Hadrosaur fossil: It is the most complete of all those unearthed in Inner Mongolia in 20 years.[Photo provided to China Daily]

A rare well-preserved hadrosaur fossil has been unearthed in the Inner Mongolia autonomous region and is expected to be of huge value for research into how the species evolved, Chinese archaeologists said.

More than 90 percent of the bones of the animal were intact, including the head, cervical vertebrae, limbs and a complete tail-bone. It is the most complete dinosaur fossil unearthed in Inner Mongolia in 20 years.

The fossil was first dis-covered in 2012 in Urad Back Banner, in the north-west part of the region. Excavation started in June 2013.

More than 300 fossil bone fragments were excavated at the site, weighing 1 metric ton altogether, said Tan Lin, an engineer at the Longhao Geological Institute of Paleontology in Inner Mongolia.