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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.

At 50 kg in estimated weight, the extinct Siamogale melilutra is larger than all living otters, and ranks among the largest fossil otters. The biomechanical capability of S. melilutra jaws as related to their large size is unknown but crucial to reconstructing the species' potentially unique ecological niche. Here we compare the mandibular biomechanics of S. melilutra using engineering-based performance measures against ten extant otter biomechanical models. Despite a wide range of feeding preferences from durophagy to piscivory, living otter species exhibit a linear relationship between mandible stiffness and volume, as expected in isometric model scaling. In contrast, S. melilutra models exhibit a six-fold increase in stiffness from expected stiffness-volume relationships calculated from extant species models. Unlike stiffness, mechanical efficiency of biting is conserved among living otters and in S. melilutra. These findings indicate that although similar to living bunodont otters in morphology and biting efficiency, jaw strength in S. melilutra far surpasses molluscivores such as sea otters and Cape clawless otters, even after accounting for size. Therefore, Siamogale represents a feeding ecomorphology with no living analog, and its giant size and high mandibular strength confer shell-crushing capability matched only by other extinct molluscivores such as the marine bear Kolponomos.

At 50 kg in estimated weight, the extinct Siamogale melilutra is larger than all living otters, and ranks among the largest fossil otters. The biomechanical capability of S. melilutra jaws as related to their large size is unknown but crucial to reconstructing the species' potentially unique ecological niche. Here we compare the mandibular biomechanics of S. melilutra using engineering-based performance measures against ten extant otter biomechanical models. Despite a wide range of feeding preferences from durophagy to piscivory, living otter species exhibit a linear relationship between mandible stiffness and volume, as expected in isometric model scaling. In contrast, S. melilutra models exhibit a six-fold increase in stiffness from expected stiffness-volume relationships calculated from extant species models. Unlike stiffness, mechanical efficiency of biting is conserved among living otters and in S. melilutra. These findings indicate that although similar to living bunodont otters in morphology and biting efficiency, jaw strength in S. melilutra far surpasses molluscivores such as sea otters and Cape clawless otters, even after accounting for size. Therefore, Siamogale represents a feeding ecomorphology with no living analog, and its giant size and high mandibular strength confer shell-crushing capability matched only by other extinct molluscivores such as the marine bear Kolponomos.

The fossil tapirid records of Late Miocene and Early Pliocene were quite poor in Chinaas before known. The recent excavations of the terminal Miocene hominoid site (between 6 and6.5 Ma) at Shuitangba site, Zhaotong in Yunnan Province resulted in the discovery of rich tapirfossils, which include left maxilla with P2-M2 and mandibles with complete lower dentitions.The new fossil materials can be referred to Tapirus yunnanensis, which represents a quite small species of the genus Tapirus. But T. yunnanensis is slightly larger than another Late Miocenespecies T. hezhengensis from Gansu, northwest China, both of which are remarkably smallerthan the Plio-Pleistocene Tapirus species in China. The new fossils provided more information todefine the species T. yunnanensis more precisely. Yunnan can be regarded as one of the centers oftapir evolution during the Mid-Late Miocene period, as quite a number of Mid-Late Miocene tapirfossils have been recovered in several localities of Yunnan, which include Xiaolongtan, Yuanmou,Lufeng, Zhaotong and others. Based on the measurements of tooth size, the late Cenozoic tapirswere generally getting larger gradually through time in China, which means the tooth sizescoincide well with their geological ages, the later the larger, and all the Mid-Late Miocene tapirsare exclusively small-sized; thus, the tooth size of fossil tapirs in China is likely to have somesignificance in age estimation. By contrary, both the dwarf and the normal-sized or larger-sizedtapirs were discovered from Mid-Late Miocene strata in Europe and North America.