Tyrannosaurs
China's Junggar Basin

Photograph by Ira Brock National Geographic July 2008

Northwestern China's Junggar Basin is a sparsely settled region of arid badlands, dry washes, and desert dunes in the far western reaches of the Gobi. Some 160 million years ago, during the Jurassic period, the scene was much different: Imagine a vast marshy wetland populated by dinosaurs, tiny crocodilians, amphibians, and other creatures. Elsewhere in the world, dinosaurs are beginning to reach enormous sizes and to dominate the terrestrial ecosystems. But here in the Junggar Basin, the primitive ancestors of Tyrannosaurus rex and other reptile giants are still relatively small. Some are about to be frozen in time, as they step into quick mud and become entrapped, one on top of another. Eventually the mud will harden, capturing a dinosaurian story in stone.

This is one of the few places on Earth where the exposed terrestrial rock dates to the Middle Jurassic, a period critical to the origin and early evolution of major dinosaurian lineages, including birds. Composed mainly of mudstone, siltstone, and sandstone, the Shishugou (stone tree valley) formation gets its name from the beautiful petrified logs found here. These rugged badlands are also famed as the location of desert sequences in the 2000 movie Crouching Tiger, Hidden Dragon.

In 1928 an expedition to the Junggar Basin that included Yang Zhongjian, known as the father of Chinese vertebrate paleontology, discovered fossils of the medium-size sauropod (plant-eating dinosaur) Tienshanosaurus chitaiensis; a series of expeditions from the 1960s through the late 1990s yielded many other new species, including the gigantic long-necked sauropod Mamenchisaurus and the large carnivore Sinraptor. A scouting trip by paleontologists James M. Clark (of George Washington University) and Xu Xing (of Beijing’s Institute of Vertebrate Paleontology and Paleoanthropology) led to annual expeditions that have produced a startling collection of fossils—some 600 specimens so far—including Guanlong wucaii, the earliest known tyrannosaur.

Bibliography
Gwin, Peter. "The Real Jurassic Park." National Geographic (July 2008), 104-15.

"Dinosaurs From Xinjiang, China"

Other Resources
"Junggar Basin." Encyclopedia Britannica Online.

"Junggar Basin Semi-desert." World Wildlife Fund.

"The Middle Dinosaurs Kingdom."

"Charming Xinjiang Writes Epic of Tourism Takeoff." People's Daily Online, September 18, 2005.

Illustration
Map of outcrops featured in Crouching Tiger, Hidden Dragon. EarthSat GeoCover.

Other National Geographic Resources
Dino Death Trap. National Geographic Channel, 2007.

Prehistoric Time Line.

Allen, Thomas B. "Xinjiang," National Geographic (March 1996), 2-43.

They Started Small

Some of the new dinosaurs found in the Junggar Basin are primitive ancestors of giants that ruled in the Cretaceous period (145.5 million to 65.5 million years ago). But they started relatively small. Guanlong wucaii (crowned dragon of the five-colored rocks), the earliest known member of the tyrannosaur line that led to such iconic giants as Tyrannosaurus rex, was less than ten feet (three meters) long from its snout to the tip of its tail and probably weighed about 170 pounds (77 kilograms). In contrast, T. rex—which came on the scene more than 90 million years later—was about four times longer and perhaps 70 times heavier.

Another new species, Yinlong downsi, is the earliest known ceratopsian—a member of the dinosaur group that later included such well-known horned giants as Triceratops. Triceratops could reach 30 feet in length; Yinlong was about four feet long. The genus name Yinlong means “hidden dragon” in Chinese, a nod to the award-wining movie.

Bibliography
Xu Xing and others. "A Basal Tyrannosauroid Dinosaur From the Late Jurassic of China." Nature (February 9, 2006), 715-18.

Holtz, Thomas R., Jr. "A Jurassic Tyrant Is Crowned." Nature (February 9, 2006), 665-66.

Xu Xing, and others. "A Basal Ceratopsian With Transitional Features From the Late Jurassic of Northwestern China." Proceedings of the Royal Society B (September 7, 2006), 2135-40. Published online May 16, 2006.

Other Resources
"GW Biology Professor Leads Discovery of the Oldest-Known Ceratopsian, an Early Ancestor of Triceratops." GW News Center.

"Chinese Dinosaurs." Australian Museum.

Holtz, Thomas R., Jr., and Luis V. Rey. Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages. Random House Books for Young Readers, 2007.

Video
"Chinese Dinosaurs." Natural History Museum (London).

Other National Geographic Resources
Dino Death Trap. National Geographic Channel, 2007.

Owen, James. "T. rex's Oldest Ancestor Discovered in China." National Geographic News. February 8, 2006.

Barrett, Paul. National Geographic Dinosaurs. National Geographic Society, 2001.

Meet Junggarsuchus

Not all the diminutive species found recently in the Junggar Basin are dinosaurs. For example, Junggarsuchus sloani—named for the region where the fossil was found and for National Geographic's Chris Sloan, an amateur paleontologist who discovered the fossil in 2001—is a small (three-foot-long) crocodilian ancestor. Junggarsuchus's skull, with its crushing jaws, is similar to those of modern crocodilians—an order of reptiles that includes crocodiles, alligators, caimans, gavials, and related extinct forms—but its body had a more erect stance, indicating that it was better adapted to walking on land than are today's semiaquatic crocodilians. "The forelimbs were held underneath the body, not out to the side as in living crocodilians," says James Clark, lead author of the scientific paper on Junggarsuchus. No one knows why modern crocodilians adapted to a semiaquatic lifestyle, but studying species such as Junggarsuchus may provide new insights into crocodilian evolution.

Bibliography
Clark, James M., and others. "A Middle Jurassic 'Sphenosuchian' From China and the Origin of the Crocodylian Skull." Nature (August 26, 2004), 1021-24.

Roach, John. "In Crocodile Evolution, the Bite Came Before the Body." National Geographic News, August 25, 2004.

Matthew Lindsay. "Every Fossil Tells a Story: Professor James Clark Discovers Croc Ancestors in the Crossroads of Asia." By George! (December 2004.)

Other Resources
Clark, James M. "Crocodylia." In Encyclopedia of Dinosaurs, eds. Philip J. Currie and Kevin Padian. Academic Press, 1997.

Crocodilian Biology Database, Florida Museum of Natural History.

Last updated: May 28, 2008