EDITOR'S DESK
A Giant Mystery
  



 

The Dinosaur Code

Major findings by Chinese paleontologists shed light on what is known
and not yet known about the lost giants

By TANG YUANKAI

TREASURE LAND: Deserts in China’s northwest are known worldwide as a potential goldmine for dinosaur fossil hunters

A live television broadcast of the excavation of dinosaur fossils in northwest China’s desert areas brought the attention of the nation to some of the country’s most underdeveloped places late this summer.

It was the first time a dinosaur fossil excavation had been filmed live in China, and on August 26 it happened at two sites, Lingwu in Ningxia Hui Autonomous Region and Changji in Xinjiang Uygur Autonomous Region, each place the site of a major discovery.

Despite the China Central Television (CCTV) presenter’s sensationalized reporting of the discoveries to millions of TV viewers, paleontologists on the front lines are remaining cool-headed about the scientific significance of the finds. Instead, they are viewing the discoveries as missing pieces in a jigsaw puzzle that may one day form a picture of the time when dinosaurs walked the earth.

Scientists focused on three major findings. First, fossils of the diplodocus, a huge herbivorous dinosaur, were for the first time unearthed in Asia. Second, the longest dinosaur neck fossil was discovered. Third, well-preserved fossilized teeth of a subgroup of the saurischian dinosaur, or “lizard-hipped” dinosaur, were unearthed.

Xu Xing, a renowned dinosaur expert and researcher with the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, noted that the discoveries are significant in the sense that dinosaur fossils of 160 million years ago are very rare, and the Jurassic period, beginning approximately 210 million years ago and lasting for 70 million years, is a key period of dinosaur studies. “The fossils found in Xinjiang and Ningxia will greatly promote the research of the evolution of dinosaurs,” Xu said.

Xu said the dinosaurs unearthed in Xinjiang lived in the Jurassic period and dinosaurs unearthed in Ningxia lived in the mid or late Jurassic or the Cretaceous period, but the exact dating requires further studies. He added that 10 dinosaur skeletons unearthed in Ningxia over the last two years were those of sauropods, while three dinosaur species have been unearthed in one pit in Xinjiang this time, including two herbivorous dinosaurs and one carnivorous dinosaur.

After the fossils were unearthed, technicians wrapped them with layers of asbestos paper before putting them in cloth bags. Then they sprayed plaster on the cloth bags and packaged them before sending the fossils to Beijing for restoration. Such complicated procedures are to avoid damage to fossils during transportation. Researchers hope the restoration work will to be finished by next September.

Diplodocus’ Asian debut

ASIAN RECORD: The herbivorous dinosaur unearthed in Xinjiang Uygur Autonomous Region is the longest ever found in Asia, measuring 35 meters in length

The Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences confirmed on TV on August 26 that the dinosaur fossils found in the city of Lingwu include the skull of a diplodocus, the first ever to be unearthed in Asia.

The small-headed diplodocus was the largest dinosaur ever discovered and among the longest land animals that was ever known to live. It measures about 27 meters long with an 8-meter-long neck and a 14-meter tail. Living in the late Jurassic and early Cretaceous periods approximately 150 million years ago, diplodocus was a huge plant-eater that traveled over 1,000 kilometers to search for food. Its fossils, mainly found in the American continent and Tanzania, had never before been found in Asia. Those unearthed in Lingwu belong to a subgroup of diplodocus.

For paleontologists, the most valuable dinosaur fossil is the skull fossil. Xu confirmed that the dinosaur skull found in Lingwu is among the best-preserved skulls of a sauropod dinosaur in the world. The body structure deduced from the unearthed bones suggests a close affinity between China’s diplodocus and dinosaur subspecies found in the southern hemisphere.

Tang Zhilu, a researcher with the Institute of Vertebrate Paleontology and Paleoanthropology, said fossils of 22 dinosaur teeth were unearthed, marking the first time in China’s dinosaur discovery history that stick-shaped teeth were found in the skull of a sauropod dinosaur.

Ningxia Hui Autonomous Region is the location of another site of dinosaur fossils, found in 2004 by a peasant living in the Nanciwan area. As of August 26 of this year, fossils of eight dinosaurs have been excavated at the site, making it among the few oases of sauropod dinosaurs that roamed through China about 160 million years ago. The site, which covers a large area, boasts even bigger excavation potential.

Dr. Mo Jinyou, who used to study under Xu Xing, said the fossils found in Lingwu are of a unique character. The fan-shaped spines on the back of the diplodocuses are much higher than in previously discovered fossils of this species. “This could shed light on the studies of diplodocus behavior and the surrounding natural environment,” Mo said.

Mo said that rock strata at the fossil site of Nanciwan suggest that dinosaur fossils there formed over a long period of time after dinosaurs drowned in a huge freshwater lake. The fact that the area hasn’t gone through major geographical alterations after the dinosaurs were buried is good news for researchers of the area’s natural environment of more than 100 million years ago.

