This Dinosaur Had a 50-Foot-Long Neck, Scientists Say

They compared vertebrae discovered in 1987 to more complete remains to make this new estimate

A rendering of long-necked Mamenchisaurus sinocanadorum dinosaurs
A rendering of Mamenchisaurus sinocanadorum dinosaurs with their 50-foot-long necks. Júlia d’Oliveira

A dinosaur that roamed East Asia 162 million years ago had an impressive, 50-foot-long neck, according to a new paper published Wednesday in the Journal of Systematic Paleontology.

The creature, called Mamenchisaurus sinocanadorum, belonged to a group called sauropods. These large, plant-eating dinosaurs are known for their lengthy necks and tails—but, according to the scientists’ estimate, Mamenchisaurus had the longest neck of them all.

Researchers uncovered the dinosaur’s fossilized remains in China in 1987, but they didn’t have much of the creature to study—only a few bones, including some vertebrae and a rib, writes New Scientist’s Chris Stokel-Walker.

Still, the scientists estimated the length of the dinosaur’s neck by comparing the limited evidence to more complete skeletons of its relatives. They looked at the 44-foot-long neck of a sauropod called Xinjiangtitan, which was discovered in 2013 and is the longest complete neck ever found, according to the New York Times Jack Tamisiea.

“Our analyses make us fairly confident that Mamenchisaurus sinocanadorum had 18 vertebrae in its neck, because close cousins known from more complete skeletons all have 18 cervical vertebrae,” Andrew Moore, a co-author of the study and a paleontologist at Stony Brook University, told Live Science’s Laura Geggel in an email. “So, focusing just on these close relatives with similar necks, we scaled up.”

The researchers determined that the Mamenchisaurus neck was approximately 49.5 feet long, per a statement. Such a length would have come in handy for foraging—the creatures could efficiently graze large amounts of vegetation, Moore tells Live Science.

“The long necks of these animals are amazing, even by dinosaur standards,” David Hone, a paleontologist who studies dinosaurs at Queen Mary University of London and was not involved in the research, tells New Scientist. “Understanding their evolution is really important to see how these animals lived.”

The dinosaurs evolved a few ways to manage their unwieldy necks. Researchers used CT scans to find that most of the vertebrae’s volume—about 69 to 77 percent—was air, similar to the vertebrae of some birds. Such air-filled bones would be lighter, making it easier for the Mamenchisaurus to hold up its giant neck, per the statement.

“Having such a long neck is a large weight that you have to position away from your body,” Cary Woodruff, a paleontologist at the Frost Science Museum who studies sauropods and did not contribute to the paper, tells the New York Times. “If you have to hold a hammer with your arm stretched out, your arm’s going to get tired pretty quick.”

For added support, the dinosaur had 13-foot-long ribs that would have made its neck more stable and less prone to injury, according to the statement. It also held its neck at a relatively shallow angle of 20 to 30 degrees.

“The long-necked dinosaurs evolved their own, different ways of coping with giantism and supporting long necks, and there are numerous amazing deposits with long-necked sauropods across China,” Natalia Jagielska, a paleontologist at the University of Edinburgh in Scotland who didn’t contribute to the research, tells New Scientist.

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