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Earliest giant panda false thumb suggests conflicting demands for locomotion and feeding Project ID: 000397698 Public
2 Media · 2 Specimens · Creator: Xiaoming Wang · Managed by: Xiaoming Wang

Wang, X., D. F. Su, N. G. Jablonski, X. Ji, J. Kelley, L. J. Flynn, and T. Deng. 2022. Earliest giant panda false thumb suggests conflicting demands for locomotion and feeding. Scientific Reports 12(1): 10538. Abstract: Of the many peculiarities that enable the giant panda (Ailuropoda melanoleuca), a member of the order Carnivora, to adapt to life as a dedicated bamboo feeder, its extra “thumb” is arguably the most celebrated yet enigmatic. In addition to the normal five digits in the hands of most mammals, the giant panda has a greatly enlarged wrist bone, the radial sesamoid, that acts as a sixth digit, an opposable “thumb” for manipulating bamboo. We report the earliest enlarged radial sesamoid, already a functional opposable “thumb,” in the ancestral panda Ailurarctos from the late Miocene site of Shuitangba in Yunnan Province, China. However, since the late Miocene, the “thumb” has not enlarged further because it must be balanced with the constraints of weight bearing while walking in a plantigrade posture. This morphological adaptation in panda evolution thus reflects a dual function of the radial sesamoid for both bamboo manipulation and weight distribution. The latter constraint could be the main reason why the panda’s false thumb never evolved into a full digit. This crude “thumb” suggests that the origin of the panda’s dedicated bamboo diet goes back to as early as 6–7 Ma.

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  ID Part Object Taxonomy Type Date Added Publication Status  
000448542 radial sesamoid yicra:zt:2015–0056 Ailurarctos lufengensis Mesh 2022-06-29 Open Download  
000448536 Upper M2 yicra:zt:2015–0124 Ailurarctos lufengensis Mesh 2022-06-29 Open Download  
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