Reconstructing the function and behaviour of extinct groups of echinoderms is problematic because there are no modern analogues for their aberrant body plans. Cinctans, an enigmatic group of Cambrian echinoderms, exemplify this problem: their asymmetrical body plan differentiates them from all living species. Here, we used computational fluid dynamics to analyse the functional performance of cinctans without assuming an extant comparative model. Three‐dimensional models of six species from across cinctan phylogeny were used in computer simulations of water flow. The results demonstrate that cinctans with strongly flattened bodies produced much less drag than species characterized by dorsal protuberances or swellings, suggesting the former were more stable on the seafloor. However, unlike the flattened forms, cinctans with high‐relief bodies were able to passively direct flow towards the mouth and associated food grooves, indicating that they were capable of more efficient feeding on particles suspended in the water. This study provides evidence of a previously unknown evolutionary trade‐off between feeding and stability in Cambrian cinctan echinoderms.

中文翻译：

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寒武纪辛丹棘皮动物摄食与稳定性之间的潜在进化权衡

重建已绝种的棘皮动物的功能和行为是有问题的，因为没有现代的类似物可用于其异常的身体计划。Cinctans是寒武纪棘皮动物的一个神秘团体，它例证了这一问题：他们不对称的身体计划使他们与所有活着的物种区分开。在这里，我们使用计算流体动力学来分析五溴二苯醚的功能性能，而无需假设现有的比较模型。跨辛丹发展史的六个物种的三维模型被用于水流的计算机模拟。结果表明，与具有背隆或肿胀特征的物种相比，具有高度扁平化特性的Cinctans产生的阻力要小得多，这表明前者在海底更稳定。但是，与拼合形式不同，具有高浮雕体的辛烷能够被动地将水引向口腔和相关的食物槽，这表明它们能够更有效地捕食悬浮在水中的颗粒。这项研究提供了以前未知的寒武纪辛丹棘皮动物进食与稳定性之间的进化折衷的证据。