中文摘要：

简要论述贵州凤冈志留纪Llandovery世晚期Pinnatiramosus qianensis Geng（黔羽枝）的研究历史、地层时代、主要特征、早期陆生维管植物起源和演化意义、争议焦点及其今后的研究途径和展望。P.qianensis代表了一类目前仍鲜为人知、由水生藻类植物向陆生环境过渡的植物类群,具有陆生维管植物某些重要特征,在后续演化过程中,可能是一类不成功的灭绝类群。由于P.qianensis的特有外部形态和复杂的内部解剖特征,对其认识引发了很大的争议,焦点集中在是否属于真正的志留纪植物（产出地层是否为志留纪Llandovery世晚期,是否属于这个时期的早期维管植物或植物根系）。作者认为：我国西南地区是探索早期陆生维管植物起源和早期演化的关键地区,通过一系列野外和室内研究,进一步强化对P.qianensis及其共生植物群的研究,并采用多学科交叉的方法,系统揭示P.qianensis的生物学属性、分类系统及其生态环境,在早期植物演化上提出新观点和演化模式,推进早期陆生维管植物起源、演化的研究。

英文摘要：

Pinnatiramosus qianensis Geng, 1986, is an enigmatic fossil plant of the late Llandovery,whieh was discovered in Dongkala Village, Fenggang County, Guizhou Province. This plant comprises a lot of pinnately branching systems subtended from its irregular axis. And its axis contains a substantial strand of xylem elements featured with various types of bordered-pitting. The fossil specimens of P. qianensis were firstly found by the 108 Geological Team of Guizhou Province, and identified as Zosterophyllurn？ sp. by Li Xing-xue and Cai Chong-yang at Nanjing Institute of Geology and Palaeontology, CAS. Geng （1986） was the first person to described it. He named it as Pinnatirarnosus qianensis Geng. Geng believed that this algal tracheid existed in Wenlock Strata. Based on tratigraphy and more specimens the theory of biosdiscovered, Cai et al. （1996） concluded that P. qianensis is the earliest known vascular plants and the geological age is late Llandovery. Edwards et al. （2007） confirmed further that P. qianensis were collected from the late Llandovery bed. Here are three different viewpoints about P. qianensis ： 1. What is the geological age of rocks containing P. qianensis？ Geng （1986） considered P. qianensis to be ftom the Wenlock; Cai et al. （1996）, ftom the Upper Llandovery; Edwards et al. （1990） once believed it possibly from the Lower Permian. Recently, Edwards et al. （2007） have also supported that P. qianensis is recorded from the Upper Llandovery. Up to now, the geological age of rocks with P. qianensis is unanimously considered as Upper Llandovery. 2. Is P. qianensis the earliest known vascular plant？ Since a vascular bundle is present in the main and lateral axes, and it comprises tracheids with bordered pits and smooth tubes, Cai et al. （1996） asserted that P. qianensis is an earliest known vascular plant （Geng, 1986; Cai, 20052 Li and Chui, 1995; Cai and Li, 1995; Cai et al., 1995, 1996, 2004）. However, because no stomata and fertile structures have b