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记述了内蒙古自治区脑木根乡附近依和苏布地点产出的 4种兔形类上下颊齿化石。依和苏布位于脑木根乡东南约 1 8km处 ,乌兰希热平台北缘 ,地理坐标为N42°36.1 1 4′,E1 1 1°34.5 96′。依据化石组合 ,该点地层年代初步定为晚始新世。 4种兔形类分别是 :Gobiolagusmajor、Hypsimylusyihesubuensissp .nov.、Desmatolaguscf.D .vetustus以及Desmatolagussp .。新发现的Gobiolagusmajor下颊齿和该种产自沙拉木伦地区乌兰戈楚层的正型标本(AMNH 2 60 98)在大小和形态上很相似 :齿冠较低 ,侧沟不伸入齿槽 ,三角座唇侧较舌侧短 ;m2跟座明显大于m1跟座 ;舌侧有釉质脊连接三角座和跟座。根据个体大小和相对低冠的颊齿 ,我们将一块带P3～M2的上颌骨归入Gobiolagusmajor,成为该种上臼齿的首次记录。上颌骨腭面门齿孔后缘与P3前缘齐 ,硬腭后缘止于M1与M2间位置 ,无前臼齿孔。P3～M2均具三齿根 ,唇侧两齿根小。P4非臼齿化 ,前后脊完全 ,封闭一V形新月谷。M1嚼面椭圆状 ,舌侧内沟短浅。后脊与舌侧的磨蚀面相连 ,其前方的横向谷应为三角座凹。前、后脊唇侧端应分别相当于前、后尖。Hypsimylusyihesubuensissp .nov .是继北京长辛店北京种后该属的第 2个记录。新种较H .beijingensis大 ,齿冠较低 ,m1较宽。下颊齿高冠
Described in the Inner Mongolia Autonomous Region brain wood root Township near the Soviet Union and the Soviet Union to produce four kinds of rabbit-shaped buccal fossils. Yihe Subu is located at about 18 km southeast of Nvmutang Township, at the northern edge of Ulanjai Thermal Platform with the geographical coordinates of N42 ° 36.1 1 4 ’and E1 11 ° 34.5 96’. According to the fossil assemblage, the epoch of this point was initially set as Late Eocene. The four species of rabbits are: Gobiolagus major, Hypsimylusyihesubuensissp. Nov., Desmatolaguscf. D.vetustus, and Desmatolagussp. The newly discovered Gobiolagus major cheek tooth and the positive specimen (AMNH 2 60 98) from the Urango Chu layer in the Sara Moulin area are very similar in size and morphology: the crown is lower and the ditch does not extend into the tooth Groove, triangular lip side shorter than the lingual; m2 with seat significantly greater than the m1 with the seat; lingual enamel ridge connected with the triangular seat and the seat. Depending on the size of the individual and the relatively low-crowned cheek teeth, a maxillary bone with P3-M2 was assigned to Gobiolagus major as the first record of such molar. The posterior edge of the maxillary palatal incision was aligned with the P3 anterior margin, and the posterior edge of the hard palate stopped at the position between M1 and M2 without premolar holes. P3 ~ M2 are tridentate roots, labial two teeth small. P4 non-molars, before and after the ridge completely closed a V-shaped Crescent Valley. M1 chewing oval-like, lingual groove short. Posterior ridge and the lingual side of the erosion surface is connected to the front of the horizontal valley should be triangular seat concave. The anterior and posterior labial side should correspond to the anterior and posterior pointers respectively. Hypsimylusyihesubuensissp. Nov. Is the second Beijing Chang Xindian Beijing genus after the second record. The new species is larger than H. Beijingensis, the crown is lower and m1 is wider. Under the cheek tooth crown