Fossils of two giant rhinos dating back around 22 million years have been unearthed in China, according to a study released Thursday.
They are among the last relics of the gigantic animal, which was discovered with great fanfare at the beginning of the last century. Much larger than modern rhinos, giant rhinos often stood over 20 feet tall at the shoulder and weighed over 20 tons, making them larger than mammoths and the largest land mammal that ever lived.
The new fossils were discovered in May 2015 in the Linxia region of northwest China’s Gansu Province. One fossil consists of a skull, jaw and teeth, and the atlas vertebra – where the head connects to the spine – while the other consists of three vertebrae.
From these remains, scientists have reconstructed the ancient animals. And they discerned enough differences in their skeletons to classify them as a new species, according to research published in the journal Communications Biology. They nicknamed him Paraceratherium linxiaensis – the first name of its larger group of giant rhinos, and the second of the region where it was found.
Tao Deng, director of the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences in Beijing, explained that the Linxia area has been famous for its fossils since the 1950s, when local farmers discovered there for the first time “dragon bones” which were used to make traditional medicines.
Deng’s team has searched for fossils in Linxia since the 1980s and found several complete skeletons of ancient mammals, he said in an email. But they had only found fragments of giant rhino fossils before, although more complete fossils have been found elsewhere in China.
The new species of giant rhino isn’t quite the biggest – Deng said it’s slightly smaller than Dzungariotherium orgosense, a species identified from fossils from China in the 1970s, but it was about a fifth larger than the relatively common Paraceratherium bugtiens, the first remains of which were identified in what is now Pakistan in the early 1900s.
None of the giant rhinos had horns on their noses, however, despite being the ancestors of modern rhinos: the horns they are named after are a much later adaptation.
Giant rhinos became world famous in the 1920s after an expedition to Mongolia and China by famous American explorer Roy Chapman Andrews, the role model for several early Hollywood heroes.
Andrews’ team found giant rhino fossils in the largely unexplored Gobi Desert and returned a fossilized skull of a beast to New York City, where it was on display at the American Museum of Natural History. The discovery was such a success that the giant rhinos briefly eclipsed even the largest dinosaurs in the public imagination, according to historian Chris Manias of King’s College London.
Donald Prothero, a paleontologist at the Natural History Museum of Los Angeles County and author of a book on giant rhinos, said the huge animal was one of the last surviving giants to stalk the earth.
Although gigantic mammals were common in some earlier periods of prehistoric times, most became extinct when the climate became much drier during the Oligocene period, around 34 to 23 million years ago, has he declares.
This led to the disappearance of the vast forests of the Earth, and most of the mammals that depended on them for food have disappeared. But the giant rhinos still survived for a while.
“It was a much drier climate with a lot of open grass, and trees were about the only resource that large mammals could live on,” he said. “So they would go from one stand of trees to another.”
Deng notes that the new species of giant rhino was closely related to the Pakistani species, raising the possibility that a close ancestor species once roamed the Tibet region before becoming the raised plateau it is today.