Dinosaurs were almost 75% lighter than we previously thought
"He's not fat, he's just big boned!" That old excuse may actually apply when it comes to dinosaurs.
Based on their skeletons, scientists previously estimated that the Brachiosaur, a long-necked dinosaur common in the Jurrassic era, weighed as much as 80,000 pounds, but it turns out these monstrous creatures didn't tip the scales quite that much.
"One of the most important things palaeobiologists need to know about fossilised animals is how much they weighed. This is surprisingly difficult, so we have been testing a new approach," said study author Bill Sellers.
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Until now, measuring a dinosaur's weight could be done in one of two ways, according to Discover Magazine. Scientists compare the length of certain bones to those of known animals and scale up to get a general guess of the dinosaur's weight. Or they take an outline of the body, estimate the volume it takes up, and multiply that with a predicted density. Neither approach is particularly accurate, but Seller's team has devised a much less labor-intensive third option.
Using lasers to measure the minimum amount of skin required to wrap about the skins of modern-day mammals, University of Manchester biologists created a weight-measurement technique that they then applied to dinosaurs.
They discovered that current-day mammals - such as polar bears, reindeer, giraffes and elephants - have almost exactly 21 percent more body mass than the minimum skin needed to wrap around their skeletons.
They then used their calculations on the world's largest mounted dinosaur skeleton, a giant Brachiosaur skeleton in Berlin's Museum für Naturkunde, and found that their method reduced the dino's actual weight to just 23 tons. That's close to half the highest earlier estimates of the giant herbivore's weight.
"Our method provides a much more accurate measure and shows dinosaurs, while still huge, are not as big as previously thought," says Sellers.
The team says their method, which will be published in the journal Biology Letters, will apply to all other dinosaurs.
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