Massive dinosaur may have shared horse tendon trait

The largest known dinosaurs may have shared a nifty trait with horses in enabling the 80-tonne giants to stand.

Researchers suspect the Argentinosaurus, which roamed the earth 94 million years ago, may have had ligaments and tendons similar to those seen in horses.

A skeleton of Argentinosaurus dinosaur in Argentina. © Dr Bill Sellers
A skeleton of Argentinosaurus dinosaur in Argentina. © Dr Bill Sellers

“Horses have something known as stay mechanisms, a set of tendons and ligaments on limbs that are passive when the animal is just standing there,” said Dr Bill Sellers, lead researcher on the project from the University of Manchester’s Faculty of Life Sciences.

“It means a horse don’t have to activate muscles even though its legs aren’t straight. That sort of passive elastic support is probable [in Argentinosaurus], but we may never find evidence for that in the fossil record,” he said.

Sellers and his team digitally reconstructed the dinosaur, allowing it to take its first steps in over 94 million years.

The British team, working with scientists in Argentina, were able to laser-scan a 40 metre-long skeleton of the vast Cretaceous Argentinosaurus dinosaur.

Then, using an advanced computer modeling technique involving the equivalent of 30,000 desktop computers, they recreated its walking and running movements and tested its locomotion ability for the very first time.

The study, published in the open-access journal, PLoS ONE, provides the first “virtual” view of the dinosaur’s movement and disproves previous suggestions that the animal was inflated in size and could not have walked.

Sellers said: “If you want to work out how dinosaurs walked, the best approach is computer simulation. This is the only way of bringing together all the different strands of information we have on this dinosaur, so we can reconstruct how it once moved.”

Dr Lee Margetts, who also worked on the project, said: “We used the equivalent of 30,000 desktop computers to allow Argentinosaurus to take its first steps in over 94 million years.

“The new study clearly demonstrates the dinosaur was more than capable of strolling across the Cretaceous planes of what is now Patagonia, South America.”

The team of scientists included Dr Rodolfo Coria from Carmen Funes Museum, Plaza Huincal, Argentina, who was behind the first physical reconstruction of the dinosaur, which takes its name from the country where it was found.

Dr Phil Manning, from Manchester, who contributed to the paper, said: “It is frustrating there was so little of the original dinosaur fossilized, making any reconstruction difficult.

“The digitization of such vast dinosaur skeletons using laser scanners brings Walking with Dinosaurs to life … this is science not just animation.”

Sellers uses his own software, called Gaitsym, to investigate locomotion that both living and extinct animals have to overcome.

“The important thing is that these animals are not like any animal alive today and so we can’t just copy a modern animal,” he explained.

“Our machine learning system works purely from the information we have on the dinosaur and predicts the best possible movement patterns.”

The dinosaur weighed 80 tonnes and the simulation shows that it would have reached just over 2 metres pers second – about 5mph (8kmh).

Sellers said the research was important for understanding more about musculoskeletal systems and for developing robots.

“All vertebrates from humans to fish share the same basic muscles, bones and joints. To understand how these function we can compare how they are used in different animals, and the most interesting are often those at extremes.

“Argentinosaurus is the biggest animal that ever walked on the surface of the earth and understanding how it did this will tell us a lot about the maximum performance of the vertebrate musculoskeletal system. We need to know more about this to help understand how it functions in ourselves.

“Similarly, if we want to build better legged robots then we need to know more about the mechanics of legs in a whole range of animals and nothing has bigger, more powerful legs than Argentinosaurus.”

The University of Manchester team now plans to use the method to recreate the steps of other dinosaurs, including Triceratops, Brachiosaurus and Tyrannosaurus rex.

Sellers WI, Margetts L, Coria RA, Manning PL (2013) March of the Titans: The Locomotor Capabilities of Sauropod Dinosaurs. PLoS ONE 8(10): e78733. doi:10.1371/journal.pone.0078733

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