贵州关岭生物群中植物化石的发现及其意义

关岭生物群是近年来在我国贵州关岭地区瓦窑组中发现的一个十分重要的生物群 ,其中的植物化石经研究计有 Equisetites cf.arenaceus(Jaeger) Bronn.、Ctenozamitessarrani Zeiller。依据植物化石 C.sarrani常见于晚三叠世和 E.cf.arenaceus系似木贼属中较古老的类型 ,指出含植物化石的地层时代为晚三叠世卡尼期。瓦窑组系海相沉积 ,其中的植物化石无疑为异地埋藏 ,但从化石通常保存尚好来看 ,估计搬运的距离不会很远 ,它们可能是从距海岸不远的陆地被河流带到较平静的海湾或海槽而沉积下来的。此外 ,从该组植物茎干化石具清楚的年轮分析 ,推测卡尼期时 ,贵州关岭一带为非热带雨林地区 ,一年中气候不是四季如一 ,而是有明显的季节变化

DISCOVERY OF FOSSIL PLANTS FROM GUANLING BIOTA IN GUIZHOU AND ITS SIGNIFICANCES

The Guanling Biota is very important and was found in the Wayao Formation of the Guanling area, Guizhou in the latest years. This biota is characterized by the incoming of a great deal of well preserved marine reptiles, crinoids, together with ammonoids, conodonts and a small number of fishes and brachiopods. Study of associated fossil plants recently found in the Guanling Biota indicates that the main elements are Equisetites cf. arenaceus (Jaeger) Bronn. and Ctenozamites sarrani Zeiller. These fossil plants are usually present in the Late Triassic and Equisetites cf. arenaceus is an older form of the genus, so that it is suggested that the rocks bearing these plants in the Wayao Formatin be of Carnian age. The Wayao Formation is composed of a sequence of marine deposit. These well preserved fossil plants undoubtedly belong to allochthonous tapocoenose group transported from the place not far away. They migh be carried to the calm bay or sea channel from the nearest land or seacoast by the flowing water. In addition, analysis of these distinct annual rings existing on the transversal section of some fossil plant stem, indicates that the Guanling and its adjicent areas would belong to non tropical rain forest zone during the Carnian and the climate there was obvious seasons in each year, not as warm as the spring all the year round.