A fossil with a trial of five footprints from a small-sized dinosaur was discovered in the Linxia Global GeoPark in northwest China's Gansu Province, shedding lights on scientific research on how dinosaurs shrank in size and evolved to birds.
With the length of 1 to 3 centimeters, it is one of the smallest dinosaur footprint fossils in the world. The footprints on the fossil belong to the small-sized dinosaur from the early Cretaceous period dating back to nearly 120 million years ago, said experts based on field observations.
"This is the first time for the footprints of small-sized dinosaurs to be discovered in Gansu Province and the rest of northwest China. These footprints will play important roles in strata comparison, dinosaurs scientific research and relative education. With these footprints, we can learn how dinosaurs' body size gradually decreased and how they evolved to birds, which bears huge significance in the evolutionary history of dinosaurs," said Xing Lida, an associate professor at China University of Geosciences (Beijing).
Fossils with small-sized dinosaurs' footprints were initially discovered in Sichuan Basin, followed by Shandong Province in eastern China and the Republic of Korea. Yet the new discovery in Gansu Province suggests the broader presence of small-sized dinosaurs' footprints in the early Cretaceous period, giving more insights into the biostratigraphy, geologic age and dinosaur diversity study in the region, according to Xing.
"The trail of footprints on the fossil indicates the speed of small-sized dinosaur is not very fast. The obvious water-shaped cracks on the fossil layer suggests the dinosaur once came close to water and there were many waterfowl alongside them. They formed a typical pack, and this aligns with what we found in other regions," said Xing.
A fossil assemblage of more than 2,000 fossils with dinosaurs' footprints have been discovered in Yongjing County of Linxia Hui Autonomous Prefecture since the end of 1990s. These differentiated and well-reserved fossils were discovered at multiple rock layers.
Fossil with small-sized dinosaur footprints discovered in China's Gansu
Members of the Shenzhou-19 crew aboard China's Tiangong Space Station successfully completed their second series of extravehicular activities (EVAs) at 01:12 (Beijing Time) on Tuesday, after performing multiple tasks including the installation of space debris protection devices and an extravehicular inspection.
Astronauts Cai Xuzhe, Song Lingdong and Wang Haoze worked for over eight hours to complete the tasks, with Cai and Song undertaking spacewalk duties. They were assisted by the space station's robotic arm and a team on Earth.
Song stepped out of Tiangong's Wentian lab module at 16:55 on Monday. Cai exited the module about two hours later to join Song on device installation tasks. Meanwhile, Wang stayed in the station's core module to provide support.
"The primary task is to install debris protection devices outside the module to safeguard its external cables from debris impact. Given the increasingly severe risk of space debris collisions in the orbital environment, we have carefully selected appropriate materials and made specialized designs. Additionally, the protection devices are designed to be easily and securely installed on the exterior of the space station, ensuring effective protection," said Li Zhihai, an aerospace engineer with the China Aerospace Science and Technology Corporation.
During their previous extravehicular mission in December, the Shenzhou-19 crew primarily installed protective devices for the external pipelines and cables of the Tianhe core module. Their second spacewalk put a focus on strengthening the Wentian lab module.
"Since the operational area for this mission differs from the previous one, the entire path planning process for the robotic arm must take into account the specific conditions around the Wentian module. It is essential to avoid any interference or collisions with the module itself or its solar panels. This requires maintaining a safe distance, which necessitates optimization in the design phase on the ground, along with extensive testing and validation," Li said.
The crew has completed all tasks smoothly and the two astronauts conducting the EVAs have returned to the Wentian lab module safely.
"The astronauts showed exceptional efficiency and speed throughout the entire process, and all installations were done perfectly," Li said.
The Shenzhou-19 crew have completed nearly half of their space journey and are scheduled to carry out a significant number of in-orbit scientific experiments and technological tests, according to the China Manned Space Agency.
Shenzhou-19 crew strengthens Tiangong station's debris protection in second spacewalk