Department of Earth and Space Sciences, University of California, Geology Building, Los Angeles, California 90095-1567, USA.
Am J Bot. 2013 Aug;100(8):1626-40. doi: 10.3732/ajb.1300027. Epub 2013 Aug 7.
Permineralization provides the most faithful known mode of three-dimensional preservation of the morphology and cellular anatomy of fossil plants. Standard optical microscopic documentation of such structures can provide only an approximation of their true three-dimensional form and is incapable of revealing fine-structural (<300 nm) details, deficiencies that can be addressed by the use of confocal laser scanning microscopy (CLSM).
To demonstrate the usefulness of CLSM in such studies, we compare confocal laser scanning micrographs and optical photomicrographs of the permineralized tissues of rhizomes and petioles of the Eocene fern Dennstaedtiopsis aerenchymata preserved in cherts of the Clarno Formation of Oregon, USA, and the Allenby Formation (Princeton chert) of British Columbia, Canada.
The laser-induced fluorescence detected by CLSM produces crisp high-resolution images of the three-dimensionally permineralized tissues of Dennstaedtiopsis aerenchymata. Tissues analyzed include the epidermis and epidermal hairs, cortex, aerenchyma, endodermis, vascular tissue, and pith-for each of which, CLSM yields results superior to those of standard optical microscopy. CLSM and previous Raman spectroscopic analyses of the same specimens provide evidence consistent with original biochemistry.
Use of CLSM to characterize the morphology and cellular anatomy of permineralized fossil plants can provide accurate data in two and three dimensions at high spatial resolution, information that can be critically important to taxonomic, taphonomic, and developmental interpretations. Results presented here from this first detailed CLSM-based study of permineralized plant axes indicate that this nonintrusive, nondestructive technique should be widely applicable in paleobotany.
矿化作用提供了最忠实的三维保存化石植物形态和细胞解剖结构的已知模式。对这些结构进行标准光学显微镜记录只能近似地反映其真实的三维形态，并且无法揭示细微结构（<300nm）的细节，这些缺陷可以通过使用共聚焦激光扫描显微镜（CLSM）来解决。
为了证明 CLSM 在这些研究中的有用性，我们比较了美国俄勒冈州克拉诺组燧石和加拿大不列颠哥伦比亚省艾伦比组（普林斯顿燧石）保存的始蕨目 Dennstaedtiopsis aerenchymata 根茎和叶柄的矿化组织的共聚焦激光扫描显微镜和光学显微镜照片。
CLSM 检测到的激光诱导荧光产生了始蕨目 Dennstaedtiopsis aerenchymata 的三维矿化组织的清晰高分辨率图像。分析的组织包括表皮和表皮毛、皮层、通气组织、内皮层、维管束和髓心——对于每一种组织，CLSM 的结果都优于标准光学显微镜。CLSM 和对同一标本的先前拉曼光谱分析提供的证据与原始生物化学一致。
使用 CLSM 来描述矿化化石植物的形态和细胞解剖结构，可以在高空间分辨率下以二维和三维形式提供准确的数据，这些信息对于分类学、埋藏学和发育解释可能至关重要。本文首次对矿化植物轴进行基于 CLSM 的详细研究的结果表明，这种非侵入性、非破坏性技术应该在古植物学中得到广泛应用。
