ACloudina-like fossil with evidence of asexual reproduction from the lowest Cambrian, South China

Abstract

AbstractThe earliest fossil record of animal biomineralization occurs in the latest Ediacaran Period (c. 550 Ma).CloudinaandSinotubulitesare two important tubular taxa among these earliest skeletal fossils. The evolutionary fate ofCloudina-type fossils across the Ediacaran–Cambrian transition, however, remains poorly understood. Here we report a multi-layered tubular microfossilFeiyanella manicagen. et sp. nov. from a phosphorite interval of the lowest Cambrian Kuanchuanpu Formation, southern Shaanxi Province, South China. This newly discovered fossil is a conical tube with a ‘funnel-in-funnel’ construction, showing profound morphological similarities toCloudinaandConotubus. On the other hand, the outer few layers, and particularly the outermost layer, ofFeiyanellatubes are regularly to irregularly corrugated, a feature strikingly similar to the variably folded/wrinkled tube walls ofSinotubulites. TheFeiyanellatubes additionally exhibit two orders of dichotomous branching, similar to branching structures reported occasionally inCloudinaand possibly indicative of asexual reproduction. Owing to broad similarities in tube morphology, tube wall construction and features presumably indicative of asexual reproduction,Cloudina, Conotubus, Sinotubulitesand the here describedFeiyanellamay thus constitute a monophyletic group traversing the Ediacaran–Cambrian boundary. The tube construction and palaeoecological strategy ofFeiyanellaputatively indicate evolutionary continuity in morphology and palaeoecology of benthic metazoan communities across the Ediacaran–Cambrian transition.