A dinosaur with a 15-metre-long neck could potentially be the longest neck ever seen in an animal, scientists believe.
Known as Mamenchisaurus sinocanadorum, the dinosaur roamed east Asia and other parts of the world more than 160 million years ago.
At 15.1 metres, its neck was more than six times longer than the necks of giraffes and 1.5 times the length of a double-decker bus, the scientists said.
Dr Andrew J Moore, a palaeontologist at Stony Brook University, New York, said: “With a 15-metre-long neck, it looks like Mamenchisaurus sinocanadorum might be a record-holder – at least until something longer is discovered.”
M. sinocanadorum belongs to a subgroup of dinosaurs known as sauropods.
Dippy, the famous life-size replica of a Diplodocus carnegii skeleton given to the Natural History Museum in London, belongs to this group.
The M. sinocanadorum fossils were first discovered in China in 1987 within 162-million-year-old rocks.
Dr Moore and his colleagues re-examined the specimens as part of their research documenting the diversity and evolutionary history of the dinosaurs.
The team was keen to find out how sauropods managed to evolve such long necks and large bodies without collapsing under their own weight.
Although M. sinocanadorum is known only from a handful of bones from the neck and skull, scientists were able to reconstruct its size and shape with help from complete skeletons of its closest relatives.
Analysis revealed M. sinocanadorum had a neck approximately 15.1 metres long, the longest of any known sauropod.
Dr Moore said: “All sauropods were big but jaw-droppingly long necks didn’t evolve just once.
“Mamenchisaurids are important because they pushed the limits on how long a neck can be and were the first lineage of sauropods to do so.”
The paleontologists used a technique known as computed-tomography (CT) scanning which revealed the vertebrae – back bones – of M. sinocanadorum were lightweight and hollow with air spaces taking up nearly three-quarters of the volume.
To compensate for its lightweight bones, M. sinocanadorum had rod-like ribs in the neck about four metres long to help with its stability, the team said.
The researchers then hypothesised on how these creatures would have breathed air into their lungs.
Professor Paul Barrett, merit researcher at the Natural History Museum London, said: “Like all other sauropod dinosaurs, Mamenchisaurus had a complex breathing apparatus that included not only the lungs, but also numerous balloon-like air sacs.
“These were connected to the lungs and windpipe but spread throughout the interior of the animal’s neck, chest and abdomen.
“Taken in combination, these air sacs had a much greater volume than the lungs and they even went inside the bones, hollowing them out.
“This extra space would have helped these gigantic sauropods to move the large volume of air in the lengthy windpipe that would have occupied their extraordinary necks.”
While M. sinocanadorum is now thought to have the longest neck, it is not the biggest dinosaur.
That title is held Patagotitan mayorum, one of the largest known creatures to have ever lived. It is thought to have been 37.5 metres long, weighing in at about 57 tonnes.
Dinosaur enthusiasts will be able to see the P. mayorum on display in the summer at the Natural History Museum, with tickets on sale now.
The research is published in the Journal of Systematic Palaeontology.