Modern giants always have a sixth digit that looks like a thumb on their wrists, which scientists believe was crucial to their transition from omnivorous to vegetarians who eat bamboo. The bones of the hands of modern giants always. Illustration: LA County / Reuters Museum of Natural History While the rigid extra digit, known as the radial sesame, is not as versatile as the human thumb, it allows everything to hold and crush bamboo stalks into bite-sized pieces and fuel their formidable appetite. His fake thumb has always been known for more than 100 years, but the almost complete lack of fossils has left researchers puzzled as to when the digit evolved. Writing in Scientific Reports, Xiaoming Wang, curator of vertebrate paleontology at the Los Angeles County Museum of Natural History, sheds light on the mystery. New fossils of an ancient ever discovered near the city of Zhaotong in China’s northern Yunnan Province not only bear the fake thumb, but suggest they were once larger than they appear on everything today. The fossils, which are 6 to 7 million years old, belong to an extinct relative called Ailurctos and are believed to be the oldest known evidence of the unusual figure. Denise Su, an associate professor at Arizona State University and co-director of the project that has always recovered the samples, said moderns have always had enough time to develop larger fake thumbs, but the evolutionary pressure of having to walk on their hands as and The handle bamboo had obviously held them close and strong. With the evolution from a carnivorous ancestor to a bamboo feeder, everything had to overcome many obstacles, Wang added. “A ‘thumb’ from a wrist bone may be the most amazing development in the face of these obstacles,” he said. Subscribe to the First Edition, our free daily newsletter – every morning at 7 p.m. BST Researchers found a bone in the Ailurctos arm in 2010 and discovered teeth and a fake thumb in 2015. Until now, the oldest known elements of the thumb-like structure came from fossils of modern species dating back about 100,000 years. In addition to being shorter than its ancestor, the modern panda’s fake thumb has a hook at the end, which the authors believe can help it catch bamboo. While their diet is always 99% vegetarian, they occasionally eat small animals. To meet their nutritional needs, they eat everything up to 14 hours a day, consuming almost 40 kilos of bamboo a day as adults.