Xu noted that the fossil findings in Lingwu are very significant for people studying the body structure, classification and evolution of sauropod dinosaurs as well as trying to understand the Mesozoic geography and global geographical distribution of ancient animals.

Scientists believe that the diplodocus appeared in areas around Lingwu in the late Jurassic period, which was the heyday of sauropod dinosaurs around the globe. During this period, dinosaurs ruled the globe as the largest animal, whose diversity and intelligence surpassed any other species on earth. At that time, the world climate was warm. The northern part of China was warm and humid throughout the Jurassic period, suitable for the diplodocus and possibly explaining why diplodocus fossils were found in Lingwu.

The era of the diplodocus overlapped with the period of the plate tectonics. “According to the well known ‘continental drift theory,’ the earth’s crust slowly drifted atop a liquid core to form the current continental structure at the end of the Triassic and during the early Jurassic period,” said Xu Xing. “But how the crust started to drift is still beyond people’s comprehension.”

Xu said that the discovery of diplodocus fossils in Lingwu might overthrow the popular presumption that the Asian plate was the first to drift away from the crust.

Mo Jinyou said that the discovery of diplodocus fossils in China, while supporting the continental drift theory as a whole, proved the drifting away of Asia could not be as early as some experts believe.

Meanwhile, Xu concludes that the gathering of information about the origin, distribution and migration of diplodocus in China still requires further analysis of the fossils unearthed in China and on other continents and geographical information about the latest excavation site. The result decides to what extent the theory of Asia as the first continent to drift away should be challenged, if at all, and the real reason behind today’s continental structure.

Longest dinosaur neck

MAJOR DISCOVERY: Paleontologists in Ningxia Hui Autonomous Region, in northwest China, study a recently uncovered diplodocus fossil, the first to be found in Asia

“This is the longest dinosaur neck ever unearthed in the world,” said senior engineer Wang Haijun of the Institute of Vertebrate Paleontology and Paleoanthro-pology at the excavation site of Changji in Xinjiang.

What lay in front of him was an L-shaped cervical vertebra fossil of a sauropod dinosaur. “The data of fossils of this dinosaur was transmitted to Beijing, where experts calculated the length of its neck as 15 meters,” he said. A dinosaur unearthed in Ohio in the United States set the previous world record of 12 meters. The projected total length of the Changji dinosaur is 35 meters.

The excavation site of Qitai, located at the eastern end of Junggar Pendi Basin, used to be a paradise for dinosaurs. Experts say the area used to be a lake with a humid climate and thick foliage, an estimated 180 million to 70 million years ago. Algae, ferns and mollusks grew on the banks of the lake, which was surrounded by swamps, offering an ideal living environment for dinosaurs.

When later a cataclysmic event triggered the extinction of the dinosaurs, the forests and lakes vanished and animals were buried deep in the earth. Since the 1920s, a handful of dinosaurs have been unearthed here in a 2-square-km area, including the world’s second largest dinosaur fossil. Scientists see this area as a dinosaur-rich region that in ancient times boasted a large variety of species. Fossils of at least 200 dinosaurs are said to be still buried in the area, and possibly among them undiscovered dinosaur species.

Although the recent excavation produced the record-breaking largest dinosaur in Asia, experts lament the failure to find a fossilized sauropod dinosaur skull. They had hoped to create a dinosaur discovery sensation by finding the skull of such a huge dinosaur.

Prior to the recent expedition, four complete dinosaur skulls had been unearthed in Xinjiang, all of which were of carnivorous dinosaurs. One reason for the difficulty in finding a skull of a sauropod dinosaur is that the skulls of herbivorous dinosaurs are much more fragile than those of carnivorous dinosaurs.

According to Wang, there are two reasons for the failure to find a complete skull. One is that the skulls were flushed away by water, he said. The other possibility is that the skull fossil is buried deeper than the cervical vertebra fossil, meaning that one could be unearthed in the next stage of excavation.

Why no eggs?

During the excavation in Qitai, experts have tried to dig up dinosaur eggs, but so far to no avail. No dinosaur egg has been unearthed in Xinjiang.

Different from other egg-laying creatures, some kinds of dinosaurs laid eggs and left them to hatch unattended. Scientists at the Institute of Vertebrate Paleontology and Paleoanthropology say there are three possible reasons for this lack of eggs found in the Xinjiang region. First, perhaps all the dinosaur eggs hatched, leaving none to fossilize. Second, the climate in the region wasn’t suitable for the hatching of dinosaur eggs and so the dinosaurs laid eggs in other areas. Third, while all the fossils in this area are from the Jurassic period, the found fossilized dinosaur eggs belong to the Cretaceous period, when frequent geographical movements made it difficult for these eggs to hatch.

One minority opinion at the Institute of Vertebrate Paleontology and Paleoanthro-pology is that a small animal living at the end of the dinosaur age lived by eating dinosaur eggs. Perhaps this animal, which reproduced at a high rate, ate up all the dinosaur eggs, leading to the extinction of dinosaurs in Qitai.