Chinese scientists have unveiled more information about the world's longest-necked dinosaur, Mamenchisaurus, dispelling the accepted view that the animal would have been able to raise its head like a giraffe.
Contrary to the fallacy that Mamenchisaurus could stride forward with its head held high, study on the neck bones of a well-preserved dinosaur revealed that it could raise its head only slightly higher than the body within an angle of 20 degrees.
Dr Ouyang Hui with the Chengdu University of Science and Engineering in Sichuan Province said that if the head and neck span was 6.5 meters, the most comfortable head position would be within 2 meters above its body.
For the first time, scientists used computerized tomography (CT) scanning technology to study the head of a well-preserved dinosaur fossil, Mamenchisaurus youngi, and unveiled new information on its skull cavity size, shape and construction -- all rare stuff for dinosaur neurology study.
The head contains 78 milliliters of brains, tiny compared to the huge body, but the brain had relatively advanced structural divisions.
Study of the sclerotic ring, a structure to adjust light into the eyes, indicated it had great eyesight.
When the dinosaur's teeth wore out, new ones grew at the same time in other cavities on the gum so that it could continue to chew food, the research thesis showed.
A researcher with the United States once proposed that the neck of Mamenchisaurus was level instead of vertical to the body, reasoning the dinosaur needed a much stronger heart to support such a pose, but most people still likened the long-necked animals to giraffes, said Xu Xing, a researcher with the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP).
"This is the first systematic research on Mamenchisaurus providing a lot of evidence and information," said He Xinlu, former vice-director of the China Society of Vertebrate Paleontology.
Mamenchisaurus was indigenous to east Asia and has been studied for half a century beginning in 1954.
It was once the most famous dinosaur in China before the discovery of a feathered dinosaur in 1996, the thesis says. Previous opinions on the phylogenetic position of Mamenchisaurus varied because of the lack of reliable skull information and a complete description.
Mamenchisaurus youngi was unearthed in Xinmin County in Zigong City in southwest China's Sichuan Province in 1989. The specimen, 16 meters long with a 6.5 meter neck, is relatively small among various species of Mamenchisaurus, compared to the biggest one ever found in China spanning 35 meters long.
Mamenchisaurus youngi, the best preserved specimen of Mamenchisaurus, helped scientists develop a detailed description of its complete skeleton framework, especially the skull, visual descriptions of the sclerotic ring, and the fossilized skin of sauropods, which are rarely discovered, He Xinlu said.
Mamenchisaurus fossils have been found exclusively in China in places like the Sichuan Province, Yunnan Province, Xinjiang Uygur Autonomous Region and Gansu Province.
The animals lived on foliage in the late Jurassic, about 150 million years ago.
(Xinhua News Agency July 4, 2003)
