The Earth has gone through multiple periods of warming and cooling over the past 2.5 million years; this has had a profound effect on the ice sheets and migration of different types of animals.
When the climate is cooler ice sheets tend to cover the Northern hemisphere, but when it warms these ice sheets are dramatically pulled back, a National Science Foundation news release reported. This influences animal migration in these regions.
New research suggests a five-million-year-old Tibetan fox called Vulpes qiuzhuding is most likely the ancestor of today's Arctic fox Vulpes lagopus.
The findings suggest the Arctic fox can be traced back to ancestors that adapted to the frigid conditions of high-altitude regions of Tibet.
Researchers found the remains of the ancient fox in Tibet, alongside ancient species such as: the"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," the news release reported.
These new fossil findings support the "Out of Tibet" hypothesis.
"The concept 'Out of Tibet' is an exciting insight for the origin of cold-adapted mammals of the Pleistocene," Rich Lane, program director in the National Science Foundation's (NSF) Division of Earth Sciences, which funded the research said in the news release. "It parallels the 'Out of Africa' theory for the evolution of hominids. Together they may be a model for wider application in biological history and geography."
The fossil sites are treacherous for researchers. The air is extremely cold and thin and the terrain is difficult to drive one. The researchers often must walk alone in search of fossils; especially in the lake margins which commonly hold megafauna.
"It's a pristine environment, the Tibetan people are kind, and in paleontological terms," Lane said, "it's relatively unexplored."
