A new study published in the Proceedings of the Royal Society B: Biological Sciences by an international team of researchers, including Z. Jack Tseng, a Frick Postdoctoral Fellow in the Museum’s Division of Paleontology, identifies a newly discovered 3- to 5-million-year-old Tibetan fox from the Himalayan Mountains, Vulpes qiuzhudingi, as the oldest close relative of the living Arctic fox Vulpes lagopus.
The finding lends 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.
”These fascinating fossil discoveries continue to change our collective knowledge about how current-day distributions of animals may have been dramatically different from extinct ecological communities as recent as 3 million years ago, ” says Dr. Tseng. “They also demonstrate what research on both the geographic origin and subsequent dispersal of megafaunal species can reveal about biological response to climate change.”
For the last 2.5 million years, our planet 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, leaving Yosemite-like valleys and other majestic geologic features behind.
The advance and retreat of the ice sheets had a profound influence on the evolution and geographic distribution of many animals, including those that live today in the Arctic regions.
On an expedition led by Xiaoming Wang of the Natural History Museum of Los Angeles County, Tseng, along with researchers from the Chinese Academy of Sciences, the Page Museum at the La Brea Tar Pits, and the Gansu Provincial Museum, 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 woolly rhino, three-toed horse, Tibetan bharal (also known as blue sheep), chiru (Tibetan antelope), snow leopard, badger, and 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 already adapted to cold climates by the start of the Ice Age (2.6-.01 million years ago).