Washington: A new study suggests that the advance and retreat of the ice sheets millions of years ago had a profound influence in the evolution and geographic distribution of many animals, including those that live today in the Arctic regions.
The study identifies a newly discovered 3 to 5-million-year-old Tibetan fox from the Himalayan Mountains, Vulpes qiuzhudingi, as the likely ancestor of the living Arctic fox (Vulpes lagopus), lending support to the idea that the evolution of present-day animals of the Arctic region is intimately connected to ancestors that first became adapted for life in cold regions in the high altitude environments of the Tibetan Plateau.
The paper`s lead author is Xiaoming Wang, of the Natural History Museum of Los Angeles County (NHM). Co-authors are Zhijie Jack Tseng (University of Southern California), Qiang Li (Chinese Academy of Sciences), Gary T. Takeuchi (Page Museum at the La Brea Tar Pits), and Guangpu Xie (Gansu Provincial Museum).
These writers, on a team with other geologists and paleontologists and led by Wang, uncovered the fossil specimens in the Zanda Basin in southern Tibet in 2010.
In addition to the arctic fox, the team also uncovered extinct species of a wooly rhino, three-toed horse, Tibetan bharal (also known as blue sheep), chiru (Tibetan antelope), snow leopard, badger, as well as 23 other mammals.
The origin of the cold-adapted Pleistocene megafauna has usually been sought either in the arctic tundra or in the cool steppes elsewhere.
But the team`s new fossil assemblage boosts an alternative scenario, which the authors call the "out of Tibet" hypothesis.
It argues that some of the Ice Age megafauna (which in North America include the woolly mammoth, saber-toothed cat, giant sloths, and others) used ancient Tibet as a "training ground" for developing adaptations that allowed them to cope with the severe climatic conditions. These Tibetan ancestors were thus pre-adapted to cold climates during the Ice Age (2.6-.01 million years ago).
The study is published in the Proceedings of the Royal Society B: Biological Sciences.