12/26/2023 0 Comments Thumbs up panda![]() ![]() "Tightly holding bamboo stems in order to crush them into bite sizes is perhaps the most crucial adaptation to consuming a prodigious quantity of bamboo." "Deep in the bamboo forest, giant pandas traded an omnivorous diet of meat and berries to quietly consuming bamboos, a plant plentiful in the subtropical forest but of low nutrient value," says NHM Vertebrate Paleontology Curator Dr. Uncovered at the Shuitangba site in the City of Zhaotong, Yunnan Province in south China and dating back 6–7 million years ago, a fossil false thumb from an ancestral giant panda, Ailurarctos, gives scientists a first look at the early use of this extra (sixth) digit–and the earliest evidence of a bamboo diet in ancestral pandas–helping us better understanding the evolution of this unique structure. While the celebrated false thumb in living giant pandas (Ailuropoda melanoleuca) has been known for more than 100 years, how this wrist bone evolved was not understood due to a near-total absence of fossil records. In a new paper published in Scientific Reports, the Natural History Museum of Los Angeles County's Curator of Vertebrate Paleontology Xiaoming Wang and colleagues report on the discovery of the earliest bamboo-eating ancestral panda to have this "thumb." Surprisingly, it's longer than its modern descendants. This unique adaptation helps these bears subsist entirely on bamboo despite being bears (members of the order Carnivora, or meat-eaters). Through its long evolutionary history, the panda's hand has never developed a truly opposable thumb and instead evolved a thumb-like digit from a wrist bone, the radial sesamoid. ![]() When is a thumb not a thumb? When it's an elongated wrist bone of the giant panda used to grasp bamboo. ![]() The grasping function of its false thumb (shown in the right individual) has reached to the level of modern pandas, whereas the radial sesamoid may have protruded slightly more than its modern counterpart during walking (seen in the left individual). An artist reconstruction of Ailurarctos from Shuitangba. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |