Abstract

This study provides a description of the Devonian radiolarian associations of northern Eurasia and discusses their role in the evolution of Earth’s biosphere. It contributes to evolutionary studies of the Earth and its organic world by reconstructing the diversity dynamics of the Devonian radiolarian biota and the chorology of its components, at the same time revealing the biostratigraphic and paleoecological potential of radiolarians. The taxonomic composition and characteristics of the dominant morphotypes in radiolarian communities are indicators of environmental conditions. Associations of radiolarians vary significantly between different, even neighboring, water areas, so they can be considered as ecozones. Data on the structure of associations of radiolarians at the level of taxa of higher rank (classes) are a kind of “certificate” or “passport” of ecozones of individual paleobasins. Radiolarian ecozones replace each other in time, which allows their use for biostratigraphy. The results of the new and revisional studies of the Devonian radiolarians from 15 regions of northern Eurasia enabled a refined and detailed radiolarian scale of the Devonian system and description of 39 Devonian radiolarian ecozones, 24 of which are described for the first time: 17 ecozones are recognized based on the literature data, while seven ecozones are based on analysis of new data. Of 39 ecozones, 33 are dated based on conodont data, and six are dated using the co-occurring foraminifers, ostracodes, and/or ammonoids. General patterns in the evolution of Devonian radiolarians of northern Eurasia are considered and discussed. Spherical porous Sphaerellaria distinctly dominated in the Devonian. A clear trend towards an eastward increase in the relative abundance of spongy and latticed morphotypes of Spumellaria is shown. Spiny Aculearia of the orders Fasciculata and Triangulata are found to have been widespread. The early evolution of the bilaterally symmetrical Albaillellata is recorded. It is shown that in the Famennian, radiolarians with a pylome, Popofskyellidae and Archocyrtiinae, were common, while the genus Caspiaza first appeared at that time. The habitats and the distribution of the discoidal and ellipsoidal radiolarian morphotypes are analyzed in space and time. The dominance of these morphotypes can be used as an indicator of shallow water settings and a marker of transgression and regression boundaries in the paleobasin. A model of cyclic deposition of Domanik-type rocks in an anoxic basin is proposed, and the ecology of radiolarians in the anoxic environments of the Middle Frasnian Domanik Paleosea is analyzed. The predominance of the spiny morphotypes over spherical radiolarians is proposed as a paleoclimatic coefficient indicating cooling of the seawater in a paleobasin. Devonian radiolarians are represented by indigenous species and migrant species: (1) the value of the settled index exceeds that of the migration index by 3–5 times, (2) radiolarians occupied new ecological niches by emigration of evolutionarily young species representing genera with one–two species in total. Four radiolarian migration episodes are established in the Famennian basins of Laurussia. The monograph is intended for widespread use in paleontology, biostratigraphy, paleoecology, paleobiogeography and for university courses.

中文翻译：

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欧亚大陆的泥盆纪放射虫生态区

摘要

这项研究描述了北欧亚大陆的泥盆纪放射虫协会，并讨论了它们在地球生物圈演化中的作用。它通过重建泥盆纪放射虫生物群的多样性动力学及其组成的学说，为地球及其有机世界的进化研究做出了贡献，同时揭示了放射虫的生物地层学和古生态潜力。放射虫群落中主要形态型的分类学组成和特征是环境状况的指标。在不同甚至邻近的水域之间，放射虫的关联差异很大，因此可以将其视为生态区。在较高等级（类别）的分类单元级别上，放射虫协会的结构数据是单个古生物的生态区的“证明”或“护照”。放射虫生态区会及时相互替换，从而可以用于生物地层学。来自欧亚大陆北部15个地区的泥盆纪放射虫的最新研究和修订研究的结果，使泥盆纪系统的放射虫规模更加精细和详尽，并描述了39个泥盆纪放射虫生态区，其中首次描述了24个：根据文献数据进行识别，而七个生态区则基于对新数据的分析。在39个生态区中，有33个是根据牙形石数据确定日期的，而6个是使用同时出现的有孔虫，ostracodes和/或ammonoids确定的。考虑和讨论了北欧亚大陆泥盆纪放射虫演化的一般模式。泥盆纪的球形疏松球菌明显占优势。显示了明显的趋势，即Spumellaria的海绵状和格子状形态的相对丰度向东增加。Fasciculata和Triangulata目的刺棘鱼被广泛发现。记录了双边对称的信天翁的早期演变。结果表明，在法门尼人中，带有幽门的放射虫，Popofskyellidae和Archocyrtiinae是常见的，而属 显示了明显的趋势，即Spumellaria的海绵状和格子状形态的相对丰度向东增加。Fasciculata和Triangulata目的棘刺棘被发现很普遍。记录了双边对称的信天翁的早期演变。结果表明，在法门尼人中，带有幽门的放射虫，Popofskyellidae和Archocyrtiinae是常见的，而属 显示了明显的趋势，即Spumellaria的海绵状和格子状形态的相对丰度向东增加。Fasciculata和Triangulata目的棘刺棘被发现很普遍。记录了双边对称的信天翁的早期演变。结果表明，在法门尼人中，带有幽门的放射虫，Popofskyellidae和Archocyrtiinae是常见的，而属卡皮亚萨最早出现在那个时候。分析了盘状和椭圆形放射虫形态的生境和分布。这些形态型的优势可以用作浅水环境的指标，以及古巴辛中海侵和回归边界的标志。提出了缺氧盆地中Domanik型岩石的周期性沉积模型，并分析了中弗拉西尼亚Domanik古海洋缺氧环境中放射虫的生态。有人提出在球形放射虫上多刺的形态型被认为是古气候系数，表明海水在古巴辛中是冷却的。泥盆纪放射虫以土著物种和迁徙物种为代表：（1）定居指数的价值超过迁徙指数的3-5倍，（2）放射虫通过迁徙代表一属的进化上年轻的物种共占据一两个物种而占据了新的生态位。在月桂的法门尼亚盆地中建立了四个放射虫迁移事件。该专着旨在广泛用于古生物学，生物地层学，古生态学，古生物地理学和大学课程。