新疆准噶尔盆地早中新世的最早众古仓鼠及其与稀古仓鼠的对比(英文)

记述了新疆准噶尔盆地早中新世地层中发现的众古仓鼠类化石。材料采集于索索泉组的两个地点,古地磁年龄介于21.9～21.16Ma之间。这是迄今为止中亚和东亚地区众古仓鼠的最早记录。材料可以归入两个种:苏氏众古仓鼠(新种)Democricetodon sui sp.nov.和众古仓鼠未定种Democricetodon?sp.,该未定种材料很少,不足以准确分类。与早中新世其他仓鼠的比较及对稀古仓鼠Spanocricetodon模式种的重新观察表明,苏氏众古仓鼠是中亚地区谢家期的指示性化石,李传夔(1977)所定义的稀古仓鼠为一个有效属,与Democricetodon和Primus属有明显区别;以前归入稀古仓鼠的某些种类应归入其他属。苏氏众古仓鼠与同一地区晚渐新世的Eucricetodon aff.E.caducus形态明显不同,表明它可能不是起源于该地区的古近纪仓鼠,而是迁移至中亚的外来种。

EARLIEST OCCURRENCE OF DEMOCRICETODON IN CHINA, IN THE EARLY MIOCENE OF THE JUNGGAR BASIN (XINJIANG) , AND COMPARISON WITH THE GENUS SPANOCRICETODON

New Democricetodon fossils from the Early Miocene of the Junggar Basin(northern Xinjiang,China) are described.The specimens come from two localities within the Suosuoquan Formation,which have been dated by magnetostratigraphy to between 21.9 and 21.16 Ma(Aquitanian).This record of Democricetodon is the oldest so far known in Central and Eastern Asia.Two species are recognized:Democricetodon sui sp.nov.and Democricetodon? sp.The second species is based on few specimens,insufficient for secure taxonomic identification.Comparisons with other Early Miocene cricetids and reexamination of the type species of Spanocricetodon confirm that D.sui is characteristic of the Xiejian age in Central Asia.Our comparisons also confirm that the genus Spanocricetodon sensu lato Li(1977) is valid and clearly differs from Democricetodon and Primus,and show that some species that have previously been assigned to Spanocricetodon actually belong to other genera.The clear differences between D.sui and Eucricetodon aff.E.caducus from the Late Oligocene of the same region indicate that D.sui is unlikely to have originated from the Paleogene cricetids in the region,but probably represents a species that immigrated to Central Asia.