近日，中国科学院南京地质古生物研究所朱茂炎及其团队在研究寒武纪早期Cambroclavus时取得新看法，他们认为Cambroclavus是一种与苔藓虫或钙藻无关的有巩膜真后生动物。相关论文于2023年12月12日发表于国际顶尖学术期刊《地质学》杂志上。

研究人员重新分析了Protomelission标本的显微计算机断层扫描数据，分析揭示了以前未发现的结构，表明Protomelission既不是苔藓虫也不是藻类，而是一种寒武纪早期的微化石Cambroclavus的巩膜节，这种微化石通常被发现为断裂的骨片。长期寻找的巩膜节表明，神秘的cambroclaves可能代表了一种已灭绝的上皮动物级的真后生动物，其表皮覆盖着多刺的巩膜以进行防御。

在寒武纪大爆发期间，像cambroclavus这样奇异的动物的流行，且缺乏现代类似物，意味着在那时动物身体结构的差异比之前认识到的要大得多。研究明确了早寒武纪苔藓虫化石的缺乏，进一步强调了苔藓虫起源的困境。

据介绍，长期以来，苔藓虫的起源一直是一个有趣的谜，主要是因为寒武纪地层中缺乏明确的苔藓虫化石，迄今为止发现的最早的苔藓虫 Protomelission，来自于澳大利亚和中国早寒武世微体化石，但其亲和性最近受到质疑被认为是一种钙藻。

附：英文原文

Title: Early Cambrian Cambroclavus is a scleritomous eumetazoan unrelated to bryozoan or dasyclad algae

Author: Kai Xiang, Zongjun Yin, Wei Liu, Fangchen Zhao, Maoyan Zhu

Issue&Volume: 2023-12-12

Abstract: The origin of Bryozoa has long been an intriguing mystery, largely due to the dearth of unambiguous bryozoan fossils within Cambrian strata. The earliest bryozoan thus far identified, Protomelission, an early Cambrian microfossil from Australia and China, was recently contested and proposed to be dasyclad algae. Our reanalysis of micro-computed tomography data from Protomelission specimens, however, unveils previously unrevealed structures, indicating Protomelission to be neither bryozoan nor alga, but a scleritome of Cambroclavus, an early Cambrian microfossil typically found as disarticulated sclerites. The long-sought scleritomes suggest that enigmatic cambroclaves likely represent an extinct group of epitheliozoan-grade eumetazoan, with spiny sclerites covering their epidermis for defense. The prevalence of bizarre animals like cambroclaves, lacking modern analogues, implies a greater disparity of animal body plans during the Cambrian explosion than previously recognized. Our findings underscore the absence of definitive early Cambrian bryozoan fossils, further highlighting the dilemma of the origin of Bryozoa.

DOI: 10.1130/G51663.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G51663.1/630598/Early-Cambrian-Cambroclavus-is-a-scleritomousredirectedFrom=fulltext