BEIJING, Sept. 17 (Xinhua) -- A new study by Chinese researchers has revealed how fast theropod dinosaurs could run during the Cretaceous period.

By analyzing fossilized tracks, they identified the fastest-known Cretaceous theropod, which could reach speeds of up to 45 kilometers per hour, according to a study published in Science China Earth Sciences.

The Otog Dinosaur Trace National Nature Reserve in north China's Inner Mongolia Autonomous Region is the only national nature reserve in China featuring dinosaur traces.

The researchers from the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences, in collaboration with Shenyang Normal University and the West Ordos National Nature Reserve Administration of Inner Mongolia, discovered a new theropod dinosaur tracksite. They identified large and medium-sized track morphotypes, forming four trackways and two isolated footprints at the nature reserve.

Among them, a medium-sized theropod trackway consists of five consecutive footprints, each averaging 25.25 centimeters in length, with a stride measuring up to 5.3 meters.

The study indicates that the trackmaker could reach speeds of around 45 kilometers per hour, making it the fastest-known theropod trackway documented from the Cretaceous period.

This discovery offers crucial fossil evidence for understanding the maximum running speeds of medium-sized theropod dinosaurs.

The other three trackways and two isolated footprints were left by large theropods, according to the research article. The individual footprints averaged 44.92 centimeters in length, with a stride of 2.5 meters, indicating a walking speed of six to eight kilometers per hour.

After recently removing the surface sediment blanketing the trackway's starting point, the researchers uncovered 69 footprints, extending the trackway to 81 meters, making it the longest theropod trackway recorded in China.

These newly discovered high-speed trackways occur alongside those of large theropods, leading researchers to suggest that the rapid locomotion may reflect either active hunting or an attempt to escape predation by larger contemporaries. ■