摘要翻译：
当棘皮动物被概念化为水力实体时，这个群体的早期进化可以在描述双侧祖先（肠膜样生物）如何逐渐进化成五足棘皮动物的情景中呈现。根据这种情况，手臂是从双侧翼鳃样中间的前/后体轴长出来的。当肠道的U形肠系膜形成环，相应地，肠系膜的张力弦以五个环的形式附着在体壁时，这些赘生物就发展起来了。在体腔的液压作用下，这些张力弦区域之间的壁面可能会凸出。原本或多或少圆形的体腔，变形成了五个凸起的pneu。肠道的环迫使一个大致对称的排列，这是由一个物理事实增强的：五个pneu以及一个有五个内部系绳的pneu自然地采用“最小接触面”的五角大楼模式，作为最经济的排列。这些进化的转变伴随着某些组织学的改变，如易变的结缔组织和骨骼元素的发展，它们融合到听骨上，并以钙质骨骼的形式在体壁组织中提供形状稳定。结果生物是eleutherozoan棘皮动物的祖先（Ur-Echinoderm）。
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英文标题：
《Hydromechanical considerations on the origin of the pentaradial body
  structure of echinoderms》
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作者：
Michael Gudo
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最新提交年份：
2005
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分类信息：

一级分类：Quantitative Biology        数量生物学
二级分类：Populations and Evolution        种群与进化
分类描述：Population dynamics, spatio-temporal and epidemiological models, dynamic speciation, co-evolution, biodiversity, foodwebs, aging; molecular evolution and phylogeny; directed evolution; origin of life
种群动力学；时空和流行病学模型；动态物种形成；协同进化；生物多样性；食物网；老龄化；分子进化和系统发育；定向进化；生命起源
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一级分类：Quantitative Biology        数量生物学
二级分类：Other Quantitative Biology        其他定量生物学
分类描述：Work in quantitative biology that does not fit into the other q-bio classifications
不适合其他q-bio分类的定量生物学工作
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英文摘要：
  When echinoderms are conceptualized as hydraulic entities, the early evolution of this group can be presented in a scenario which describes how a bilateral ancestor (an enteropneust-like organism) gradually evolved into a pentaradial echinoderm. According to this scenario, the arms are outgrowths from the anterior/posterior body axis of the bilateral pterobranchia-like intermediate. These outgrowths developed when the originally U-shaped mesentery of the intestinal tract formed loops, and correspondingly, the tensile chords of the mesentery were attached to the body wall in five loops. The wall faces between these regions of tensile chords could bulge out under the hydraulic pressure of the body coelom. The originally more or less round body cavity was deformed into a pneu with five bulges. The loops of the gut forced a roughly symmetric arrangement, which was enhanced by a physical fact: five pneus as well as one pneu with five internal tethers, naturally adopt a pentaradial pattern of "minimum contact surfaces", as the most economic arrangement. These evolutionary transformations were accompanied by certain histological modifications, such as the development of mutable connective tissues and skeletal elements that fused to ossicles and provided shape stabilization in the form of a calcareous skeleton in the tissues of the body wall. The resultant organism was an ancestral eleutherozoan echinoderm (Ur-Echinoderm).
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PDF链接：
https://arxiv.org/pdf/q-bio/0505038