Abstract: Aprotodon, a group of mid—Tertiary rhinoceroses with particularly wide symphyses, was previously known only from Pakistan and Kazakhstan. Its affinity has been little understood because of the paucity of the fossils available for study. The senior author of the present paper first mentioned its occurrence in the Lanzhou basin in 1990. In fact, its first finding was made early in 1986. In that year the junior author of the present paper collected some isolated teeth of this genus from Zhangjiaping, about 10km north of Lanzhou. Later in 1988 a well—preserved lower jaw with characteristic Aprotodon huge tusks was unearthed from a layer of thick white sandstone near the village Duitinggou, 10krn east of niangjiaping. Various specimens, including skull fragments and upper teeth attributable to Aprotodon, have been found in the Lanzhou basin since then. Now Aprotodon became the best represented genus among the large fossil mammals of the Lanzhou basin, and our knowledge of this genus is considerably augmented owing to these findings. The material to be studied below is important not only for the age determination of the Cenozoic deposits in the Lanzhou basin, but also for a better understanding of the genus Aprotodon.

摘要： 本文记述的兰州巨獠犀新种(Aporotodon lanzhouensis sp. nov.)是这个属在我国的首次发现。新种以第二下门齿特别粗大、强烈弯曲而区别于哈萨克斯坦的A. aralensis。兰州材料中有与联合部连在一起的下颌支，这使我们第一次确切了解到该属下颌及下颊齿的形态特征。Aprotodon不是Teleoceratinae的成员。它和Symphysorrachis在形态上更为接近。它可能是真犀科中较早分出来的单独一支。