| 论文摘要 |
The giant panda, currently restricted to a small region of central China, was once widely dispersed throughout southern China and even some parts of continental Southeast Asia during the Pleistocene epoch. However, the evolutionary process and intraspecific variation remain poorly understood in light of limited fossil records, which are usually isolated teeth and a few fragmentary skulls and mandibles. Here we report three skulls, two of which are nearly complete, of Ailuropoda melanoleuca baconi from Yanjinggou in China, which represent the best-preserved skull material ever recorded for this paleosubspecies. A. m. baconi, characterized by a large and robust body, extremely developed zygomatic arches, a moderately developed sagittal crest, and a medium-rough external surface of the supraoccipital, exoccipital, and ascending ramus compared with Ailuropoda microta and other paleosubspecies and living subspecies of A. melanoleuca, can be regarded as a valid paleosubspecies. Ailuropoda fovealis or Ailuropoda melanoleuca fovealis turns out to be a synonym of A. m. baconi. The intraspecific variation of A. m. baconi is far more complicated than generally accepted. Based on comparisons with A. microta, A. m. wulingshanensis, and modern Ailuropoda melanoleuca, we propose that the evolutionary tendency of the skull appears to be much clearer than that of the teeth and that the increase in body size and the enhancement of the masticatory system can be deemed as the main evolutionary changes in this part of the Ailuropoda lineage. Meanwhile, our study for the first time provides a numerical age (ca. 0.35–0.26 Ma) for the Yanjinggou fauna, which is generally considered as a mixture of the middle Early Pleistocene fauna and the Mid-Late Pleistocene fauna. |
