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Интеллектуальная Система Тематического Исследования НАукометрических данных |
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Preliminary report on a new sphenophyllaceous cone from the Lower Famennian of Kazakhstanтезисы доклада
- Авторы: Jurina A., Orlova O.A., Mamontov D.A.
- Сборник: Terra Nostra. 2008/2, IPC-XII /IOPC-VIII Bonn, Germany
- Том: 2
- Тезисы
- Год издания: 2008
- Место издания: Bonn
- Первая страница: 135
- Последняя страница: 136
- Аннотация: New sphenophyllaceous cone has been studied from the Famennian deposits of southwestern part of the Central Kazakhstan. Besides the cone a number of the Late Devonian plants: Leptophloeum rhombicum Dawson, and Barinostrobus otjericus Jurina also occur in this locality. The layer inclosing the flora was covered by the beds of the standard conodontal zones: crepida-rhomboidea of the Lower Famennian (Ziegler, Sandberg, 1990). The cone is preserved as impression. The cone is not compact, with loose whorls. The axis of the cone is articulate, up to 40 mm long, and 1,08-1,00 mm wide. It has 12-13 internodes up to 2,4-2,8 mm long. Apparently there were six whorled sporangiophores at each node of axis. Each sporangiophore is laminated in outline. It consists of a lower horizontal portion and upper upward one, which coiled distally to the axis and dichotomously branched at the end into two short parts. They are terminated by a single inverted globular sporangium up to 1,1-1,2 mm wide and 1,1 mm high. The two sporangia are overlapped each other. There are two Late Devonian genera (Eviostachya Stockmans, 1948, and Pseudobornia Nathorst, 1894), which are relate to sphenophyllalean. The cone of Eviostachya (Belgium, Upper Famennian) consists of a central axis with the whorls of fertile sporangiophores. Each sporangiophore of Eviostachya trifurcates twice. All sporangiophores are terminated with numerous pendant sporangia. The cone of Eviostachya is similar to cone studied only in absence of whorls of bracts between the sporangiophores. Another Late Devonian genus – Pseudobornia (Norway, Upper Famennian) is represented by spike consisting of closely spaced alternating whorls of bracts and sporangiophores. The latter was forked, upturned with numerous sporangia on each sporangiophore. The comparison of the spike of Pseudobornia with the cone under study is impossible because of absence of the common features. The new cone from Kazakhstan is most similar to the Carboniferous cone of Bowmanites Binney, 1871, in particular, to section Simplices (according to Hoskins, Cross, 1943). It is characterised by one or two (in pairs) sporangia (often in an anatropous fashion). Besides sporangiophores of Simplices are often not arranged in compact cones. We consider the Late Famennian cone from Kazakhstan to be one of the most simply organised members of sphenophyllaceous fructifications and the earliest one in geological history.
- Добавил в систему: Орлова Ольга Александровна