贵州织金寒武系戈仲伍组赫尔克壳类(Halkieria)的研究

STUDY ON HALKIERIA FROM THE CAMBRIAN GEZHONGWU FORMATION IN GUIZHOU PROVINCE

Halkieria是一类体表具贝壳状壳体和多种类型钙质骨片的两侧对称动物,多以离散骨片形式保存于全球寒武纪地层中,但其系统发育位置仍存在较大争议。本文系统研究了贵州织金戈仲伍剖面戈仲伍组磷块岩中的Halkieria,根据骨片形态鉴定出1属2种(Halkieria uncostatus,H.elongus),描述了其基本形态特征及纤维束等显微结构,观察到骨片表面具叠瓦状纹饰及平行纵脊排列的瘤状突起、孔洞。此外,运用多元统计分析方法探讨了Halkieria与其他冠轮动物类群之间的亲缘关系。聚类分析及主坐标分析结果表明,Halkieria与托莫特壳类的骨片形态特征相似性较高,推测Halkieria与托莫特壳类的亲缘关系更近,而与威瓦西亚虫间的亲缘关系相对较远。

Halkieria is a bilaterally symmetrical metazoan from the Cambrian,with large shell plates on both anterior and posterior parts of the body.It possesses a diverse array of calcareous sclerites and forms several regular longitudinal bands on the dorsal surface.Halkieria is commonly preserved as isolated sclerites in Cambrian deposits worldwide.However,its phylogenetic affinity has long been indetermined and controversial.In this paper,one genus and two species of Halkieria(Halkieria uncostatus,H.elongus)were identified based on morphological characters on sclerites.The microstructure of fiber bundle,imbricate-plating ornamentations,tubercles and holes arranged in parallel to the longitudinal ridges on the surface of the sclerites were observed.Cluster analysis and principal coordinate analysis show that Halkieria shares high similarities in the sclerite morphology with tommotiids rather than that with wiwaxiids,indicating the phylogenetic affinity of Halkieria is more close to tommotiids.