Phylogenetic relationship between Miocene permineralized plants and modern species.

日本北海道中北部的下川群中中新世莫山如组含有保存完好的硅化植物遗迹，显示出精细的组织结构。本文对莫山如组Shimokawa岩中硅化植物的形态解剖进行了阐述，为菊科植物的系统发育重建提供了资料。在此基础上，对毛山如组的地质、植物区系和植被进行了古环境背景研究。根据岩性和沉积特征，该组代表了几种沉积环境：陆相沉积、河道沉积、洪泛平原（森林化石遗迹）和湖相沉积。该组上部有7个硅化层（S1-S7），保存完好的植物部分大部分来自S3层。该组合主要由针叶和阔叶元素组成，其中包括两个现已灭绝的分类群。更多的分类群可能生长在潮湿的温带环境中：蕨类；针叶树属；冷杉属、云杉属、杉木属、山竹属和被子植物属；Decodon和Alnus。保存的质量是精美的，有几个遗迹可以进行精确的分类学研究。现有的化石和现存物种的解剖特征对系统发育关系进行了最重要的数据分析。营养器官和生殖器官解剖结构的详细资料为系统发育提供了资料。即使上述分类群的生殖结构未知，也可以从它们的营养结构中得到系统发育的结果。由于Osmunda分布广泛，在根状茎中具有许多特征，因此使用化石和现代物种可以更好地了解其系统发育。结果表明，在三叠纪发现了与肉桂属形态基本一致的化石种，因此肉桂属是肉桂科中定位最基础的种。在解剖结构上，肉桂黄貂鱼和克莱顿黄貂鱼有较大的差异。他们可能属于生物分化的群体。少

The Middle Miocene Mosanru Formation of the Shimokawa Group in north-central Hokkaido, Japan, contains well-preserved silicified plant remains showing fine and histological structure. This paper elucidates the morphological anatomy of silicified plants found in the Shimokawa chert of the Mosanru Formation and provides the data for phylogenetic reconstruction of Osmundaceae. Furthermore, geology, flora and vegetation of the Mosanru Formation has been investigated for paleoenvironmental context.Based on lithologic and sedimentary features, this Formation is interpreted to represent some environments of deposition : terrestrial sediments, fluvial channel, flood plain (remains of fossil forests), and lacustrine sediments. The upper part of this Formation has seven silicified beds (S1-S7) and nearly in situ well-preserved plant parts are mostly obtained from the S3 bed.The assemblage is composed mainly of coniferous and broad-leaved elements that include with two now-extinct taxa. Most of t … More he taxa probably grew in a swampy temperate environment : the fern genus ; Osmunda, the conifer genera ; Abies, Picea, Tsuga and Glyptostrobus, and the angiosperm genera ; Decodon and Alnus.The quality of preservation is exquisite, and several remains allow precise study of taxonomy. Available anatomical characters of both fossil and extant species were conducted to most significant data for phylogenetic relationship. The detailed data on anatomical structure of both vegetative and reproductive organs provides the data for phylogeny. Even when the reproductive structure of above mentioned taxa is unknown, the phylogenetic results can be gained from their vegetative structures.Since Osmunda were widely distributed and possess several characteristic features in the rhizomes, their phylogeny are better understood using both fossil and modern spccies. As the result, Osmunda cinnamomea is the most basally positioned species in Osmundaceae because fossil species with almost the same morphology as this species were recorded from the Triassic. Greater anatomical variation was found between Osmunda cinnamomea and O.claytoniana. They possibly belong to biologically differentiated groups. Less