World's smallest fossilized sauropod footprint found in Xizang

BEIJING, Jan. 11 (Xinhua) -- Chinese scientists on Friday announced their discovery of two dinosaur track sites in southwest China's Xizang Autonomous Region, including one containing the world's smallest fossilized sauropod footprint, which dates back over 166 million years.

The track sites are located in a village in Qamdo City. In July 2023, a team of geologists discovered a series of reptile-like tracks on both sides of a village road. They collaborated with paleontologists on in-depth analysis and identified tracks left by sauropod and theropod dinosaurs from the Middle Jurassic period.

Their findings were published online in the Historical Biology journal in late December.

According to the study, one site contains a trail of three consecutive large theropod tracks, each approximately 42 centimeters in length. These tracks can be classified as belonging to the Eubrontes and are not common in Xizang's Jurassic dinosaur track records. The presence of these tracks indicates that medium-sized carnivorous dinosaurs, which could have reached lengths of up to 6 meters, once roamed the region.

The second site consists mainly of small, isolated sauropod tracks ranging from 8.8 to 15.5 centimeters, which were likely left by more than six dinosaurs with body lengths of up to 2 meters.

"Such tiny sauropod tracks are quite rare," said lead author Xing Lida, an associate professor at the China University of Geosciences Beijing. He noted that in previous research, sauropod tracks measuring 12.2 centimeters were recorded in the Republic of Korea, and tracks ranging from 11.5 to 13 centimeters were found in north China's Inner Mongolia.

"This discovery in Xizang has expanded our understanding of sauropod track sizes in the Qamdo area," Xing said. "It suggests that there may have been smaller sauropods in this region, or that these magnificent creatures practiced age separation and were well-developed at birth."

There was a remarkable size difference between adult and young sauropods. While fully grown sauropods could reach lengths of 20 to 30 meters, hatchlings would have been less than half a meter long when they first emerged from their eggs. Such a difference led to distinct movement patterns and food sources for different age groups, resulting in many sauropod species forming separate communities based on age, Xing explained.

Although the region is remote and situated at a high altitude, scientists have visited the area regularly since the 1970s. They have documented a significant number of Early Jurassic and Middle Jurassic dinosaur fossils. In 2011, Xing's team found Jurassic sauropod tracks near the No. 214 state highway in Qamdo.

Scientists say that in regions such as Qamdo, marine sedimentation gradually diminished during the Early Jurassic period, eventually transforming into an inland basin by the Middle Jurassic period. The deepest Jurassic stratum exceeds 4,800 meters, facilitating numerous fossil discoveries.

These discoveries highlight the vast potential of dinosaur research in Xizang, Xing said, adding that further dinosaur studies will continue making contributions to scientific research and public education in the region. ■