Giant rhino find offers clues to plateau's past

LANZHOU-Researchers confirmed recently that a previously unknown species of giant rhino lived in the region of today's Qinghai-Tibet Plateau some 26.5 million years ago, providing insight into the evolution of both the large land mammal and the plateau.

Deng Tao, a researcher at the Chinese Academy of Sciences' Institute of Vertebrate Paleontology and Paleoanthropology and leader of the project, said that the Sino-US research team declared Paraceratherium linxiaense-named for its discovery site in Gansu's Linxia Basin-a newly discovered giant rhino species from the Oligocene Epoch.

The team, which included members from the Institute and Harvard University, also drafted a more detailed family tree and a migration map for giant rhinos, based on their findings, he added. The results of the study have been published in the Nature Publishing Group journal Communications Biology.

"It's worth noting that the Qinghai-Tibet Plateau was likely host to areas with low elevations, possibly under 2,000 meters, during the Oligocene and the giant rhino lineage could have moved freely along the eastern coast of the Tethys Ocean, and perhaps through lowlands in the region," Deng said.

Chinese researchers discovered a 1.2-meter-long giant rhino skull with an articulated mandible and its topmost vertebra in sandstone beds in the Linxia Basin, on the northeastern side of the Qinghai-Tibet Plateau, in May 2015.

The discovery led to the Sino-US study, which confirmed the skull belonged a previously unknown species of giant rhino.

One of the largest land mammals to ever live, the giant rhino had a larger skull and longer legs than any others discovered.

"Its body size was suited to open woodlands in humid or arid climatic conditions," Deng said.

A giant rhino could weigh up to 24 metric tons-as much as four African elephants-and stand up to 5 meters tall at the shoulder.

Except for some remains found in Eastern Europe, Anatolia and the Caucasus, giant rhinos are believed to have lived mainly in Asia, particularly in modern-day China, Mongolia, Kazakhstan and Pakistan. All six genera of the giant rhino are known to have roamed from northwest to southwest China from the middle Eocene to the late Oligocene periods.

Among them, only Paraceratherium bugtiense, which was discovered in the southwestern corner of the Qinghai-Tibet Plateau, is well-recorded, making the genus the key to the origin and dispersal history of giant rhinos, Deng said.

The study also helped shed light on the evolution of the Qinghai-Tibet Plateau, which scholars believe began to rise about 65 million years ago.

"Our findings and the study suggest the widespread occurrence of open woodland during the late Oligocene in northwestern China," Deng said. "The study tells us that the appearance of the Qinghai-Tibet Plateau about 26.5 million years ago was very different to what it is today."