Pandas

Fossils of giant pandas dating as far back as the middle Pleistocene era (about 600,000 years ago) have been found in central and southern China. This suggests that the prehistoric range of giant pandas was much greater than at present, which is restricted to portions of north-central Sichuan Province and southern Gansu Province, and the Qinling Mountains of Shaanxi Province of China.

Giant pandas are descended from the same ancestral carnivores as bears, raccoons, dogs, and cats, and so are placed in the order Carnivora (carnivores) within the class Mammalia (mammals). Pandas have, however, almost entirely lost the meat-eating habit. It is not yet fully resolved whether giant pandas are more closely related to the bear family (Ursidae) or the raccoon family (Procyonidae).

The first non-Chinese person to describe the giant panda was Pere Armand David, a French missionary living in China, in 1869. He called the panda a bear, based on its bear-like appearance. The next year scientists in Europe examined skeletons and concluded that giant pandas resembled red pandas (which were classified within the raccoon family) more than they did bears. This element of panda classification is still being examined by biologists.

Many aspects of the panda's skeletal structure and behavior support the idea that it is not a bear. An especially important piece of evidence is the presence of a special "sixth digit," which acts in the manner of an opposable thumb. This digit is actually an extension of a bone in the wrist, and it allows giant pandas to grasp bamboo shoots and efficiently strip off their leaves. The red panda also has such a "thumb," although it is less well-developed. Other aspects of panda biology which bears do not possess include: well-developed molar teeth and non-hibernation in winter.

Techniques in molecular biology have allowed scientists to create a "family tree" (or phylogenetic tree) of the relationships among bears, pandas, and raccoons. This has suggested that giant pandas are more closely related to bears than to raccoons, whereas red pandas are more closely related to raccoons.