尖吻兽(Akidolestes)的齿列和头后骨骼

Morphology of Dentition and Postcranial Skeleton of Akidolestes

尖吻兽(Akidolestes)是新近在中国辽宁省下白垩统义县组地层发现的对齿兽动物,保存了非常完整的头后骨骼。其齿列特征表明它属于鼹兽超科(Spalacotheroidea)中的鼹兽科动物(Spalacotheriidae),该科是以臼齿齿尖呈对称三角形排列、上下臼齿反转咬合为特征的单系类群,是现生兽类(有袋类和有胎盘类)的近亲,拥有许多兽类骨骼的原始特征。尖吻兽区别于张和兽科的特征是具有更宽大的下颌冠状突和臼齿齿尖呈更小的锐角排列。对尖吻兽的骨骼解剖学和比较形态特征的研究,表明尖吻兽演化模式是一种镶嵌式的,保留有原始特征并初具进步的特征的雏形,并且它很可能是兼有攀援和陆栖哺乳动物的运动方式,可能是同时兼有两种习性的一般性哺乳动物。

Akidolestescifellii Li and Luo, 2006 （NIGPAS 139281A, B） is a new symmetrodont mammal with complete postcranial skeleton discovered in Yixian Fromation, Lower Creatacous, Liaoning province, China. It has been diagnosed as a member of family spalacotheriidae included in superfamily spalacotheroidea. The spalacotheriidae is a monophyletic group; characteristic by the reversed triangular molar. It is the close relative to extant therians （metatherians and eutherians）, with a lot of primitive features. Akidolestes differs from zhangheotheriids in having much broader coronoid process of dentary and more acute angled molars. The skeletal anatomical and morphological comparative study indicates that the evolution of Akidolestes is mosaic pattern combing the primitive and the derived skeletal features. Akidolestes probably shares both terrestrial and arboreal locomotory adaptation, but it is not specialized in either aspects.