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晚奥陶世早期,随着海平面上升,鹦鹉螺逐渐成为海洋中的霸主,中华震旦角石[Sinoceras chinense(Foord)]开始繁盛。迄今为止Sinoceras chinense共记录有8个亚种,主要产出于晚奥陶世早期扬子区宝塔组网纹状灰岩之中。从前人的描述和图版来看,有些亚种与Sinoceras chinense模式标本差别较大,并且一些亚种并存于同一地区同一层位,这与生物学上种和亚种的定义相悖,需要重新厘定。因此,本文在归纳24篇前人文献中关于Sinoceras chinense的所有系统描述资料基础上,对迄今已发表的33个Sinoceras chinense标本选取6个主要壳体形态参数,运用聚类分析等多元统计分析手段,对这些标本的形态特征数据进行定量化分析,认为这些标本可以分为3个组合:Sinoceras chinense chinense组合、Sinoceras chinense eccentrica组合和非Sinoceras chinense组合,从而厘定了有关该种的分类问题,并明确Sinoceras chinense的鉴别特征,进而重新认识Sinoceras chinense的地理分布,认为Sinoceras chinense仅分布在我国华南、云南西部、新疆和西藏等地,华北地区和国外并没有确切的产出记录。
In the late Ordovician, as the sea level rose, the Nautilus became the overlord in the oceans. Sinoceras chinense (Foord) began to flourish. To date, Sinoceras chinense has recorded a total of eight subspecies, mainly occurring in the palaeo-limestone of the Paleotropical Paleontology in the early Ordovician. Judging from previous descriptions and figures, some subspecies differ greatly from the Sinoceras chinense model and some subspecies coexist on the same horizon in the same area, which is contrary to the definition of biological species and subspecies and needs to be redetermined . Therefore, based on the systematic description of Sinoceras chinense from 24 previous papers, we selected six main shell morphological parameters from 33 Sinoceras chinense specimens so far, and used the method of multiple statistical analysis such as cluster analysis , Quantitative analysis of the morphological characteristics of these specimens suggests that the specimens can be divided into three combinations: the Sinoceras chinense chinense assemblage, the Sinoceras chinense eccentrica assemblage and the non-Sinoceras chinense assemblage, thereby determining the classification of the species and clarifying Sinoceras chinense, so as to re-understand the geographical distribution of Sinoceras chinense. Sinoceras chinense is considered to be only distributed in southern China, western Yunnan, Xinjiang and Tibet of China. There is no exact output record in North China and abroad.