| 中国东北首次发现白垩纪紫萁科叶柄基化石 |
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| 关键词:Osmundaceae petiole base anatomy mucilage sacs Songliao Basin Cretaceous |
| 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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| The First Discovery of a Cretaceous Petiole Base of Osmundaceae from Northeast China |
| 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. |
| CHENG Ye-ming,LIU Feng-xiang,JIN Yue-gao.2019.The First Discovery of a Cretaceous Petiole Base of Osmundaceae from Northeast China[J].Acta Geoscientica Sinica,40(5):699-707. |
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