A sauropod from the Late Jurassic epoch had the longest neck of any dinosaur on record – stretching 15.1 metres, based on analysis of its vertebrae.
Mamenchisaurus sinocanadorum was discovered in Xinjiang province in China in 1987, but only a few bones, including some of its vertebrae and a rib, were preserved. It was named officially in 1993, but the animal’s size and scale haven’t been fully established until now.
The original paper reporting the discovery of the sauropod didn’t provide a neck length, but implied it would be between 10 and 11 metres.
Rather than simply analysing what the bones of a dinosaur look like and what that indicates about its overall skeleton, palaeontologists also consider evolutionary links with similar, more complete, specimens.
“It’s shockingly simple and speaks to the fact that we’ve benefited from the discovery of additional species in the intervening time [since M. sinocanadorum was discovered],” says Andrew Moore at Stony Brook University in New York.
To come up with their estimate, Moore and his colleagues looked at the relative proportions of the remaining vertebrae from M. sinocanadorum and compared them with related dinosaurs for which we have fossils of the entire neck. At 15.1 metres, its neck would have been six times longer than a giraffe’s.
Another question Moore and his colleagues tried to tackle was how the sauropod could have supported the weight of such a long neck. By putting the remaining vertebrae in a computed tomography (CT) scanner, they realised that between 69 and 77 per cent of the vertebrae was empty space.
“Having such a long neck was made possible, we think, not only by making the bones lightweight by replacing marrow with air, but also potentially limiting the mobility of the neck so it’s more amenable to being pumped full of air,” says Moore. Cervical ribs that interlink below the neck also helped support the neck, the researchers believe.
“The long necks of these animals are amazing even by dinosaur standards and understanding their evolution is really important to see how these animals lived,” says David Hone at Queen Mary University of London.
“This study proves there is more to learn about and from dinosaurs,” says Natalia Jagielska at the University of Edinburgh, UK. She is particularly excited about the potential of future finds. “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,” she says.