Known as China's "Fossil City," Chaoyang of northeast China's Liaoning Province opened its largest promotional event at the Shanghai World Expo Monday, displaying fossils of what might be the world' s earliest birds and flowers.

Hua Ruiqi, the city's vice mayor, said at the opening ceremony of "Chaoyang Week" held at Liaoning Pavilion, that thousands of bird fossils had been unearthed in Chaoyang, which made the city well-known.

Archeologists have found many important paleontological discoveries in Chaoyang, and the surrounding Harqin region is believed to be the oldest known prehistoric site in northern China.

Two of the most remarkable Early Cretaceous birds known to date were recovered in the city and named "Longipteryx chaoyangensis" and "Sapeornis chaoyangensis," in reference to the city.

The city has become the focus of great interest in the palaeontology field. Archeologists say some of the findings have completely revolutionized the ideas of dinosaurs and shed new light on the origin of birds.

Vice Mayor Hua said the promotional activities seek to introduce Chaoyang to Expo visitors and explain the archeological value of the city.