Biometrical Study of Morphological Variations of Microfossils in Time and Space

本研究的目的是评价有孔虫、介形类和硅藻等微化石在时间和空间上的形态变化，并阐明微化石在新生代时期的变迁。 1988年，我们安装了最近改进的图像处理器，然后一直致力于选择适合测量和引发上述各组物种间和物种内微化石形态变化的参数。我们自第二年以来完成的工作如下，尽管我们研究的最新进展将包含在长达 60 页的论文集中，并附在“我们的研究结果报告”中： 硅藻 - Denticulopsis 是生物地层学上的一个重要属，包括几个难以归属的物种。这就需要通过生物识别为其分类奠定有效的基础。结果，与计数室一起测量了每个条带的长度和宽度。结果表明，对于D. lauta，大多数条带的室数为奇数，最多为3或5个；关于出现在带末端的顶端假隔膜的排列，存在三种类型；腔室数量和顶端假隔膜在分析其生命周期时更加重要；带的长度和室数之间呈正相关，这表明细胞分裂不仅会导致带长度的减少，而且会导致其结构的改变。介形类——更新世期间海平面波动引起的间接事件导致介形类物种的区域性灭绝，这可能涉及到生态限制，这似乎反映在它们的矮甲壳上，例如中华介形纲（Sinocytheridea latiovata）。

The purpose of this research is to appraise the morphological variation of microfossils, including foraminifers, ostracodes and diatoms, in time and space, as well as to clarify the vicissitudes of microfossils through Cenozoic time. In 1988, we installed an image processor recently improved, and then have been engaged in selecting parameters suitable for measuring and setting off the morphological variations of microfossils among and within species in each of the above groups. Among pieces of our work accomplished since the second year are the following, although recent progress in our research will be contained in the collected papers, running into 60 pages, annexed to "the report on the results of our research" : Diatoms- Denticulopsis, a biostratigraphically important genus, includes several species which are difficult to be assigned to one or the others. This calls for biometrically laying foundations valid for their classification. In consequence, the length and width were measured, together with counting chambers, of each of the bands. The results show that with respect to D. lauta, the majority of bands have odd numbers of chambers, with a maximum number of 3 or 5 ; the existence of three types as to the arrangement of apical pseudosepta appearing at the ends of a band ; greater importance of chamber numbers and apical pseudosepta in analyzing their life cycles ; positive correlations between the length of and chamber numbers on bands, which indicate the possibility that the cell division gives rise not only to a reduction in the length of bands, but also to the modifications of their structures. Ostracodes- The regional extinction of stracode species due to a vicariance event caused by sea level fluctuations during the Pleistocene might involve ecological constraints which seem to be reflected on their dwarf carapaces, as exemplified by Sinocytheridea latiovata.