
Applying the formula to a giant Brachiosaur skeleton housed at Berlin’s Museum für Naturkunde, the team theorized the dinosaur’s weight, thought to have been as high as 176,370 pounds, may be just a svelte 50,706 pounds —about a third of of the original estimate.
“The 23 tonne weight (50,706 pounds) is quite low, but I think it reflects the fact that all dinosaur weights are getting lower,” Sellers said, adding the estimated weight for this dinosaur along with other species has been dropping since about the early 1960s.
He added the new estimate "reflects a better understanding of biology, and I think the early estimates were set in that big, fat and slow lizard mindset before the dinosaur renaissance."
"I think we will find that the lower estimates are much more appropriate for many dinosaurs,” he said.
Discovery News also noted high-tech scanners, fast computers and other tools were not available when dinosaur weights were first estimated.
Until fairly recently, even experts resorted to some fairly homespun methods for attempting to calculate dinosaur heft.
“One very common method is to take an artist’s reconstruction sculpture of the animal and measure its volume by dipping it in water just like Archimedes," Sellers said. "That gives you the volumes, which you can multiply by the density to get its weight.”
But he said the problem was the artist’s reconstruction, which he said is "very time consuming to do and probably rather inaccurate, so we thought we’d try a new method.”
Improved accuracy
Discovery News said the new method offers improved accuracy, and is minimally invasive and relatively quick.
For now, the main limitation is that the specimen should consist of a complete skeleton that has been mounted.
“This is reasonably accurate because the bones fit together like a jigsaw puzzle,” he said.
Heinrich Mallison of the Museum für Naturkunde told Discovery News that the new study describes “a brilliant approach: not trying to estimate soft tissues, but finding out how much a bone-only model underestimates the entire animal's mass.”
“(It is) certainly a very good method for mammals, but I'd like to see tests with more details to find out if archosaurs (crocodiles and dinosaurs) have the same regressions, or differ,” Mallison said. — TJD, GMA News
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