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Dinosaurs Nearly 75% Lighter Than Previously Thought - But They're Still Pretty Big

Steven Spielberg’s Jurassic Park is famous for the scene where a puddle of water ripples as a Tyrannosaurus Rex approaches – but the director may need to re-edit this with smaller ripples, because it turns out that dinosaurs are far lighter than previously thought.

The revelation comes from University of Manchester biologists, who developed a new technique to accurately measure the weight and size of dinosaurs.

They began by using lasers to measure the minimum amount of skin required to wrap around the skeletons of modern-day mammals, including reindeer, polar bears, giraffes and elephants.

Light-weight: The Brachiosaur in Berlin's Museum für Naturkunde

They discovered that the animals had almost exactly 21 per cent more body mass than the minimum skeletal ‘skin and bone' wrap volume, and applied this to a giant Brachiosaur skeleton in Berlin's Museum für Naturkunde.

Previous estimates of this Brachiosaur's weight have varied, with estimates as high as 80 tonnes, but the Manchester team's calculations – published in the journal Biology Letters – reduced that figure to just 23 tonnes. The team says the new technique will apply to all dinosaur weight measurements.

Lead author Dr Bill Sellers said: "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.

Hi-tech: The researchers used lasers to work out how much skin was needed to cover the dinosaur

“We laser scanned various large mammal skeletons, including polar bear, giraffe and elephant, and calculated the minimum wrapping volume of the main skeletal sections.

"We showed that the actual volume is reliably 21 per cent more than this value, so we then laser scanned the Berlin Brachiosaur, Giraffatitan brancai, calculating the skin and bone wrapping volume and added 21 per cent. We found that the giant herbivore weighed 23 tonnes, supporting the view that these animals were much lighter than traditionally thought.”

He added that dinosaurs were still huge, though.

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