湖南益阳下奥陶统的细弱匿笔石Adelograptus tenellus(Linnarsson,1871)  

ADELOGRAPTUS TENELLUS (LINNARSSON, 1871) FROM THE LOWER ORDOVICIAN OF YIYANG AREA, HUNAN PROVINCE

作　　者：王文卉[1] 冯洪真[1] 李丽霞[1] 李明[1] 陈文建[1] 

机构地区：[1]南京大学地球科学与工程学院,南京210093

出　　处：《古生物学报》2012年第2期186-199,共14页Acta Palaeontologica Sinica

基　　金：国家自然科学基金赞助项目(No.40972009)

摘　　要：湖南省益阳市南坝地区下奥陶统印渚埠组产出大量保存良好的细弱匿笔石Adelograptus tenellus(Linnarsson,1871)。在对该种进行详细的系统古生物学研究后,选取重要性状讨论该区A.tenellus的居群内形态变异。在此基础上,综合考虑A.tenellus各级枝的长度、胞管组合以及胞管密度等重要性状,将益阳地区的A.tenellus标本分为两种形态类型(类型Ⅰ和Ⅱ),并结合二者的地层分布,以及与北欧、英国、北美等地的对比,提出形态类型Ⅰ向形态类型Ⅱ的演替过程。认为英国、新西兰、皖南等地的A.tenellus与当前形态类型Ⅰ相似;北欧地区的A.tenellus则与当前形态类型Ⅱ较为相似。Abundant, well-preserved graptolites were collected from the Lower Ordovician in the Nanba area of Yiyang, Hunan Province. A population analysis of Adelograptus tenellus （Linnarsson, 1871） based on primary morphological characteristics such as the stipe length of each order,the number and arrangement of autothecae, and the thecal spacing realed two forms （Type I and Type II） in the Yiyang area. Comparing with areas such as North Europe, Great Britain and North American, an evolutionary lineage from Type I to Type II of these two types is suggested. The results show that Adelograptus tenellus reported from Great Britain, New Zealand and Southern Anhui Province is similar to Type I, whereas Adelograptus tenellus from Northern Europe shows a close similarity with Type II.

关 键 词：Adelograptus tenellus(Linnarsson 1871) 形态变异 下奥陶统 湖南益阳 

分 类 号：Q915[天文地球—古生物学与地层学]