内蒙古始新世梳趾鼠类化石

描述了４属１０种梳趾鼠类化石（Ｇｏｂｉｏｍｙｓ ｎｅｉｍｏｎｇｏｌｅｎｓｉｓ， Ｇ． ｅｘｉｇｕｕｓ（新种）， Ｇ． ｃｆ．Ｇ．ｅｘｉｇｕｕｓ，Ｇ．ａｓｉａｔｉｃｕｓ（新种），Ｇｏｂｉｏｍｙｓ？ｓｐｐ．，Ａｄｖｅｎｉｍｕｓ　ｃｆ．Ａ．ｂｏｈｌｉｎｉ，Ａ．ｃｆ．Ａ．ｂｕｒｋｅｉ， Ｙｕｏｍｙｓ ｓｐ．和Ｐｒｏｔａｔａｒｏｍｙｓ　ｓｐ．）．以Ｍｅｒｇｅｎｏｍｙｓ　ｎｅｉｍｏｎｇｏｌｅｎｓｉｓ作属型种建了一新属，Ｇｏｂｉｏｍｙｓ。其特征是：门齿孔大；具Ｐ３；颊齿齿冠低，主尖明显，但不膨大，齿凹开阔；Ｐ４／ｐ４非臼齿化；上臼齿宽大于长，后脊较发育；Ｍ１和Ｍ２具内脊；下外脊和下次小尖位置偏外。Ｇ．ｅｘｉｇｕｕｓ的特点是：个体较小，上颌骨颧突根在Ｐ３之前，下臼齿缺下原失后臂舌部、下内尖臂和下前齿带．Ｇ．ａｓｉａｔｉｃｕｓ的上颌骨颧突后缘在Ｐ３的外方；臼齿具较发达的齿脊；上臼齿较宽短，后小尖较弱；下臼齿具较发达的内尖臂和前齿带。 Ｇｏｂｉｏｍｙｉｄａｅ新科包括Ｇｏｂｉｏｍｙｓ， Ｍｅｒｇｅｎｏｍｙｓ，Ｙｏｕｎｇｏｍｙｓ和哈萨克斯坦的未命名的新属等４属，组成与梳趾鼠科相对的姐妹群。其主要特征是，下颌骨缺咬肌窝上嵴。颊齿低冠，近于丘形

EOCENE CTENODACTYLOIDS (RODENTIA, MAMMALIA)F ROM NEI MONGOL, CHINA

The ctenodactyloids from the Eocene of Nei Mongol include 10 species representing 4 genera (Gobiomys neimongolensis, G. exiguus sp. nov., G. cf. G. exiguus, G. asiaticus sp. nov., Gobiomys? spp., Advenimus cf. A bohlini, A cf. A. burkei, Yuomys sp. and Protataromys sp.). The new genus, Gobiomys, is erected based on the species, neimongolensis, which has previously been referred to Mergenomy. The main characters of Gobiomys are: incisive foranen large; P3 present cheek teeth lower crowned, with distinct but not swollen main cusps and broad sinuses; P4/p4 non-molariform; upper molars wider than long, with rather developed metaloph; M1 and M2 with entoloph; on lower molars metaconid and entoconid inclining forwards and ectolophid and hypoconulid slightly buccally located. The main features of G. exiguus include small size, zygomatic process of maxillary anterior to P3, absence of lingual part of posterior arm of protoconid, arm of entocoind and anterior cingulum on lower molars. In G. asiaticus the posterior edge of the zygomatic process of maxillary is buccal to P3; the molars have more developed lophs; the upper molars are relatively wide and have weaker methaconule; and the lower molars have more developed arm of entoconid and anterior cingulum. The new family, Gobiomyidae, includes Gobiomys, Mergenomys, Youngomys and Ctenodactyloidea gen. nov. from Kazakhstan [see Wang et al., (MS)]. In the family the lower jaw lacks upper crest of masseteric fossa. The cheek teeth are .brachydont and more bunodont than lophodont. P3 is usually present. P4/p4 are nonmolariform. On the upper molars the protoconule is absent, the metaloph extends towards protocone or absent and the metaconule is usually well-developed. The p4 has no metalophid. On lower molars the posterior arm of protoconid extends rather posteriorly and the arm of entocoind is weak or absent. The ectolophid is near centrally located and has no mesoconid. The Gobiomyidae represent the sister group to the Ctenodactylidae.