钉形类(nail-shaped)骨片化石是华南寒武纪早期地层中常见的一类具矿化骨骼的小壳化石。本文系统研究了贵州织金戈仲伍剖面寒武系戈仲伍组的钉形类骨片化石, 发现织金地区钉形类化石主要以织金钉类和疑似的寒武钉类为主, 共4属9种。相较于前人研究, 本文新发现了织金钉类: Zhijinites tumourifomis、Z. lubricus、Z. clavus, 和疑似的寒武钉类: ?Deiradoclavus sp.、?Cambroclavus sp.。排除埋藏学假象后, 分析了钉形类不同化石属种保存方式及形态结构, 发现Zhijinites的多数种都存在盘体顶面凹陷结构, 并且Zhijinites部分种的锥体内壁有收缩现象或具有十字交错纤维结构, 这些发现能较好地揭示出Zhijinites各形态种间的相似性和差异性。分析钉形化石时空分布特点发现, 目前钉形类骨片化石最早在织金地区有化石记录, 之后在扬子地台内部辐射扩散, 并几乎同时辐射扩散至邻近陆块。此外, 本文讨论的疑似寒武钉类化石时代可下延至寒武纪幸运期, 可能是目前该类化石在全球的最早记录, 为探索寒武钉类化石的系统演化和地层学意义提供了新信息。

Nail-shaped sclerites are common small shelly fossils (SSFs) with mineralized sclerites in the early Cambrian strata of South China. In this paper, we focus on the systematic study of the nail-shaped sclerites from the Gezhongwu Formation in Zhijin County, Guizhou Province. The results show that these nail-shaped fossils are mainly composed of zhijinitids and problematic cambroclavids. They include nine species in four genera with some taxa first found in Zhijin County, such as Zhijinites tumourifomis, Z. lubricus, Z. clavus, ?Deiradoclavus sp. and ?Cambroclavussp. Based on observations of their preservation modes and morphology, we find that different nail-shaped fossil species have different structures, such as the contracting inner wall of the spine and the vertically crossed fibers in some specimens of Zhijinites and the concave structure on the bottom surface of the plates of many Zhijinites species, indicating morphological similarities and variations in different genera and species. Analysis of the spatial and temporal distributions of these nail-shaped sclerites suggests that they first occurred in the Zhijin area, then radiated and spread to other areas of the Yangtze Platform and adjacent landmasses. In addition, this problematic cambroclavids from the lower part of Gezhongwu Formation may represent the earliest record of this group and extends its age to the Fortunian, providing new important information for the discussion of their evolution and stratigraphic significance.

国家自然科学基金(42262003, 42330209)和贵州省科技计划项目(黔科合支撑[2020]4Y241号)联合资助