Researchers explore the Shuanghe Cave. [Photo provided to chinadaily.com.cn]

An additional 2.6 kilometers have been added to Asia's longest cave, located in Suiyang county, Guizhou province, since last year, bringing its surveyed length to 439.7 kilometers, according to the results of the cave's 24th international scientific expedition released this month.

Researchers explore the Shuanghe Cave. [Photo provided to chinadaily.com.cn]

The Shuanghe Cave expedition, which began on Oct 11, further clarified the structure of the karst system and shed light on the cave's formation processes. Speleologists from China, France, Italy, Portugal, and Belgium also uncovered new paleontological material and traces of human activity.

Researchers identify evidence of animal bones burned by humans dated to roughly 1,400 years ago. [Photo provided to chinadaily.com.cn]

Among the finds were six giant panda specimens and fossil remains attributed to animals, including rhinoceroses and an ancient relative of elephants called a Stegodon. Investigators also reported four relatively complete specimens of the lingniu, a type of hoofed mammal, the first such discovery in China.

Stegodon fossils found in Shuanghe Cave. [Photo provided to chinadaily.com.cn]

Researchers identified evidence of animal bones burned by humans dated to roughly 1,400 years ago. "We speculate the cave may have been used as a trap for game," said Wang Deyuan, an associate research fellow at the Guizhou Academy of Sciences' Institute of Mountain Resources. "Hunters may have driven animals into the cave with torches, where they fell to their deaths and were subsequently roasted and eaten inside."

Panda fossils found in Shuanghe Cave. [Photo provided to chinadaily.com.cn]

To date, the Shuanghe Cave system has 115 confirmed entrances and remains the world's third-longest cave and the longest in Asia.

Local officials said the site has been added to the tentative list for World Heritage consideration and that materials to apply for Global Geopark status will be submitted shortly to higher forestry authorities for review.