Divergent evolution of medusozoan symmetric patterns: Evidence from the microanatomy of Cambrian tetramerous cubozoans from South China
Divergent evolution of medusozoan symmetric patterns: Evidence from the microanatomy of Cambrian tetramerous cubozoans from South China
复制标题
水生动物对称模式的趋异演化：来自华南寒武纪四体立方动物显微解剖的证据
DOI：
10.1016/j.gr.2015.01.003
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发表时间：
2016-03-01
影响因子：
6.1
通讯作者：
Komiya, Tsuyoshi
中科院分区：
文献类型：
--
作者：
Han, Jian;Kubota, Shin;Komiya, Tsuyoshi
现存的水母动物及其中寒武纪祖先的基本特征是四重对称。传统上认为埃迪卡拉纪寒武纪过渡期间其早期祖先的对称模式是四体动物，但需要根据寒武纪五体水生动物化石重新考虑。在这里，我们对来自中国南方下寒武统宽川堡组的三个微小四体标本进行了显微解剖分析；它们表现出立方水母科的诊断特征，包括伞下腔深处成对但分离良好的径向触手、由克劳斯特拉连接的径向隔膜、伞下的冠状肌以及由十二个系带悬挂的环形帆膜。这些化石可能代表了立方体单系干群的三个新类群，我们基于包含 25 个类群和 107 个特征的数据矩阵的系统发育分析进一步证实了这一点。在这些立方水母化石和同时存在的五体动物中，标本ELISN31-31在其狭窄的血管腔和内皮层径向融合方面大多接近冠群立方水母。早期寒武纪水生动物候选者不同谱系之间的多种对称模式可能是在不同类别的水生动物中独立进化的。 (C) 2015 年国际冈瓦纳研究协会。由 Elsevier B.V. 出版。保留所有权利。
Living medusozoans and their Middle Cambrian ancestors are characterized fundamentally by four-fold symmetry. The symmetric pattern of their earlier antecedents during the Ediacaran Cambrian transition, traditionally expected to be tetramerous, needs to be reconsidered in the light of Cambrian pentamerous fossil medusozoans. Here we present a microanatomic analysis of three tiny tetramerous specimens from the Lower Cambrian Kuanchuanpu Formation in southern China; they display diagnostic characteristics of Cubomedusae, including paired but well-separated interradial tentacles deep in the subumbrellar cavity, interradial septa connected by claustra, coronal muscles at the subumbrella, and an annular velarium suspended by twelve frenula. These fossils likely represent three new taxa of a monophyletic stem group of cubomedusans, which is further confirmed by our phylogenetic analysis based on the data matrix with 25 taxa and 107 characteristics. Among these fossil cubozoans and co-occurring pentamerous forms, the specimen ELISN31-31 is mostly close to the crown-group Cubomedusae with regard to its narrow vascular cavity and the endodermic perradial fusion. Diverse symmetrical patterns among different lineages of early Cambrian medusozoan candidates might have been independently evolved in different classes of medusozoans. (C) 2015 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.