论文部分内容阅读
对历年来采自高特格地点3个不同层位的共227件仓鼠类标本进行了分类描述和研究,这些标本可以归入2属3种,分别为进步中华仓鼠Sinocricetus progressus,大中华仓鼠(新种)S.major sp.nov.和蒙古微仓鼠Nannocricetus mongolicus。作为内蒙古中部地区新近纪动物群序列中的最晚代表,上新世高特格动物群存在一些特有的进步的小哺乳动物种类,S.major新种就是仓鼠类中的一例。大中华仓鼠新种特征为:个体显著大,齿冠高,下臼齿发育有较发达的(假)下中脊,其中m1的下中脊指向前内方向,m2的假下中脊(或称下原尖后臂)前内向与下后尖后壁连接。古地磁的测定表明,Sinocricetus progressus和Nannocricetus mongolicus在高特格剖面上的年限大致为4.2～3.9Ma,S.major只出现于剖面下部,其年限约为4.2Ma.Sinocricetus和Nannocricetus两属目前主要发现于中国北方晚中新世早期至最晚上新世的地层中,它们可能都是中国特有的新近纪仓鼠。对内蒙古中部地区最晚中新世二登图和哈尔鄂博、早上新世比例克和高特格地点的材料对比表明,Sinocricetus牙齿特征可能存在如下演化趋势:M1-2原脊I发育频率逐渐增高,M1-2的中脊与后尖前壁连接的程度逐渐增高,m1下前脊从双支分别与唇舌两侧下前边小尖连接向单支与唇侧下前边小尖连接转变,以及m2的假下中脊与下后尖后壁发生连接的频率逐渐增高。Nannocricetus在其演化中牙齿形态变化可能存在的趋势是:M1-2的牙根数由3增加到4,M1-2的后小脊II逐渐退化消失,m1的下前边尖逐渐收缩变窄和分裂,M2-3和m2-3的舌侧(下)前边脊逐渐退化消失,及m3下中脊出现频率逐渐增高。
A total of 227 hamster samples collected from three different horizons in the Gochig location were classified and studied in this paper. These samples can be classified into two genera and three species: Sinocricetus progressus, Greater Chinese hamster New species) S. major sp. Nov. And Mongolian hamster Nannocricetus mongolicus. As the latest representative of the Neogene fauna sequence in central Inner Mongolia, there are some endemic and progressive small mammal species in the Upper Pleistocene. The new S. major species is an example of a hamster. The characteristics of new species of Hamster in Greater China are as follows: the individual is large, the crown of the tooth is high, the more developed (false) lower middle ridge is developed in the lower molars, the lower middle ridge of m1 points in the anteromedial direction, Under the original sharp rear arm) before the back of the posterior and posterior wall connection. Paleomagnetism measurements show that Sinocricetus progressus and Nannocricetus mongolicus have a maximum age of 4.2-3.9 Ma on the Gogh profile and S. major appears only at the lower part of the profile with an age of about 4.2 Ma. The two major genera of Sinocricetus and Nannocricetus are currently found In northern China from the Late Miocene to the latest Pleistocene strata, they may all be endemic to Neogene hamsters. A comparison of the materials of the late Neocene Erdende and Halboube, the morning Pliocene and the Göttinge in the central Inner Mongolia shows that the Sinocricetus dental characteristics may have the following evolutionary trends: M1-2 Increased, the midpoint of M1-2 and the posterior apical wall connected to the degree of gradually increased, m1 the anterior ridge from the double branch respectively with the lower lip on both sides of the lower anterior tip connection to the single branch and the labial anterior inferior tip connection change, and m2 false hypogastric ridge and posterior apical wall after the occurrence of the connection frequency gradually increased. Nannocricetus in its evolution may be the trend of tooth morphological changes: M1-2 root number increased from 3 to 4, M1-2 small ridge II gradually degenerated disappear, m1 lower frontal tip gradually narrowed and split, The lingual (lower) anterior ridge of M2-3 and m2-3 gradually degenerated and disappeared, and the frequency of lower M3 appeared to increase gradually.