New Observations and Synthesis of Paleogene Heterosporous Water Ferns
New Observations and Synthesis of Paleogene Heterosporous Water Ferns
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古近纪异孢水蕨的新观察与合成
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
F. Marone
中科院分区：
文献类型：
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作者：
M. Collinson;Selena Y. Smith;Johanna H. A. van Konijnenburg;D. Batten;J. van der Burgh;J. Barke;F. Marone
研究的前提：现代异孢水生蕨类植物属（马茜科和Salviniaceae）的生殖结构在古近纪植物中化石组合中广泛而丰富。 对于Salviniaceae，完整的可育化石植物提供了很好的形态学理解。这些化石可用于古环境分析，并研究水蕨的起源，进化和多样化。方法学：用扫描电镜和透射电镜检查新标本。 同步辐射X射线层析显微镜（SRXTM）的评价作为一种非破坏性的工具，调查满江红林。形态学初步结果：利用扫描电镜和透射电镜对英国始新世最早的满江红（Azolla anglica Martin）和科氏槐叶萍（Salvinia cobhamii Martin）进行了全面的表征。 SRXTM可以对Azolla中的浮子系统进行数字渲染，但很难区分单个浮子。现代的水蕨属是古近纪的特征，但灭绝的姐妹类群是白垩纪的特征。文献回顾表明，水蕨不能耐受超过5 psu的盐度。结论：有充分记载的最古老的Salvinia Séguier囊群和孢子出现在英国科巴姆始新世最早期的沉积物中，可能与温暖的气候有关。 一个不寻常的共生的槐叶萍与满江红是保存在这个网站。红萍物种不同于那些在同一地区的其他始新世温暖的气候间隔。SRXTM提供了潜在的检索分类学上有用的信息满江红的内部结构。有一个主要的营业额在水蕨类植物（占主导地位的灭绝，几乎完全现代属）跨越古近纪-古近纪过渡。水蕨类植物作为指示类群的实用性的例子是承认淡水海洋表面和广泛的大陆湿地在最新的早至最早的中始新世在北极和北欧海及其周围。
Premise of research. Reproductive structures of modern genera of heterosporous water ferns (Marsileaceae and Salviniaceae) are widespread and abundant in plant mesofossil assemblages from the Paleogene. For Salviniaceae, whole fertile fossil plants give a good understanding of morphology. These fossils can be applied in paleoenvironmental analysis and to study water fern origin, evolution, and diversification. Methodology. New specimens were examined by SEM and TEM. Synchrotron x-ray tomographic microscopy (SRXTM) is evaluated as a nondestructive tool for investigating Azolla Lam. morphology. Pivotal results. Azolla anglica Martin and Salvinia cobhamii Martin (earliest Eocene, United Kingdom) are fully characterized using SEM and TEM. SRXTM enables digital rendering of the float system in Azolla, but individual floats are difficult to distinguish. Modern water fern genera characterize the Paleogene, but extinct sister taxa characterize the Cretaceous. Literature review documents that water ferns are intolerant of salinity over 5 psu. Conclusions. The oldest fully documented Salvinia Séguier sori and spores occur in earliest Eocene deposits at Cobham, United Kingdom, probably linked to warm climates. An unusual co-occurrence of Salvinia with Azolla is preserved at this site. The Azolla species differs from those present in the same region during other Eocene warm-climate intervals. SRXTM offers potential to retrieve taxonomically useful information on internal structures of Azolla. There is a major turnover in water ferns (dominantly extinct to almost entirely modern genera) across the Cretaceous-Paleogene transition. The utility of water ferns as indicator taxa is exemplified by recognition of freshwater ocean surfaces and widespread continental wetlands during the latest Early to earliest Middle Eocene in and around the Arctic and Nordic Seas.