Why does the Chinese Zodiac not include pandas?

Or red deer or crocodiles? Since the cycle is only 12 years long, not every animal could make the list.

Or the bat.

They wanted to add pandas, but they don’t get along with the other animals. It would have been pandamonium.

And why did they include the rat?

The Chinese zodiac is demonstrative of their long lived philosophy regarding balance; good and bad, big and small, teacher and student.

China is populated with many unusual and exciting animals. They certainly could not know so long ago just what species would excite the rest of the world? My link covers but a small collection of exciting creatures of China.

My guess is the Chinese developed their zodiac during a time when the existence of pandas were not yet well known over there.