How did the panda become a vegetarian? The discovery of a fossil provides the answer

AFP, Posted on Monday, July 04, 2022 at 07:56

The discovery of fossils of a panda ancestor in China has allowed researchers to solve the mystery surrounding the mammal’s “sixth thumb,” which allows it to hold onto the bamboo stalks that make up the bulk of its diet.

The fossils, which are about six million years old, were discovered in Yunnan province in southwest China. Among them is a particularly large carpal bone, called the radial sesamoid.

This is the oldest evidence of a giant panda having a “sixth finger,” which allows it to grasp and break thick bamboo stems, researchers point out in the latest edition of the journal Scientific Reports.

The fossil belongs to a now-extinct panda ancestor known as Ailurarchtos that lived six to eight million years ago in China.

“The giant panda is a rare case of a large carnivore … turned into a herbivore,” said Wang Xiaoming, curator of vertebrate paleontology at the Los Angeles County Museum of Natural History.

“The Ailurarctos ‘false thumb’ shows for the first time (…) the possible chronology and evolutionary stages of bamboo feeding in pandas,” he added.

Although the existence of the “false thumb” was known to researchers over a century ago, the fossil evidence of this bone sheds light on many long-unanswered questions, including how and when this extra finger developed. No other bears have spawned.

Millions of years ago, pandas switched their ancestors’ omnivorous, protein-rich diet to nutrient-poor, year-round bamboo in southern China.

They eat up to 15 hours a day and an adult panda can eat 45 kg of bamboo every day. Although their diet is primarily vegetarian, giant pandas are known to occasionally hunt small animals.