The exciting discovery of an extinct species of Tibetan fox adds more credence to the out-of-Tibet hypothesis, in which the Tibetan Plateau served as a cradle of Ice Age megafauna in northern Eurasia.
For the last 2.5 million years, Earth has experienced cold and warm, millennia-long cycles that collectively have become known as the Ice Age.
During cold periods, continental-scale ice sheets blanketed large tracts of the northern hemisphere. As the climate warmed up, these colossal glaciers receded.
The advance and retreat of the ice sheets also had a profound influence in the evolution and geographic distribution of many animals, including those that live today in the Arctic regions.
Previously, paleontologists described a great number of extinct, cold-adapted species – of a wooly rhino (Coelodonta thibetana), three-toed horse (Hipparion), Tibetan bharal (Pseudois, known as blue sheep), chiru (Pantholops, known as Tibetan antelope), snow leopard (Uncia), badger (Meles), and 23 other mammals – that lived in what is now the Tibetan Plateau during the Pliocene and Pleistocene (5 million to 11,500 years ago).
This year, they discovered another Tibetan mammal – a 5 to 3-million-year-old fox, Vulpes qiuzhudingi, which was the likely ancestor of the living Arctic fox (Vulpes lagopus).
The origin of the Arctic fox and other cold-adapted mammals has usually been sought either in the Arctic tundra or in the cool steppes elsewhere. But the discovery of Vulpes qiuzhudingi boosts an alternative scenario, which scientists call the out-of-Tibet hypothesis.
It argues that some of the Ice Age megafauna used ancient Tibet as a ‘training ground’ for developing adaptations that allowed them to cope with the severe climatic conditions.
“There are a lot of challenges, but in paleontological terms, it is a relatively unexplored environment. Our efforts are rewriting a significant chapter of our planet’s recent geological history,” said Dr Xiaoming Wang from the Natural History Museum of Los Angeles County, who is the first author of a paper published in the Proceedings of the Royal Society B: Biological Sciences.
Xiaoming Wang et al. 2014. From ‘third pole’ to north pole: a Himalayan origin for the arctic fox. Proc. R. Soc. B, vol. 281, no. 1787; doi: 10.1098/rspb.2014.0893