First discovery of fossil Diplothrix (Muridae, Rodentia) outside the Ryukyu Islands, Japan  

作　　者：WANG Yuan1,2, JIN ChangZhu1 & WEI GuangBiao3,41 Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China 2 Graduate University of Chinese Academy of Sciences, Beijing 100049, China 3 Chongqing Three Gorges Institute of Paleoanthropology, China Three Gorges Museum, Chongqing 400015, China 4 Chongqing Three Gorges Culture and Social Development Research Institute, Chongqing Normal University, Chongqing 400047, China 

出　　处：《Chinese Science Bulletin》2010年第4期411-417,共7页

基　　金：supported by the Key Knowl-edge Innovation Project of the Chinese Academy of Sciences (Grant No. KZCX2-YW-106);Major Basic Research Projects of MST of China (Grant No. 2006CB806400);National Natural Science Foundation of China (Grant No. J0630965)

摘　　要：The first Diplothrix (Muridae, Rodentia) fossils of the early Early Pleistocene are described as D. yangziensis sp. nov., which were collected from the Renzidong Cave deposits in Anhui Province, Eastern China. Diplothrix was previously represented by a single species, D. legata, whose geographical distribution during the Late Pleistocene is restricted to the Ryukyu Islands, Japan. With straight chevrons on M1, distinct t3 and t9 on upper molars, primitive M3, mlc on m1, and developed a-lab on m2 and m3, the new species is morphologically distinct from other large murids in East Asia, and should belong to the genus Diplothrix. There are also differences in molar morphology between the new species and D. legata, the type species of Diplothrix, as well as other known fossils. For example, D. yangziensis sp. nov. has a smaller size, a more elongated crown, developed precingulum and pc on M1, more primitive M3, weaker mlc and more primitive pc on m1, and stronger plc and pc on m3. In short, Diplothrix yangziensis sp. nov. is evidently more primitive than D. legata, suggesting that the former is likely the ancestor of the latter. Diplothrix yangziensis sp. nov. is the first discovery of the genus outside the Ryukyu Islands, Japan and is also the earliest and most primitive species of the genus in Eurasia. Its discovery has significant implications for reconstructing the evolution and dispersal pattern of Diplothrix, as well as for discussing its palaeoecological variation.The first Diplothrix （Muridae, Rodentia） fossils of the early Early Pleistocene are described as D. yangziensis sp. nov., which were collected from the Renzidong Cave deposits in Anhui Province, Eastern China. Diplothrix was previously represented by a single species, D. legata, whose geographical distribution during the Late Pleistocene is restricted to the Ryukyu Islands, Japan. With straight chevrons on M1, distinct t3 and t9 on upper molars, primitive M3, mlc on ml, and developed a-lab on m2 and m3, the new species is morphologically distinct from other large murids in East Asia, and should belong to the genus Diplothrix. There are also differences in molar morphology between the new species and D. legata, the type species of Diplothrix, as well as other known fossils. For example, D. yangziensis sp. nov. has a smaller size, a more elongated crown, developed precingulum and pc on M1, more primitive M3, weaker mlc and more primitive pc on ml, and stronger plc and pc on m3. In short, Diplothrixyangziensis sp. nov. is evidently more primitive than D. legata, suggesting that the former is likely the ancestor of the latter. Diplothrixyang- ziensis sp. nov. is the first discovery of the genus outside the Ryukyu Islands, Japan and is also the earliest and most primitive species of the genus in Eurasia. Its discovery has significant implications for reconstructing the evolution and dispersal pattern of Diplothrix, as well as for discussing its palaeoecological variation.

关 键 词：琉球群岛 化石 日本 鼠科 形态差异 供应量 早更新世 中国东部 

分 类 号：Q915[天文地球—古生物学与地层学]