近日，西北大学张志飞团队报道了高保真模块化骨架证实苔藓虫起源于寒武纪。2026年6月3日出版的《自然》杂志发表了这项成果。

主要动物门类的身体构型均起源于寒武纪大爆发，但苔藓动物门（Bryozoa）却一直是这一模式中一个显著的例外。最初发现的Protomelission gatehousei曾为苔藓动物门的寒武纪起源提供了有力证据，使其与其他主要后生动物门类相一致，并且与独立的分子钟估算结果相吻合。然而，由于缺乏确切的软组织解剖学特征和诊断性的骨骼显微结构，其系统发育亲缘关系仍存在争议且悬而未决。

研究组报道了来自中国早寒武世仙女洞组的 P. gatehousei以及一个新分类单元——Dayingomelission hexaclitia（新属新种）的精美化石。这些标本原位保存了模块化骨骼中的磷酸盐化软组织，揭示了关键的解剖结构，包括柱状体、环肌、膜囊和环形隔膜。这一系列特征提供了确凿的证据，表明这些分类单元属于苔藓动物门。结合这些新特征进行的系统发育分析将它们鉴定为窄唇纲（stenolaemates）的冠群。

这些结果证实了苔藓动物门的寒武纪起源，并揭示了其在群体构型上出人意料的早期多样性，证明苔藓动物的多样化是寒武纪大爆发的一个组成部分。此外，分化的窄唇纲冠群的早期出现表明，苔藓动物干群的起源时间比最初显现的更为深远。

附：英文原文

Title: High-fidelity modular skeletons authenticate a Cambrian origin for Bryozoa

Author: Song, Baopeng, Zhang, Zhifei, Strotz, Luke C., Topper, Timothy P., Ernst, Andrej, Ma, Junye, Zhang, Zhiliang, Luo, Mei, Holmer, Lars E., Liang, Yue, Hu, Yazhou, Zhang, Caibin, Chen, Yanlong, Brock, Glenn A.

Issue&Volume: 2026-06-03

Abstract: The major animal body plans originated during the Cambrian explosion, yet the phylum Bryozoa has remained a conspicuous exception to this pattern1. The initial discovery of Protomelission gatehousei2 provided compelling evidence for a Cambrian origin for the Bryozoa, together with other major metazoan phyla and compatible with independent molecular clock estimates3,4,5,6,7. Nevertheless, the scarcity of definitive soft-tissue anatomy and diagnostic skeletal microstructure has left its phylogenetic affinities ambiguous and debated8,9. Here we report exquisite fossils of P.gatehousei and a new taxon, Dayingomelission hexaclitia gen. et sp. nov., from the early Cambrian Xiannüdong Formation of China. These specimens preserve in situ phosphatized soft tissues in modular skeletons, revealing critical anatomical structures, including styles, annular muscles, membranous sacs and ring septa. This suite of traits provides definitive evidence that these taxa belong to the Bryozoa. Phylogenetic analysis incorporating these new features identifies them as crown group stenolaemates. These results confirm a Cambrian origin for the phylum and reveal an unexpected early disparity in colonial architecture, demonstrating that bryozoan diversification was an integral component of the Cambrian radiation. Moreover, the early appearance of a differentiated stenolaemate crown group indicates a still deeper origin for the bryozoan stem lineage than was first apparent.

DOI: 10.1038/s41586-026-10590-9

Source: https://www.nature.com/articles/s41586-026-10590-9