Fossilised skull suggests cheetahs evolved in Asia not Americas

The most primitive cheetah ever found throws into doubt the theory that the fleet-footed feline shared a common ancestor with pumas

James Randerson, science correspondent guardian.co.uk
Monday 29 December 2008 22.00 GMT

The fossilised skull of a big cat unearthed in north-west China has been identified as the most primitive cheetah ever found. The skull, which is between 2.16m and 2.55m years old, is superbly preserved and its location has cast doubt on ideas that cheetahs evolved in the Americas.

One theory is that modern cheetahs shared a common ancestor with pumas in the Americas, but the fossil record of the puma goes back only around 400,000 years in the US. Because the current find is so much older, it is strong evidence for an evolutionary origin for cheetahs in Asia.

Cheetahs are the fastest land animal, using short bursts of speed in excess of 70mph to capture prey. They are now found almost exclusively in Africa and are classified by the International Union for the Conservation of Nature's Red List of endangered species as vulnerable to extinction.

One sub-species called the Asiatic cheetah still exists in Iran. Numbering between 60 and 100 individuals and critically endangered, according to the Red List, it represents the remnants of a much larger population that was once widespread across Asia but was devastated by human-induced habitat destruction and hunting.

The new find, from the Linxia basin in China's Gansu province, suggests that Asia was the evolutionary cradle for the fleet felines. The nearly complete skull is among the oldest cheetah fossils yet found. It is around the same age as a 2.5m year-old related species discovered in Casablanca, Morocco, in 1997.

But according to its discoverers, Dr Per Christiansen at the Zoological Museum in Copenhagen, and Dr Ji Mazák of the Shanghai Science and Technology Museum in China, the new find – dubbed Acinonyx kurteni – has a unique set of characteristics. "We present a new discovery from the late Pliocene of China of a new species of primitive cheetah, whose skull shows a unique combination of primitive and derived characters," they wrote in the journal Proceedings of the National Academy of Sciences. The big cat's evolutionary history is poorly understood because few fossils have been found.

The skull is around the same size as living cheetahs, but it has a very wide braincase relative to the skull's length. It also has enlarged frontal sinuses and its teeth are "surprisingly primitive", according to the researchers.

They suggest that other cheetah specimens that are known only from fossilised teeth may have been misidentified by other scientists. "The dentition is far more primitive than in all other cheetah-like cats, raising doubts on the identification of isolated dental finds of large cats from the Pliocene-Pleistocene of Eurasia and Africa, which are often attributed to leopards," they wrote.

http://www.guardian.co.uk/science/2008/dec/29/fossil-cheetah-skull-evolution