Chancelloriids are a poorly understood group of phylogenetically problematic Cambrian metazoans; complete specimens show they were sessile, radially symmetrical, club‐shaped organisms covered with sclerites in the form of rosettes of spines. While isolated sclerites are common components of Cambrian shelly assemblages, they have been relatively little studied. We describe chancelloriid sclerites from a series of nine sections spanning the upper Dyeran to lower Delamaran stages (latest Stage 4 to perhaps basal Wuliuan) from the Pioche–Caliente region of east‐central Nevada, USA. Acid maceration of samples from the Combined Metals, Comet Shale and Susan Duster Limestone members of the Pioche Formation yielded more than 2000 sclerites. Based on careful examination of these sclerites and statistical analyses of co‐occurring sclerite types, we distinguish six species, each with a restricted stratigraphic range. Chancelloria impar Moore sp. nov. is the dominant species in most upper Dyeran samples. Archiasterella cometensis Moore sp. nov. and A. auriculata Moore sp. nov. are rare in the upper Dyeran but abundant in the lowest Delamaran; A. uncinata Moore sp. nov. and C. lilioides Moore sp. nov. replace these in younger samples. A. auriculata is noteworthy for sharing features with species of both Archiasterella and Chancelloria. These results provide further support for the taxonomic tractability and biostratigraphical utility of chancelloriid sclerites; large collections from single horizons allow intraspecific variability to be assessed and species to be distinguished. Our results document a taxonomic turnover in chancelloriids at the Dyeran–Delamaran boundary, showing that not only trilobites were affected at this time.

中文翻译：

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来自美国内华达州皮奥奇-加里恩特地区的代拉-德拉马兰（“下-中-寒武纪”）边界区间的斜纹硬岩

Chancelloriids是一类鲜为人知的系统发育问题的寒武纪后生动物。完整的标本表明它们是无柄的，径向对称的，棍状的生物，上面覆盖着以硬石的玫瑰花结石形式的巩膜。尽管孤立的硬质岩是寒武纪贝壳组合的常见组成部分，但对它们的研究却相对较少。我们描述了从内华达中东部的皮奥奇–加里恩特地区的上段Dyeran到下段Delamaran阶段（最新的第4阶段，也许是基底的Wuliuan）的9个剖面中的洋壳硬质岩。来自Pioche组的组合金属，页岩彗星和Susan Duster石灰石组合成员的样品进行了酸浸处理，产生了2000多个硬沸石。基于对这些硬脂岩的仔细检查和同时出现的硬脂岩类型的统计分析，Chancelloria impar Moore sp。十一月 是大多数上层Dyeran样本中的优势种。彗星阿奇氏菌Moore sp。十一月 和Auriculata Moore sp。十一月 在上代拉兰罕见，但在最低的德拉马兰丰富；A. uncinata Moore sp。十一月 和C. lilioides Moore sp。十一月 在年轻的样本中替换它们。A.蕨是值得注意的与两个物种共享功能Archiasterella和Chancelloria。这些结果进一步支持了芒chance硬核生物的分类学易处理性和生物地层学实用性。来自单一视野的大量采集可评估种内变异性并区分物种。我们的研究结果表明，在Dyeran-Delamaran边界的大虫类生物分类发生了翻新，这表明不仅三叶虫此时受到了影响。