湖北房县下寒武统西蒿坪段钉形骨片化石  

NAIL-SHAPED SCLERITE FOSSILS FROM THE LOWER CAMBRIAN XIHAOPING MEMBER OF FANGXIAN,HUBEI PROVINCE

作　　者：那琳[1] 李国祥[1] 

机构地区：[1]中国科学院南京地质古生物研究所,现代古生物学与地层学国家重点实验室,南京210008

出　　处：《微体古生物学报》2011年第3期284-300,共17页Acta Micropalaeontologica Sinica

基　　金：中国科学院创新工程重要方向性项目(KZCX2-EW-115);国家自然科学基金项目(No.40872012)资助

摘　　要：本文对采自湖北房县三座庵剖面下寒武统西蒿坪段的钉形骨片(nail-shaped)化石进行了研究,系统厘定和描述了2属2种,分别为Parazhijinites guizhouensis和Cambroclavus fangxianensis;其中以C.fangxianensis骨片化石最为丰富,由三种类型的骨片组成,它们可能分属于动物躯体不同部位的骨片。寒武纪早期钉形骨片化石主要包括织金钉类(zhijinitids)和寒武钉类(cambroclavids),织金钉类骨片在其动物躯体表面呈零散分布,寒武钉类骨片在其动物躯体表面呈联锁(骨片基部相互关联)分布。由于两类骨片外形非常相似,它们常被归入一个科(Zhi-jinitidae),但这种形态分类的可靠性尚有疑问,因为不同类别的动物可以生长有形态近似的骨片,而骨片的形态相似性在动物分类方面的作用有时可能被人为地扩大了。由于缺乏软躯体特异保存化石的发现,尚难确定这些骨片化石究竟与哪类动物相关,暂作分类未定的骨片化石。A distinct feature of the early Cambrian skeletal fauna is the wide occurrence of disarticulated sclerite fossils,many of which are so far unknown with their scleritomes and zoological affinities.The nail-shaped fossils,including zhijinitids and cambroclavids,have a common form of a base and projecting spine and are a characteristic group among the enigmatic sclerites.Zhijinitid sclerites have an approximately circular base and a long dorsal spine,and possibly occur as isolated hard parts on the zhijinitid animals.Cambroclavid sclerites usually have a variable elongate base and a spine at the anterior end.Discovery of fused sclerites and articulatory facets on sclerites implies that the cambroclavid scleritome could form interlocking arrays（Conway Morris,1997）.Although zhijinitids and cambroclavids are usually assigned to the family Zhijinitidae on the basis of morphological similarities of their sclerites,biological affinities and their relations are so far unresolved.Without soft-bodied preservation,it is rather difficult to evaluate the function of these sclerites bearing on their biological affinities.It could not exclude that morphological similarities of the sclerites may be due to convergence.The nail-shaped sclerites described in this paper were collected from the Xihaoping Member at the Sanzuoan section,Fangxian County,Hubei Province.Systematically,two species,including Parazhijinites guizhouensis and Cambroclavus fangxianensis,are described in detail.Parazhijinites guizhouensis comes from the basal part of the Xihaoping Member,co-occurring fossils including Neogloborilus spinatus,Hyolithellus cf.micans,Archaeospira ornata,Allonnia erromenosa,Archiasterella pentactina,Chancelloria sp.,Halkeria sp.,etc.This assemblage indicates the basal part may be of the late Meishucunian in age.While the major part of the Xihaoping Member is of the Qiongzhusian in age for the occurrence of C.fangxianensis,Ninella,Microdictyon and linguloid brachiopods.C.fangxianensis shows extensive morphological variability and th

关 键 词：钉形骨片 织金钉类 寒武钉类 西蒿坪段 下寒武统 房县 湖北 

分 类 号：Q915[天文地球—古生物学与地层学]