云南曲靖晚始新世的梳趾鼠类化石(英文)

根据新材料修订了Ｄｉａｎｏｍｙｓ属及其两个种（Ｄ． ｏｂｓｃｕｒａｔｕｓ和Ｄ． ｑｕｊｉｎｇｅｎｓｉｓ）的鉴定特 征。原定为Ｄ、ｏｂｓｃｕｒａｔｕｓ的Ｐ４应为ｄＰ４，原定的Ｍ１／２和ｍ１／２分别被确认为Ｍ１和ｍ２，原属 Ｄ．ｏｂｓｃｕｒａｔｕｓ的ｐ４，实属Ｄ．ｑｕｊｉｎｇｅｎｓｉｓ。Ｄ．ｑｕｊｉｎｇｅｎｓｉｓ与Ｄ．ｏｂｓｃｕｒａｔｕｓ的区别除个体较大 外，还在于其上颊齿具分叉的后脊，ｍ１具下中脊和ｐ４具较发育的附加刺。另建立了一新属 （杨氏鼠Ｙｏｕｎｇｏｍｙｓ），包括二新种（云南杨氏鼠Ｙ ．ｙｕｎｎａｎｅｎｓｉｓ、小杨氏鼠Ｙ ｐｉｓｉｎｎｕｓ）和一未 定种（Ｙｏｕｎｇｏｍｙｓ？ｓｐ．）。ｙｏｕｎｇｏｍｙｓ的主要特征为：颊齿比例上较窄长，齿冠较低，主尖钝，脊 较细而低；上臼齿长大于宽，后脊向原尖斜伸，内脊较低；下臼齿下原尖后臂较向后伸，无明显 的舌部，下内尖臂很弱，横向，不与下外脊连等。 Ｙ ｐｉｓｉｎｎｕＳ与 Ｙ ｙｕｎｎａｎｅｎｓｉｓ的区别在于个体 较小，齿冠较低，脊更细弱，较显丘形，上臼齿次尖位置向舌侧移，具较明显的后小尖，和后脊 不与原尖连等。 用ＰＡＵＰ ３．１．１对亚洲古近纪的梳齿鼠类进行了系统分析，表明第四前臼齿的

LATE EOCENE CTENODACTYLOIDS (RODENTIA, MAMMALIA) FROM QUJING, YUNNAN, CHINA

The diagnoses of Dianomys, D. obscuratus and D. qujingensis are revised based on new material. The tooth originally described as P4 of D. obscuratus is actually dP4, M1 / 2 and m1 / 2 are M1 and m2 respectively, and the N referred to D. obscuratus is transferred to D. qujingensis. D. qujingensis differs from D.obscuratus not only by larger size, but also in having forked metaloph on upper cheek teeth, mesolophid on m1, and more developed accessory crests in the mesosinusid on p4. A new genus, Youngomys, is erected to include two new species (Y yunnanensis and Y pisinnus) and Youngomys? sp. The main characters of Youngomys include: cheek teeth being long and low crowned, having obtuse main cusps and slender lophs; upper molar being longer than wide, having metaloph oblique to protocone and low entoloph; on lower molar rather posteriorly extended posterior arm of protoconid lacking lingual part, and arm of entoconid weak. Y pisinnus differs from Y yunnanensis in smaller size, cheek teeth being lower crowned and more bunodont, upper molar having more lingually positioned hypocone relative to protocone, distinct metaconule and metaloph separated from protocone. The phylogenetic relationships of the Paleogene Ctenodactyloidea are analyzed based on the dental features using PAUP 3.1.1. It seems that the evolutionaly process of the molariform or non-molariform of the fourth premolars is complex and may have occurred parallel in different lineages. Youngomys has close relationship with Mergenomys. Dianomys is a ctenodactyloid and may be a sister group to Mergenomys + Youngomys group plus the Ctenodactylidae.