Multiple branching and attachment structures in cloudinomorphs, Nama Group, Namibia
Multiple branching and attachment structures in cloudinomorphs, Nama Group, Namibia
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DOI：
10.1130/g47447.1
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发表时间：
2020-09-01
期刊：
影响因子：
5.8
通讯作者：
Bowyer, Frederick
中科院分区：
文献类型：
--
作者：
Shore, Amy;Wood, Rachel;Bowyer, Frederick
埃迪卡拉-寒武纪的云形动物，其中包括云形动物，是第一个假定的骨骼后生动物。它们有一个底栖生态和管状，有机，或生物矿化堆叠漏斗形态，但未解决的系统发育的亲和力。罕见的二叉分支已被描述在Cloudina，但在这里，我们证明了存在多个（polytomous），二叉分支cloudinomorphs从微生物垫社区从纳马组，纳米比亚，所揭示的三维模型创建的连续部分。分支共享一个开放的中心腔，分支通过外部出芽实现。这些云形化石显示出彼此之间的附着和相互胶结，也显示出通过小管外骨骼结构与纳马卡拉瑟斯之间的附着和相互胶结，从而可能形成一个水平的框架。多歧分枝排除了对其他云形动物提出的双侧亲和性。这就提出了埃迪卡拉纪管状漏斗形态是趋同的可能性，而云形虫实际上可能代表了不同亲缘关系的类群。
The Ediacaran-Cambrian cloudinomorphs, which include Cloudina, are the first putative skeletal metazoans. They have a benthic ecology and tubular, organic, or biomineralized stacked funnel morphologies but an unresolved phylogenetic affinity. Rare dichotomous branching has been described in Cloudina, but here we demonstrate the presence of multiple (polytomous), dichotomous branching in cloudinomorphs from a microbial mat community from the Nama Group, Namibia, as revealed by three-dimensional models created from serial sections. Branches share an open, central cavity, and branching is achieved via external budding. These cloudinomorphs show attachment and mutual cementation to each other, and also to Namacalathus, via extratubular skeletal structures to potentially form a horizontal framework. Polytomous branching excludes a bilaterian affinity as proposed for other cloudinomorphs. This raises the possibility that the Ediacaran tubular, funnel morphology is convergent, and that cloudinomorphs may, in fact, represent taxa of diverse affinity.