The lower Cambrian lobopodian Cardiodictyon resolves the origin of euarthropod brains
The lower Cambrian lobopodian Cardiodictyon resolves the origin of euarthropod brains
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DOI：
10.1126/science.abn6264
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发表时间：
2022-11
期刊：
影响因子：
56.9
通讯作者：
N. Strausfeld;X. Hou;M. E. Sayre;F. Hirth
中科院分区：
文献类型：
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作者：
N. Strausfeld;X. Hou;M. E. Sayre;F. Hirth
世纪以来，节肢动物头部和大脑的起源和进化一直没有一个统一的理论基础来调和不同的形态和系统发育关系。在这里，下寒武纪的Lobopodian Cardiodictyon catenulum的神经系统的化石提供了澄清，它揭示了一个不分节的头部和大脑，包括三个头状域，不同于其approximular躯干的同色异谱腹神经系统。每个域与前肠的三个组成部分之一和一对头部附属物对齐。与茎组节肢动物的形态学对应以及与现存泛节肢动物同源基因表达模式的比对表明，C.小链早于真节肢动物头部的进化，但与定义活螯肢动物和下颚动物脑的神经节相对应。描述寒武纪大脑起源节肢动物的进化起源可以追溯到寒武纪时期，关于这个物种的大脑起源一直存在争议。一个流行的观点是，真节肢动物的大脑部分是由神经节起源于腹神经系统。然而，Strausfield等人描述了一个来自寒武纪的超过5.2亿年的lobopodian的大脑结构，并发现大脑甚至在头部进化之前就已经分为三个独立的大脑组成部分（参见Briggs和Parry的观点）。这些发现支持了这一结论，即大脑和尾神经系统在这一群体中的进化不同。一个5.2亿年前的化石的神经系统确定了一个定义现代节肢动物大脑的统一架构。
For more than a century, the origin and evolution of the arthropod head and brain have eluded a unifying rationale reconciling divergent morphologies and phylogenetic relationships. Here, clarification is provided by the fossilized nervous system of the lower Cambrian lobopodian Cardiodictyon catenulum, which reveals an unsegmented head and brain comprising three cephalic domains, distinct from the metameric ventral nervous system serving its appendicular trunk. Each domain aligns with one of three components of the foregut and with a pair of head appendages. Morphological correspondences with stem group arthropods and alignments of homologous gene expression patterns with those of extant panarthropods demonstrate that cephalic domains of C. catenulum predate the evolution of the euarthropod head yet correspond to neuromeres defining brains of living chelicerates and mandibulates. Description Cambrian brain origin Arthropods trace their evolutionary origins back to the Cambrian Period, and there has been continued debate about the origin of the brain in this speciose group. A prevailing view has been that the euarthropod brain was partly composed of ganglia originating from the ventral nervous system. However, Strausfield et al. describe the structure of the brain in a lobopodian from the Cambrian that is over 520 million years old, and found that instead the brain was already divided into three separate cerebral components even before the evolution of the head (see the Perspective by Briggs and Parry). These findings support the conclusion that the cerebral and caudal nervous system evolved differently in this group. —SNV The nervous system of a 520-million-year-old fossil identifies a unifying architecture defining modern arthropod brains.