Ailuropoda microta, rarely called the Dwarf Panda, Dwarf Giant Panda, or Pygmy Giant Panda, is the earliest known ancestor of the Giant Panda. It measured 1 m (3 ft.) in length; the modern Giant Panda grows to a size in excess of 1.5 m (5 ft.). Wear patterns on its teeth suggest it lived on a diet of bamboo, the primary food of the Giant Panda. The first discovered skull of the animal in a south China limestone cave is estimated to be 2 million years old. The skull found is about half the size of a modern day giant panda, but is anatomically very similar. This research suggests that the giant panda has evolved for more than three million years as a completely separate lineage from that of other bears.