南澜沧江带中三叠世叶肢介化石的发现及形态学研究
Biostratigraphy and Geometric Morphometrics of Conchostracans from the Middle Triassic in Southern Lancangjiang Zone

三叠纪火山-沉积岩是南澜沧江带的重要组成部分，长期缺乏可靠的生物地层学研究.首次报道了该地区忙怀组叶肢介化石，包括3个种和1个未定种：Euestheria minuta、Euestheria yipinglangensis、Euestheria dazuensis和Euestheria sp..对保存较好的叶肢介个体进行了8个特征参数的测量，并对叶肢介化石进行了定量和半定量描述.将获得的壳体长度和宽度进行压轴回归(RMA)线性拟合，发现二者具有明显的线性相关性.简单线性测量数据主成分分析和壳体轮廓傅里叶系数主成分分析结果均表明， E.minuta、E. sp.、 E.yipinglangensis和E.dazuensis有较大程度的种内变化.结合化石组合和同位素测年结果，认为南澜沧江带忙怀组上部时代已延伸至中三叠世拉丁期.
The Triassic volcanic and sedimentary rocks are the important components in the geological records of the southern Lancangjiang zone.However, little is known about the biostratigraphic correlation in this area.In this study, three species and one indeterminate species in one genera of conchostracans were recognized for the first time from the Manghuai Formation of the study area, including Euestheria minuta, Euestheria yipinglangensis, Euestheria dazuensis and Euestheria sp.. For the purpose of the comparison, quantitative and semi-quantitative descriptions of the specimens, we took eight standard linear measurements from each well-preserved specimen.A reduced major axis (RMA) regression line has been fitted to the scatter of carapace length versus carapace height, showing a significant linear correlation between them.In addition, the principal component analysis of the linear measurements and fourier coefficients for the outlines of the conchostracan specimens indicates a great deal of intraspecific variations among these four species.Finally, it is suggested that the upper part of the Manghuai Formation in the southern Lancangjiang zone is the Middle Triassic (Ladinian) depositions according to the fossils assemblage and isotopic dating evidences