September 2, 2011
Scientists Unearth Oldest Woolly Rhino In Tibet
A 3.6-million-year-old woolly rhinoceros fossil discovered in Tibet in 2007 indicates that some giant mammals may have evolved in the Tibetan highlands before the beginning of the Ice Age, according to experts.
In a paper published on September 2 in the magazine Science, paleontologists from the Natural History Museum (NHM) of Los Angeles County and the Chinese Academy of Sciences, who discovered the rhino´s complete skull and lower jaw, argue that the beast adapted to global cooling before it even happened.
The extinction of giants from the Ice Age such as woolly mammoths and giant sloths has been widely studied, but it has remained unclear about where these giant beasts came from, and how they acquired their adaptations for living in extreme cold environments.
The team, led by NHM´s Xiaoming Wang and CAS´s Qiang Li, said among the special adaptations was a flat horn useful for sweeping snow away to find vegetation. With special adaptations, the giant mammals were able to spread to northern Asia and Europe once the Ice Age started 2.6 million years ago.
The fossil is believed to be the oldest specimen of its kind yet to be found. It lived nearly 3.6 million years ago, long before similar animals that roamed northern Asia and Europe in the Ice Age.
“The Tibetan Plateau may have been another cradle of the Ice Age giants,” report the researchers.
The woolly rhino fossil was well preserved -- “just a little crushed, so not quite in the original shape; but the complete skull and lower jaw are preserved,” Xiaoming told BBC News.
The fossil was found in Tibet´s Zanda Basin. The area is rich in fossil beds, and the rhino was unearthed along with other fossils, including horse, antelope, snow leopard and many other kinds of mammals.
The team´s assemblage of fossils offers new insights into the origin of the cold-adapted Pleistocene mega-fauna. The harsh winters of the Tibetan Plateau may have provided the initial step towards cold-adaptation for many species of mammal in Europe, Asia, and even North America.
“This discovery clarifies the origin of the woolly rhinoceros – and perhaps much of the now extinct, cold-adapted, Pleistocene Eurasian mega-fauna – as the high-altitude environments of the Zanda Basin of the primordial Pliocene Himalayas,” said H. Richard Lane of the National Science Foundation´s Division of Earth Sciences.
Xiaoming said many more woolly rhino fossils will need to be found before experts can make a proven statement of how and where the rhinos adapted and evolved for the Ice Age. But the new discovery surely helps that case.
Andy Currant, an expert on the Pleistocene at London´s Natural History Museum, said the task of finding more woolly rhino fossils would be difficult at best. “Woolly rhino were preyed on by spotted hyenas and they were eaten pretty thoroughly; the hyenas liked the bones,” he told BBC News.
“Cold places, such as Tibet, Arctic, and Antarctic, are where the most unexpected discoveries will be made in the future,” said Xiaoming. “These are the remaining frontiers that are still largely unexplored.”
Scientists put the rhino in a new species classification -- Coelodonta thibetana.
Image Caption: Artist's reconstruction of Tibetan woolly rhino that "snow swept" for vegetation. Credit: Julie Naylor
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