【作者】 张英芳；

【导师】 孙克勤；

【作者基本信息】 中国地质大学（北京） ， 古生物学与地层学， 2006， 硕士

【摘要】 本文研究的化石产在北京西部九龙山南坡的窑坡组和龙门组。室内鉴定和描述化石22属38种,分别属于楔叶纲、真蕨纲、苏铁纲、银杏纲和松柏纲植物。经植物种类分析,标准植物分子分析,与标准植物群对比分析三方面判定为中侏罗世植物化石。根据化石保存状态,化石大小和化石保存的完整程度,分析化石主要为原地埋藏,所以植物化石特征能够反映当地的生态环境。根据现生各类植物的生存环境,恢复了北京西山中侏罗世植物的生态环境,并划分了三个植物群落:岸边低地-沼泽Equisetum laterale-Equisetum beani群落;平原低地Cladophlebisasiataca-Coniopteris beijingsis群落;平地或高地缓坡Elatocladusmanchurica-Podozamites lanceolatus群落。本文采用植物的现生近缘种类分析和叶相分析的多种定量分析方法,并结合其它方面的证据,着重研究北京西山中侏罗世的气候特征。经研究得知,植物群中喜湿热的真蕨纲植物(31.6%)和苏铁纲植物(23.7%)的比重大,全缘叶比例为51.6%,年均温16.9℃,多方面的数据表明当时气候湿热,为亚热带气候。并且,随时间的变化,气候逐渐变得干热。经对比分析,作者研究的植物群与陈芬、窦亚伟、黄其胜(1984)研究的门头沟植物群和段淑英(1987)研究的斋堂植物群同为北京西山中侏罗世植物群的组成部分。本文引进和运用分支生物地理学的方法进行植物地理分区研究。把北京西山中侏罗世植物群与同期的辽西植物群、柴达木北缘植物群、英国约克郡植物群、西伯利亚区的植物群详细对比,分析植物群的近缘关系来判断植物地理区。结果表明,北京西山植物群和辽西植物群关系比与柴达木北缘植物群亲近。北京西山中侏罗世植物群位于西伯利亚植物区和欧洲-中国植物区的分界线附近,把其划归到欧洲-中国植物分区,即和我国南方植物群同属一个植物地理分区是合理的。更多还原

【Abstract】 The plant fossils discussed in this paper was collected from the Yaopo and Longmenformations of southern Jiulongshan in Western Hills of Beijing. There are 38 species in 22genera. These species are in different groups which comprise Sphenopsida, Filicopsida,Cycadopsida, Coniferopsida and Ginkgopsida. The flora may be designated as MiddleJurassic in age. The taphonomic types of the fossil plants are analyzed according to theirstates of preservation, sizes and characters. It is sure that most of them are autochthonousburial. So the flora characters could reflect paleoecological environment. The fossil plantsare divided into three plant assemblages, namely, Equisetum laterale-Equisetum beaniassemblage, Cladophlebis asiataca-Coniopteris beijingsis assemblage and Elatocladusmanchurica-Podozamites lanceolatus assemblage. In this essay, emphasis is laid on thestudy of climate reconstruction. There are two main approaches used in this paper, whichare Nearest-Living-Relatives-Method and Leaf-Physiognomy-Analysis. Results of thestudy show that the dominant groups are Filicopsida (31.6%) and Cycadopsida (23.7%),the proportion of entire margined species is 51.6%, mean annual temperature is 16.9℃.The flora indicates a humid-warm close to subtropical climate and also indicates awarming and drying climatic change in Middle Jurassic.The Middle Jurassic flora in Western Hills of Beijing also includes Mentougou florain Chenfen, Douyawei, Huangqisheng (1984) and Zhaitang flora in Duanshuying (1987)by comparison. Cladistic biogeography is used to interpret pattern of plant distribution.The Middle Jurassic flora in Western Hills of Beijing is compared with contemporaryfloras, such as, floras of western Liaoning, northern Chaidamu, Siberian and Yorkshire.The relatives of each flora are analyzed to conclude phytogeography. The result showsthat flora of western Liaoning is closer to flora in Western Hills of Beijing than to flora ofnorthern Chaidamu. The flora of Middle Jurassic in Western Hills of Beijing is near theboundary between the Siberian and Euro-Sinian phytogeographic regions. It is reasonablethat the flora of Middle Jurassic in Western Hills of Beijing is in Euro-Sinian phytochorialregion, just as the Southern floras of China.更多还原