Cambrian petalonamid Stromatoveris phylogenetically links Ediacaran biota to later animals

Macro-organisms of the Ediacaran period (635-541 Ma) were large and morphologically complex, with some living in aphotic habitats, presenting the possibility that they were early animals. However, ‘bizarre’ Ediacaran morphologies and mouldic preservation have frustrated comparison to later taxa. Consequently, both the positions of Ediacaran biota in the tree of life and the origins of the Metazoa have been unresolved. Here we provide phylogenetic evidence to identify Ediacaran macro-biota as animals, based on 206 new fossils of Stromatoveris psygmoglena from the Lower Cambrian Chengjiang Lagerstätte. Exceptionally preserved soft-tissue anatomy shows that Stromatoveris was a soft-bodied, radially symmetric animal with multiple, sub-branched petaloids and a differentiated holdfast. Photo-referenced morphological character analysis enables phylogenetic reconstruction of a monophyletic clade designated Petalonamae, following Pflug, 1970, that unites Stromatoveris with iconic Ediacaran gener...

埃迪卡拉纪（Ediacaran Period，635~541 Ma）的宏体生物体型庞大且形态复杂，部分类群栖息于无光生境，提示它们可能为早期动物。然而，埃迪卡拉纪生物“怪异”的形态以及铸型保存（mouldic preservation）方式，阻碍了其与后世生物类群的对比研究。因此，埃迪卡拉纪生物群在生命之树中的演化位置，以及后生动物（Metazoa）的起源问题，始终未能得到解决。
本研究基于采自下寒武统澄江特异埋藏化石库（Lower Cambrian Chengjiang Lagerstätte）的206枚新发现的*Stromatoveris psygmoglena*化石，提供了将埃迪卡拉纪宏体生物归为动物类群的系统发育证据。
异常完好保存的软组织解剖结构显示，*Stromatoveris*是一类具柔软躯体的辐射对称动物，拥有多个亚分枝的瓣状构造以及分化明确的固着器（holdfast）。
基于照片参照的形态性状分析，我们得以重建单系群（monophyletic clade）——花瓣动物类群（Petalonamae，遵循1970年Pflug的命名方案）的系统发育关系，该类群将*Stromatoveris*与标志性埃迪卡拉纪属级类群纳入其中。