Tibet Could Have Been the Polar Carnivore Motherland
Researchers have uncovered the fossils of a hyper-carnivorous fox that once roamed the frozen Tibetan Plateau. This and other fossil evidence helps support the theory that the great majority of polar carnivores originated from ancient Tibet.
A study published in the journal Proceedings of the Royal Society B describes how jaw fossils from an ancestor of the modern-day arctic fox indicate a level of carnivorous tendencies that make most small predators look like vegans.
According to pale biologist and study co-author Zhijie Jack Tseng, a lack of cusps among the lower molars of the jaw fossils discovered indicate that the ancient fox was a "hypercarnivore" - a predator that exclusively eats meat. Many modern-day carnivores will occasionally supplement their diets with nuts or berries to obtain some hard-to get-nutrients. Many modern foxes are even omnivorous, equipped with sharp canines and dull molars so that they can eat equal parts plant and animal.
However, with such sharp chompers, it was clear that this ancient fox exclusively ate meat, slicing into its prey with extreme efficiency.
Tseng says that such a diet makes sense in polar conditions, where there is a high demand for protein and heavy fats on a daily basis.
This also reflects the "Out of Tibet" theory, which Tseng supports. According to the theory, nearly three million years ago the Tibetan Plateau served as a kind of "third pole," as it was colder than the Arctic at the time. Mammals living in Tibet adapted appropriately to these conditions, developing thick coats and become hypercarnivores long before climates changed.
When temperatures dropped at the start of the Ice Age, these mammals "migrated down from the plateau and spread northward toward the vast expanse of Russia, Siberia, and northern Canada, where they became characteristic Ice Age mega-mammals," Tseng told National Geographic.
This would also explain why the ancient Tibetan fox bears a "striking resemblance" to the modern arctic fox, according to the study.
Still, the authors admit that this is only a theory, and the fox fossils may simply be coincidence or an example of convergence - when two separate species develop remarkably similar adaptations.
The study was published in the Proceedings of the Royal Society B. on June 10.