Abstract: The ischyromyids are the most primitive rodents that have a Holarctic Paleogene distribution. Members of the family are predominant in Paleogene rodents of North America, but are relatively rare in both Asia and Europe. Here we report some new material of the Eocene ischyromyids from the Huheboerhe area in the Erlian Basin, Nei Mongol, China. These include Asiomys dawsoni from the basal strata of the Irdin Manha Formation and Ischyromyidae gen. et sp. indet. from the basal strata of the Arshanto Formation. The new materials include fragmentary mandibles and numerous cheek teeth, which provide new evidence for mammal's dispersal between Asia and North America during the Middle Eocene.

摘要： 描述了产自内蒙古二连盆地呼和勃尔和地区始新世壮鼠类化石，包括呼和勃尔和剖面伊尔丁曼哈组底部的Asiomys dawsoni以及努和廷勃尔和剖面阿山头组底部的Ischyromyidae gen. et sp. indet.。其中Asiomys与其他壮鼠类的区别在于其下颌厚、高；咬肌窝明显、前缘宽，并有较明显的结节；P4无次尖、M1和M2次尖小；后小尖2个；dp4有明显的下次脊、p4无下次脊；下臼齿下原尖后棱长短不一、下次尖与下后齿带相连、下外脊完整、下次脊短。Asiomys的下颌特征与Paramys delicatus相似，门齿釉质层、上臼齿次尖、下臼齿下次脊等结构特征与北美中始新世的壮鼠类相近，与亚洲已知的壮鼠类差别较大。因此，Asiomys是中始新世亚洲与北美大陆哺乳动物之间交流的又一佐证。