BEIJING, July 24 (Xinhua) -- Researchers have made new discoveries about the origin of Sumatran striped rabbits from a 6.2 million-year-old fossil, according to the Chinese Academy of Sciences (CAS).

Sumatran striped rabbits generally have a gray body with brown stripes and live now in the mountainous regions of Sumatra and Southeast Asia. They have been classified as a critically endangered species due to their habitat, tropical rainforests, being seriously damaged.

The origin of Sumatran striped rabbits had been unclear for a long time until Chinese researchers found a group of rabbit fossil from the Late Miocene (11.6 million to 5.3 million years ago) in southwest China's Yunnan Province in 1986. The rabbits were considered the ancestor of Sumatran striped rabbits, said Deng Tao, a researcher from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the CAS.

Deng's team discovered a rabbit mandible fossil in Zhaotong city of Yunnan Province in 2015.

Over four years of cooperation with the Yunnan Archeology and foreign institutes, the researchers proposed that the rabbit fossil was the same species as the striped rabbits unearthed in 1986, as both inhabited wet marshlands.

The discovery is expected to clarify the origin of the Sumatran striped rabbits as well as reconstructing the species' evolution history.

This type of rabbit appeared throughout Southeast Asia and moved to the present Sumatra regions, said Deng.