(CNN) A herbivorous sauropod that prowled around what is now China about 162 million years ago had a neck about 10 feet longer than a standard school bus—and the longest of any known dinosaur.
The creature’s 49.5-foot-long (15.1 meter) neck would have allowed it to stand in one place and suck up the surrounding vegetation—maximizing the amount of food it consumed while conserving energy.
The fossilized remains of the dinosaur, called Mamenchisaurus sinocanadorum, were discovered in 1987 in China’s northwestern Xinjiang region and first described in a 1993 scientific paper. The dinosaur was named after the joint Sino-Canadian team that unearthed the fossil.
In a new analysis of the fossil published in the Journal of Systematic Palaeontology on Wednesday, paleontologists used computerized topography scanning that was not widely available three decades ago to compare M. sinocanadorum with other related sauropods that have been unearthed In recent years.
“Mamenchisaurids are important because they pushed the limits of how long a neck can be, and were the first lineage of sauropods to do so. With a 15-meter neck, it looks like Mamenchisaurus sinocanadorum could be a record holder—at least until something longer is detected,” the study said lead author Andrew Moore, a paleontologist and assistant professor at New York’s Stony Brook University, said in a statement.
The paleontologists were able to infer the length of the neck by studying the specimen’s three preserved vertebrae and comparing them to the neck bones of closely related dinosaurs.
“We actually happen to know who it’s related to, which makes for good comparisons. In this case, it’s well nested evolutionarily within a lineage that we know had 18 cervical vertebrae,” Moore explained. “We can scale up from the comparators to work out absolute neck length.”
The longest complete neck documented by scientists belongs to a fossilized dinosaur called Xinjiangtitan, Moore said, and it was about 1.5 meters shorter than the neck of M. sinocanadorum.
Hollow legs ease the load
The study also revealed exciting details about these huge dinosaurs. Similar to a bird’s lightweight skeleton, M. sinocanadorum’s bones were filled with air, rather than marrow, which is a characteristic of most mammalian bones. Computed tomography showed that air made up 69% to 77% of the vertebral volume.
“Probably that’s an important mechanism for building such a long neck because it’s going to be quite heavy,” Moore said.
The longest full neck documented by scientists belongs to a fossilized dinosaur called Xinjiangtitan (top). M. sinocanadorum (bottom) has an even longer one, researchers believe.
While the posture of some sauropod species may have had a neck that was held upright in a swan-like fashion, Moore said biomechanical studies suggested the Mamenchisaurid neck was elevated at an angle of about 20 to 30 degrees above the horizontal.
But even at this relatively shallow angle, the neck’s extreme length would still mean that the animal’s head could reach heights of about 24.6 to 32.8 feet (7.5 meters to 10 meters) above the ground.
The sauropod’s evolutionary adaptations — gigantic size and vegetarian diet — have no modern equivalent, according to the study. But the lineage of these long-necked dinos was very successful, with various sauropod species appearing early in the dinosaur era and flourishing until they died out 66 million years ago.
“They are apparently well-engineered to be efficient foragers and that’s what the neck allows them to do … plant themselves in a space, eat the vegetation around them and then move only as needed.
“As for why Mamenchisaurus among sauropods had relatively even longer necks? Maybe it’s just that much more efficient… It’s hard to say but it’s clearly something central to their biology.”