Staff members install scaffold before dinosaur footprints preservation at a geological park in Yanqing of Beijing, capital of China, May 24, 2018. Experts from China and Greece have recently started their first joint preservation work on more than 170 fossilized dinosaur footprints discovered in a suburb of Beijing. (Xinhua/Li Ran)

BEIJING, May 25 (Xinhua) -- Experts from China and Greece have recently started their first joint preservation work on more than 170 fossilized dinosaur footprints discovered in a suburb of Beijing.

The team has started to clean the surface of the fossils and apply a special reagent to prevent them from weather damage.

The footprints, unearthed in a geological park in Yanqing County in 2011, are the first dinosaur traces to be found inside the city.

They are believed to be left by dinosaurs that lived some 140 to 150 million years ago in the late Jurassic Period.

The fossils are of interest in the study of China's dinosaurs during the late Jurassic and early Cretaceous periods.

"The footprints need regular ongoing preservation work," said Zeng Guangge, an administrator with the Yanqing Geopark.