Talyzina NM, Moczydowska M
Uppsala University, Department of Earth Sciences, Historical Geology and Palaeontology, Norbyvägen 22, 75236, Uppsala, Sweden
Rev Palaeobot Palynol. 2000 Oct 1;112(1-3):1-21. doi: 10.1016/s0034-6667(00)00032-4.
Six acritarch species from the Lükati Formation were studied using a combination of techniques, including transmitted light, scanning electron (SEM) and transmission electron (TEM) microscopy. New details of wall ultrastructure, surface microsculpture and internal morphology of the vesicle and processes significantly add to the previously known morphological features and increase the understanding of the form-genera Archaeodiscina, Globosphaeridium, Comasphaeridium, Skiagia, Tasmanites and Leiosphaeridia. Examination of microfossils using TEM revealed a substantial variation in wall ultrastructure among acritarchs. The diversity includes four structural types of vesicle wall in addition to their single- and multi-layered structure and the variable thickness of the wall. These are: electron-tenuous and fibrous; electron-dense and homogeneous; electron-dense and homogeneous but perforated by radial canals; and composite laminated structure. Morphologically recognised groupings of acritarchs (acanthomorphic, disphaeromorphic, sphaeromorphic) and tasmanitid taxa appear to be characterised by particular features of the wall structure, although the wall structure in itself may not be directly indicative of systematic relationships. Structurally diverse vesicle walls are observed in Tasmanites and Leiosphaeridia, taxa that both have been interpreted, based on other lines of evidence, to be of prasinophycean (green algal) affinities. The distinct wall ultrastructure of the Leiosphaeridia studied is similar to that of extant green algal genera, which provides evidence that some Cambrian leiosphaerids were chlorophycean algae, probably related to the Order Chlorococcales. Previous research and interpretations of the wall ultrastructure are also briefly discussed.
利用透射光、扫描电子显微镜（SEM）和透射电子显微镜（TEM）等多种技术，对卢卡蒂组的六种疑源类物种进行了研究。囊泡壁超微结构、表面微雕以及囊泡和突起的内部形态的新细节显著增加了先前已知的形态特征，并增进了对形态属古盘藻属、球囊藻属、彗星藻属、斯基藻属、塔斯曼藻属和光面球藻属的了解。使用透射电子显微镜对微化石的研究揭示了疑源类之间壁超微结构的显著差异。这种多样性包括囊泡壁的四种结构类型，此外还有它们的单层和多层结构以及壁的可变厚度。这些类型分别是：电子稀疏且呈纤维状；电子致密且均匀；电子致密且均匀但有放射状管道穿孔；以及复合层状结构。从形态上识别的疑源类分组（棘刺状、双球型、球型）和塔斯曼藻类群似乎具有壁结构的特定特征，尽管壁结构本身可能并不直接指示系统发育关系。在塔斯曼藻属和光面球藻属中观察到结构多样的囊泡壁，根据其他证据线索，这两个类群都被解释为具有绿藻门（绿藻）的亲缘关系。所研究的光面球藻独特的壁超微结构与现存绿藻属的相似，这为一些寒武纪光面球藻是绿藻门藻类提供了证据，可能与绿球藻目有关。还简要讨论了先前对壁超微结构的研究和解释。
