A specialized new species of Ashicaulis (Osmundaceae,Filicales) from the Jurassic of Liaoning,NE China |
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Authors: | Ning Tian Yong-Dong Wang Marc Philippe Wu Zhang Zi-Kun Jiang Li-Qin Li |
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Institution: | 1. College of Palaeontology, Shenyang Normal University, Shenyang, 110034, China 2. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, CAS, Nanjing, 210008, China 3. Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, 210008, China 4. Laboratoire de Géologie de Lyon, Université Claude Bernard Lyon 1, Campus de la DOUA, Batiment, Dubois/Darwin A, 69622, Villeurbanne Cedex, France 5. Shenyang Institute of Geology and Mineral Resources, Ministry of Land and Resources, Shenyang, 110034, China 6. Chinese Academy of Geological Sciences, Beijing, 100037, China
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Abstract: | A new species of structurally preserved fern rhizome, Ashicaulis plumites (Osmundaceae, Filicales), is described from the Middle Jurassic Tiaojishan Formation in western Liaoning Province, NE China. The new species is characterized by a peculiar sclerenchyma mass in the petiolar vascular bundle concavity. This sclerenchyma mass varies from a linear-shape to a mushroom-like shape with a remarkable outward protuberance, which distinguishes the present new species from other Ashicaulis species. Such a protuberance is very rare among osmundaceous ferns, and should represent a unique type for sclerenchymatous tissue in the osmundaceous vascular bundle concavity. Recognition of the peculiar structure of this new fossil species enriches anatomical diversity of permineralized osmundaceous ferns, indicating that the family Osmundaceae might have experienced a remarkable diversification during the Middle Jurassic in NE China. The new species show anatomical similarities to Osmunda pluma Miller from the Palaeocene of North America. The occurrence of A. plumites in the Middle Jurassic of China provides a new clue for understanding the evolution of some members of the living subgenus Osmunda. |
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