Morphologically complex trace fossils, recording the infaunal activities of bilaterian animals, are common in Phanerozoic successions but rare in the Ediacaran fossil record. Here, we describe a trace fossil assemblage from the lower Dunfee Member of the Deep Spring Formation at Mount Dunfee (Nevada, USA), over 500 m below the Ediacaran–Cambrian boundary. Although millimetric in scale and largely not fabric‐disruptive, the Dunfee assemblage includes complex and sediment‐penetrative trace fossil morphologies that are characteristic of Cambrian deposits. The Dunfee assemblage records one of the oldest documented instances of sediment‐penetrative infaunalization, corroborating previous molecular, ichnologic, and paleoecological data suggesting that crown‐group bilaterians and bilaterian‐style ecologies were present in late Ediacaran shallow marine ecosystems. Moreover, Dunfee trace fossils co‐occur with classic upper Ediacaran tubular body fossils in multiple horizons, indicating that Ediacaran infauna and epifauna coexisted and likely formed stable ecosystems.

中文翻译：

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寒武纪大爆炸的预兆：来自美国内华达州的Ediacaran痕迹化石组合。

形态复杂的痕迹化石记录了双语动物的不育活动，在古生代中很常见，但在埃迪卡拉动物化石记录中却很少。在这里，我们描述了从邓菲山（美国内华达州）深春季组的较低邓菲成员的痕迹化石组合，该岩石在埃迪卡拉-寒武纪边界以下500 m以上。尽管Dunfee的规模为毫米级，并且在很大程度上不会破坏织物，但其组合却包含了寒武纪沉积物特有的复杂且具有穿透沉积物的痕迹化石形态。Dunfee组合记录了记录最深的沉积物渗透性贫化现象之一，证实了以前的分子学，水文学，以及古生态学数据表明，在晚期的Ediacaran浅海生态系统中存在着冠群类的生物和类生物的生态。此外，邓菲痕迹化石与经典的上层埃迪卡拉纪管状体化石同时出现在多个视野中，表明埃迪卡拉族的动物群和表生动物共存并可能形成稳定的生态系统。