Abstract

The morphology of acritarch species Elektoriskos? williereae (G. & M. Deflandre, 1965) Vanguestaine, 1979, previously considered as a Silurian index of the Llandovery, has been clarified, the diagnosis emended, and the stratigraphic distribution expanded. According to new data, the first appearance of E.? williereae was confined to the upper part of the Baksan Horizon near the boundary of the Sandbian and Katian stages of the Upper Ordovician. Co-occurrence of E.? williereae with representatives of the genera Gordonirundum, Nirundella, Peteinosphaeridium, and Sacculidium is a distinct, well-recognizable palynological characteristic of the Katian deposits of the Siberian Platform which can serve for identification, dating, and correlation of the acritarch-bearing strata. Morphological variations in E.? williereae are a stable diagnostic feature of the species that distinguishes it from other taxa. It is possible that the species was sensitive to paleoenvironments and, probably, highly adaptive, which allowed it, remaining almost unchanged, to overcome the global Late Ordovician cooling, which became fatal for many other groups of organisms.

中文翻译：

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Acritarch Elektoriskos？williereae (G. & M. Deflandre, 1965) Vanguestein, 1979 修正。十一月 来自西伯利亚平台的上奥陶统：新的形态和地层数据

摘要

acritarch 物种Elektoriskos 的形态？williereae (G. & M. Deflandre, 1965) Vanguestaine, 1979，以前被认为是 Llandovery 的志留纪指数，现已澄清，诊断修正，地层分布扩大。根据新数据，E.的首次出现。williereae被限制在上奥陶统的 Sandbian 和 Katian 阶段边界附近的 Baksan 地平线的上部。E.的共现？williereae与Gordonirundum、Nirundella、Peteinosphaeridium和Sacculidium属的代表是西伯利亚地台 Katian 矿床的一个独特的、公认的孢粉学特征，可用于识别、定年和对比含 acritarch 的地层。E.的形态变异？williereae是该物种的稳定诊断特征，可将其与其他分类群区分开来。该物种可能对古环境敏感，并且可能具有高度适应性，这使得它几乎保持不变，克服了全球晚奥陶世变冷，这对许多其他生物群体来说是致命的。