基于居群变异的■种鉴定——以Eopolydiexodina为例

为使■类形态种更接近客观真实的生物种,在■类化石鉴定中应从居群概念出发,利用居群的形态变异特征约束传统的形态鉴定.根据滇西小新寨剖面中二叠世沙子坡组单层采集的样品,笔者度量了其中Eopolydiexodina个体的特征形态参数(初房直径、内外圈尺寸与轴率),并进一步结合形态统计学方法进行了化石居群层次的形态种鉴定.研究结果表明,该单层中Eopolydiexodina个体的特征形态参数虽表现出较大范围的变异,但形态变异基本连续且满足正态分布.因此,所研究个体的形态变异符合单个居群的形态变异特征,宜根据居群思想视作同一■种.本文的研究结果支持了同层产出的同属■类个体组成单个化石居群的假设.

Fusulinid species determination based on population variation:An example from Eopolydiexodina

To make fusulinid morphospecies more accordant with biological species, it is necessary and reasonable to constrain the conventional determination of fusulinid species with population-level morphological variation. As an example, morphospecies identification on population level was conducted on Eopolydiexodina specimens from a single bed of the Middle Permian Shazipo Formation of Xiaoxinzhai Section in western Yunnan, China. These specimens were identified with the consideration of fossil population by morphometric analysis of their characteristic morphological variates (diameter of proloculus, size and ratio of inner and outer volutions). The results reveal that the studied variates have wide but overall continuous variation and generally follow the normal distribution. The studied individuals, therefore, have consistent morphological variation with a single population and should belong to one fusulinid morphospecies. This study supports the assumption that fusulinid individuals of one genus from the same bed in one locality should constitute a single fossil population.

滇西耿马县小新寨中二叠世沙子坡组“Rugososchwagerina”的再研究

中二叠世的Eopolydiexodina-Rugososchwagerina类动物群是一个具有重要地层及古地理意义的动物群,也是滇西保山地块沙子坡组的一个指示性动物群。文中详细研究了耿马小新寨沙子坡组“Rugososchwageri-na”标本的形态学特征,阐明了其与RugososchwagerinaMiklukho-Maklay,1956的模式标本在特征上的显著区别。依据幼壳形态特征在类个体发育及系统发生研究中的重要性,对小新寨“Rugososchwagerina”标本的属级分类提出质疑,并建议建立新属Xiaoxinzhaiellagen.nov.。