The early Cambrian fossil embryo Pseudooides is a direct-developing cnidarian, not an early ecdysozoan.
The early Cambrian fossil embryo Pseudooides is a direct-developing cnidarian, not an early ecdysozoan.
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早期寒武纪胚胎化石 Pseudooides 是直接发育的刺胞动物，而不是早期蜕皮动物
DOI：
10.1098/rspb.2017.2188
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发表时间：
2017-12-20
期刊：
影响因子：
--
通讯作者：
Donoghue PCJ
中科院分区：
文献类型：
--
作者：
Duan B;Dong XP;Porras L;Vargas K;Cunningham JA;Donoghue PCJ
早寒武世Pseudoides prima从胚胎和胚后发育阶段被描述，表现出长的胚带发育。关于这种分裂的模式一直存在一些争论，但这种解释，作为蜕皮动物的最早记录之一，已经被普遍接受。在这里，我们表明，“胚芽带”的P. prima胚胎分离沿着其中轴在发展过程中，与“体节”之间的横向沟展开到极孔的十边泡囊的Hexaconularia sichuanensis，传统上被解释为scyphozoan刺胞动物;共同发生的胚后残余的蜕皮动物是无关的。我们认出了H。sichuanensis作为P. prima的初级异名，因为这两个形式分类群被鉴定为同一生物体的不同发育阶段。在P. prima中的直接发育与共同存在的Olivoides和Quadrapyrgites平行，并且对一个新的表型数据集进行贝叶斯系统发育分析表明，尽管它们的四-，五-和假六-径向对称性存在差异，但这些hexangulaconulariids包括一个scyphozoan medusozoans的分支，Arthrochites和conulariids，它们都表现出从胚胎到thecate polyps的直接发育。hexangulaconulariids和olivooids的亲和力，现存的scyphozoan水母类表明，流行的四面体对称性和间接发展的痕迹，更广泛的身体计划对称性和发展模式，是表现在他们的早期中生代的同行。
Early Cambrian Pseudooides prima has been described from embryonic and post-embryonic stages of development, exhibiting long germ-band development. There has been some debate about the pattern of segmentation, but this interpretation, as among the earliest records of ecdysozoans, has been generally accepted. Here, we show that the ‘germ band’ of P. prima embryos separates along its mid axis during development, with the transverse furrows between the ‘somites’ unfolding into the polar aperture of the ten-sided theca of Hexaconularia sichuanensis, conventionally interpreted as a scyphozoan cnidarian; co-occurring post-embryonic remains of ecdysozoans are unrelated. We recognize H. sichuanensis as a junior synonym of P. prima as a consequence of identifying these two form-taxa as distinct developmental stages of the same organism. Direct development in P. prima parallels the co-occuring olivooids Olivooides, and Quadrapyrgites and Bayesian phylogenetic analysis of a novel phenotype dataset indicates that, despite differences in their tetra-, penta- and pseudo-hexa-radial symmetry, these hexangulaconulariids comprise a clade of scyphozoan medusozoans, with Arthrochites and conulariids, that all exhibit direct development from embryo to thecate polyp. The affinity of hexangulaconulariids and olivooids to extant scyphozoan medusozoans indicates that the prevalence of tetraradial symmetry and indirect development are a vestige of a broader spectrum of body-plan symmetries and developmental modes that was manifest in their early Phanerozoic counterparts.
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影响因子：
6.5
作者：
Lewis, PO
通讯作者：
Lewis, PO
DOI：
10.1016/j.cub.2015.09.066
发表时间：
2015-11-16
期刊：
Current biology : CB
影响因子：
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作者：
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发表时间：
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作者：
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作者：
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