Abstract: Early Paleogene mesonychid specimens, recently collected from the Huheboerhe area and Bayan Ulan, eastern Erlian Basin, Nei Mongol (Inner Mongolia), are described in this paper. They represent six species and four genera, a few of the specimens are specifically indeterminate. Mesonyx nuhetingensis sp. nov., from the basal Arshanto Formation, differs from previously known species of Mesonyx in p4 being the longest lower cheek tooth and weak lingual cingula being present on p3 and p4, respectively. Other mesonychid specimens described in this paper are referred toDissacus serratus, Dissacus sp., Mesonyx uqbulakensis, Mongolonyx dolichognathusand Harpagolestes leei. General evolutionary trends seen in mesonychids from theErlian Basin show a gradual increase in body size and a change in feeding habits from active predation to scavenging.

摘要： 描述了近年来发现于内蒙古二连盆地东部呼和勃尔和地区以及巴彦乌兰早古近纪地层中的中兽科化石材料，共计4属6种，包括一个未定种和发现于阿山头组底部的努和廷中兽新种(Mesonyx nuhetingensis sp. nov.)。新种区别于该属其他种的特点是：p4为最长下颊齿以及p3和p4舌侧有弱的齿带。其余属种包括：Dissacus serratus, Dissacus sp., Mesonyx uqbulakensis, Mongolonyx dolichognathus和Harpagolestes leei。总结了该地区中兽演化的总体趋势：体形逐渐大型化，取食习惯从主动捕猎逐渐转向食用腐尸及骨骸。