豫鼠化石在我国阿尔金地区的发现

记述了在新疆巴音郭楞蒙古族自治州若羌县阿尔金山地区彩虹沟首次发现的豫鼠一新种:阿尔金豫鼠(Yuomys altunensis sp.nov.).其主要特征是臼齿的尺寸较大,比例上较宽,齿冠较高,臼齿的后小尖与后尖明显分开,后脊相对较长,但不完全,次尖明显小于原尖,舌侧内凹伸达臼齿齿冠基部,后齿带与后尖舌侧连;M3后尖为新月形,后齿带较短等.根据豫鼠臼齿的进化趋势和新种臼齿的尺寸较大、齿冠较高和舌侧内凹伸达齿冠基部的特征与Y.cavioides,Y.eleganes和Y.huangzhuangensis相近,但颊齿比例较宽判断,Y.altunensis可能与该3种处于同样的进化阶段或稍进步.其产出的地层时代很可能与它们相近或稍晚,即为晚中始新世或稍晚.

Discovery of Yuomys from Altun Shan,Xinjiang, China

Specimens reported in this note represent the first discovery of Yuomys in Altun Shan.A new species,Yuomys altunensis,is established based on the following features:molars large and wide in proportion;metaconule distinctly separated from metacone,metaloph long,but incomplete;hypocone smaller than protocone;sinus extending to base of crown on lingual side;postcingulum connectting lingual side of metacone;metacone crescent and postcingulum short in M3.Yuomys altunensis is similar to Y cavioides,Y.eleganes and Y huangzhuangensis of late Middle Eocene in molar morphlogy.According to its evolutionary level,Y.altunensis is supposed as of late Middle Eocene in age,or slightly later.