| 中国东北首次发现白垩纪紫萁科叶柄基化石 |
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| 引用本文：程业明,刘风香,靳悦高.2019.中国东北首次发现白垩纪紫萁科叶柄基化石[J].地球学报,40(5):699-707. |
| DOI：10.3975/cagsb.2019.012901 |
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| 基金项目:东北亚生物演化与环境教育部重点实验室(编号: 2018JDEPw001);自然资源部部门预算项目(编号: 121113000000160404) |
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| 中文摘要:我国东北地区是北半球少有的中生代紫萁科茎干化石产地之一。该地区出产的茎干化石为研究中生代紫萁科的演化历史提供了重要证据。我国过去报道的紫萁科茎干化石来自东北地区的侏罗系。近期在东北松辽盆地北部白垩系发现了紫萁科茎干化石, 为认识紫萁科在中生代晚期的演化发展过程提供了不可或缺的证据。本研究报道了在黑龙江省五大连池市和平镇发现的白垩纪紫萁科叶柄基化石。横切面上看叶柄基以茎缺失的位置为中心螺旋状排列, 较为紧密。维管束木质部呈深凹的C形, 末端向内弯曲。维管束凹陷处有薄的C形、边缘呈波纹状的厚壁组织带。C形维管束与厚壁组织带之间分布着薄壁细胞组成的粘液囊。内皮层中分布着不规则排列的若干厚壁组织束。近轴端叶柄基托叶翼中分布有2个较大和若干小的厚壁组织束; 大的厚壁组织束呈水滴形。随着叶柄基由近轴端向远轴端的延伸, 维管束近轴面凹陷处的厚壁组织带长度增长, 粘液囊数量增加; 托叶翼中厚壁组织束数量相应增加, 除了两个大的厚壁组织束外, 它们附近增加了若干大小不等的厚壁组织束和单个厚壁纤维细胞。当前化石是我国第一个白垩纪保存解剖结构的紫萁科化石记录。其结构特征与灭绝的Osmundacaulis和现存的Plenasium的叶柄基比较相似, 可能代表了白垩纪以上两属的成员之一。由于目前欧亚大陆白垩纪还未见Osmundacaulis和Plenasium的茎干化石记录, 当前化石的发现丰富了欧亚大陆白垩纪紫萁科植物的多样性。 |
| 中文关键词:紫萁科 叶柄基 解剖结构 粘液囊 松辽盆地 白垩系 |
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| The First Discovery of a Cretaceous Petiole Base of Osmundaceae from Northeast China |
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| Abstract:Northeast China is one of the rare localities of the Mesozoic Osmundaceae axes in the Northern Hemisphere. The fossils provide important evidence for the study of the evolution of the family Osmundaceae. The rhizome fossils of Osmundaceae found in China have been reported only from the Jurassic sediments. The Cretaceous trunk or rhizome of Osmundaceae were recently found in the Songliao Basin, Northeast China, which provides an indispensable evidence for understanding the evolution of the family Osmundaceae in Late Mesozoic. In this study, the authors reported the petiole base fossil of Osmundaceae from Heping Town, Wudalianchi City, Heilongjiang Province. In a transverse section, the petiole bases are spirally arranged, and quite close to each other. For the internal structure, the vascular bundle of the petiole base is in deeply-concaved C-shape, with its end bent inward. There are C-shaped and lobed sclerenchyma bands at the concavity of the vascular bundle. Between the vascular bundle and the C-shaped sclerenchyma bands, there are several mucilage sacs. In the inner cortex of the petiole base, there are several irregularly arranged sclerenchyma strands, especially on the adaxial side of the C-shaped sclerenchyma strands. There are 2 big sclerenchyma strands (in the shape of water drop) and several small strands in the stipule wing of the proximal petiole base. With the extension of petiole base from proximal to the distal end, the length of sclerenchyma bands and the number of mucilage sacs increase. At the high level of the petiole base, there are various sizes of sclerenchyma strands, and many single thick-walled fibers in addition to the 2 big sclerenchyma strands. The present fossil is the first structurally preserved Osmundaceae petiole base in the Cretaceous of China. The structural characteristics of the present fossil is similar to those of the petiole bases of extinct Osmundacaulis and the extant Plenasium. It could be a member of Plenasium or Osmundacaulis. At present, no fossil rhizome or trunk records of Plenasium and Osmundacaulis have been found in the Cretaceous of Eurasia. The present fossils have enriched the diversity of the Cretaceous Osmundaceae in Eurasia. |
| keywords:Osmundaceae petiole base anatomy mucilage sacs Songliao Basin Cretaceous |
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