Two Unusual Small Shelly Fossils from the Lower Cambrian of Southeastern Shaanxi Province, China
Two Unusual Small Shelly Fossils from the Lower Cambrian of Southeastern Shaanxi Province, China
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DOI：
10.1666/13-065
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发表时间：
2014-04
期刊：
影响因子：
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通讯作者：
J. L. Moore;S. Porter;Guoxiang Li
中科院分区：
文献类型：
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作者：
J. L. Moore;S. Porter;Guoxiang Li
摘要磷酸盐化和磷酸盐化小壳化石是研究早寒武世动物演化的重要资料来源。虽然在了解这些化石中的一些方面取得了进展，但许多仍然是谜，无论是关于它们的系统发育亲和力还是孤立骨片所来自的动物的整体形态。本文描述了产于陕西省西乡县小湾地区灯影组西蒿坪段上、下寒武统（琼竹寺组或阿塔达阶组）中的两种罕见化石。第一个是帽状化石，我们将其描述为Cambroskiadeion xiaowanense新属新种。在它的凹面上，它有一个刺，刺的基部覆盖着许多半球形的疣。长刺表明这是一个片骨而不是一个单瓣壳，尽管它来自哪种动物仍然不清楚。类似的化石也被假设为哈氏瓣;虽然在目前的样本中哈氏骨片的稀有性反对这种观点，但这些化石可能是类似的多元素骨架的一部分。第二个化石是Acidocharacus longiconus Qin and Ding，1988;它只在西蒿坪段发现，由一个高的脊椎组成，通常带有倒钩或隆起，附着在一个圆形的圆锥形基部上。基部覆盖着类似于Cambroskiadeion上发现的疣。这些元素的功能，以及它们是内部的还是外部的，仍然未知。
Abstract Phosphatized and phosphatic small shelly fossils are a major source of information concerning the evolution of animals during the early Cambrian. Although progress has been made in understanding some of these fossils, many remain enigmatic, both with regard to their phylogenetic affinities and the overall morphology of the animal from which isolated sclerites came. Two unusual fossils from the upper lower Cambrian (Qiongzhusian or Atdabanian) Xihaoping Member of the Dengying Formation from Xiaowan, Xixiang County, southeastern Shaanxi Province, China are described herein. The first of these is a cap-shaped fossil we describe as Cambroskiadeion xiaowanense new genus and species. On its concave surface it bears a spine, the base of which is covered with numerous hemispherical verruculae. The long spine indicates that this was a sclerite rather than a univalved shell, although it remains unclear from what sort of animal it came. Similar fossils have been hypothesized to be halkieriid valves; although the rarity of halkieriid sclerites in the present samples argues against this view, it is possible these fossils are part of a similar multi-element skeleton. The second fossil is Acidocharacus longiconus Qin and Ding, 1988; it is known only from the Xihaoping Member and consists of a tall spine, often bearing barbs or bumps, attached to a rounded conical base. The base is covered with verruculae similar to those found on Cambroskiadeion. The function of these elements, and whether they were internal or external, remains unknown.