Abstract: Two species of perissodactyls from the upper part of the Nomogen Formation (Bumbanian, Early Eocene) are described: the lophialetid tapiroidMinchenoletes erlianensis gen. et sp. nov., and the hyracodontid rhinocerotoidPataecops parvus. M. erlianensis differs from the known lophialetids in having smaller size, lower crowned cheek teeth, less developed lophs, smaller length/width ratio in M1–2, and proportionally longer M3. Both taxa extend the fossil records of the Lophialetidae and the Rhinocerotoidea to the earliest Eocene. Recent stratigraphic data shows that Minchenoletes is only found from the upper part of the Nomogen Formation (Bumbanian), while Schlosseria and Lophialetes occurred respectively in the Arshanto and the Irdin Manha formations, enhancing their significance in biostratigraphic correlations and understanding of early evolution of perissodactyls. Based on the new stratigraphic data and review of the fieldnote of the CAE we consider that the Mongolian specimens of Pataecops parvus probably came from a lower stratigraphic level than most taxa of the Kholobolchi fauna, possibly correlative to the Bumbanian age.

摘要： 描述了脑木根组上部(早始新世伯姆巴期)两种奇蹄类：脊齿貘类的二连明镇貘(新属新种) Minchenoletes erlianensis gen. et sp. nov.和蹄齿犀类的Pataecops parvus。二连明镇貘区别于其他脊齿貘类的特点是：个体小，颊齿齿冠低，齿脊相对不发育，牙齿较横宽(长宽比小)，M3相对较长。两种化石分别将脊齿貘科和犀超科的化石记录提前到最早始新世。最新的地层资料表明，明镇貘仅发现于脑木根组上部，相当于伯姆巴期的地层中；施氏貘(Schlosseria)和脊齿貘(Lophialetes)则分别发现于阿山头组和伊尔丁曼哈组。因此，这些化石在生物地层对比和早期奇蹄类演化研究中具有重要价值。依据二连地区的新资料和中亚考察团的野外记录，我们认为蒙古的Pataecopsparvus标本可能来自比Kholobolchi动物群大多数种类更低的层位，可能相当于伯姆巴期。