Moreau Jean-David, Néraudeau Didier, Tafforeau Paul, Dépré Éric
CNRS UMR 6118, Géosciences Rennes, Université Rennes 1, Rennes, France; Beamline ID19, European Synchrotron Radiation Facility, Grenoble, France.
CNRS UMR 6118, Géosciences Rennes, Université Rennes 1, Rennes, France.
PLoS One. 2015 Aug 19;10(8):e0134515. doi: 10.1371/journal.pone.0134515. eCollection 2015.
We report exceptionally well-preserved plant remains ascribed to the extinct conifer Glenrosa J. Watson et H.L. Fisher emend. V. Srinivasan inside silica-rich nodules from the Cenomanian of the Font-de-Benon quarry, Charente-Maritime, western France. Remains are preserved in three dimensions and mainly consist of fragmented leafy axes. Pollen cones of this conifer are for the first time reported and in some cases remain connected to leafy stems. Histology of Glenrosa has not previously been observed; here, most of internal tissues and cells are well-preserved and allow us to describe a new species, Glenrosa carentonensis sp. nov., using propagation phase-contrast X-ray synchrotron microtomography, a non-destructive technique. Leafy axes consist of characteristic helically arranged leaves bearing stomatal crypts. Glenrosa carentonensis sp. nov. differs from the other described species in developing a phyllotaxy 8/21, claw-shaped leaves, a thicker cuticle, a higher number of papillae and stomata per crypt. Pollen cones consist of peltate, helically arranged microsporophylls, each of them bearing 6-7 pollen sacs. The new high resolution tomographic approach tested here allows virtual palaeohistology on plants included inside a dense rock to be made. Most tissues of Glenrosa carentonensis sp. nov. are described. Lithological and palaeontological data combined with xerophytic features of Glenrosa carentonensis sp. nov. suggest that this conifer has been adapted to survive in harsh and instable environments such as coastal area exposed to hot, dry conditions.
我们报道了来自法国西部滨海夏朗德省丰德贝农采石场森诺曼阶富含硅质结核内保存异常完好的植物遗骸，这些遗骸归属于已灭绝的针叶树格伦罗莎（Glenrosa J. Watson et H.L. Fisher emend. V. Srinivasan）。遗骸呈三维保存，主要由破碎的叶轴组成。首次报道了这种针叶树的花粉球果，在某些情况下，花粉球果仍与叶茎相连。此前尚未观察到格伦罗莎的组织学特征；在此，大部分内部组织和细胞保存完好，使我们能够利用传播相衬X射线同步加速器显微断层扫描技术（一种无损技术）描述一个新物种——卡伦通格伦罗莎（Glenrosa carentonensis sp. nov.）。叶轴由带有气孔窝的特征性螺旋排列的叶子组成。卡伦通格伦罗莎新物种与其他已描述物种的不同之处在于其叶序为8/21、叶子呈爪形、角质层更厚、每个窝内的乳头和气孔数量更多。花粉球果由盾形、螺旋排列的小孢子叶组成，每个小孢子叶带有6 - 7个花粉囊。这里测试的新的高分辨率断层扫描方法使得对致密岩石内包含的植物进行虚拟古组织学研究成为可能。描述了卡伦通格伦罗莎新物种的大部分组织。岩石学和古生物学数据与卡伦通格伦罗莎新物种的旱生特征相结合，表明这种针叶树已适应在恶劣和不稳定的环境中生存，如暴露于炎热、干燥条件下的沿海地区。
