贵州剑河寒武系苗岭统凯里组太阳女神螺类几何形态学研究

Morpho-geometric analysis of helcionelloid mollusks from the Kaili Formation(Miaolingian,Cambrian),Jianhe,Guizhou

太阳女神螺类(helcionellids)是寒武纪常见的一类软体动物,广布全球,多见于碳酸盐岩沉积地层中,而布尔吉斯页岩型生物群中却少有报道。贵州剑河凯里生物群是典型的特异埋藏化石库,产有700余件太阳女神螺类标本,这在世界各地同时期的布尔吉斯页岩型生物群中是很少见的。本文对贵州剑河八郎寒武系凯里组太阳女神螺类化石标本进行了系统研究,采用几何形态测量学的典型变量分析进行量化分析。几何形态测量学(Geometric morphometrics)是用界标点或轮廓线等来描绘生物的形态或者标记特征部位及器官,将生物形态特征归纳为数据变化的定量学方法,其中的典型变量分析(Canonical Variate Analysis)是多变量分析中进行判别分析的一个重要方法,可以用于多组数据之间的判别。CVA判别结果显示:利用壳体侧视轮廓线判别Dorispira属中三个种的正确率为92%,验证了Dorispira accordinonata、D.taijiangensis和D.cf.pearylandica化石种分类合理性。本文研究表明即使壳体形态较为相似的类群,也可以较为准确地使用CVA量化其中的差别,从而为几何形态测量学应用于系统古生物分类提供定量化的参考。

The helcionellids are common mollusks of the Cambrian.They occur in Cambrian strata all over the world,but they are mostly found in carbonate depositional settings and are rarely reported in Burgess Shale-type faunas.The Kaili Biota in Jianhe,Guizhou Province is a typical exceptionally preserved fossil Lagerstätte.With more than 700 specimens of helcionellids collected,it is particularly noteworthy among the Cambrian Burgess Shale-type faunas.Herein,helcionelloid mollusks from the Kaili Biota were analyzed using canonical variate analysis(CVA)of the geometric morphological method.Geometric morphometrics refers to a quantitative analysis of organism morphology and specific marked parts.As an important method for multivariate analysis,CVA can be used to discriminate differences between data sets.Results of CVA show that,by analyzing the lateral outline of the specimens of Dorispira,the accuracy rate of identifying the three species,i.e.,Dorispira accordinonata,D.taijiangensis,and D.cf.pearylandica is 92%,which is consistent with morph-based classifications of the genus.This work demonstrates that CVA can be used to quantify the differences between species with relatively similar morphology,thus providing a quantitative reference for the application of geometric morphometry in taxonomic studies.