Problematic Ediacaran sail-shaped fossils from eastern Yunnan, China

This study focuses on a rare sail-shaped macrofossil, Alienum velamenus gen. & sp. nov. from the Jiangchuan Biota in Yunnan Province, China. The new species presented here possesses an unique bipartite body consisting of a wide unbranched, asymmetrical sail-shaped anterior section and a small narrow tail-like posterior section. The macrofossil of the new species is preserved through carbonaceous compression. Its appearance is different from known macroalgae but similar to Vetulicolia from the early Cambrian Chengjiang Biota. The anterior section of the new species, which is broad and smooth, shows only indistinctly arranged suspected gill slits and a nearly horizontal pharyngeal groove, without significant segmented structures. Owing to lack of samples, the specific biological properties and taxa of the new species are still undefined. The discovery of Alienum velamenus indicates that the Jiangchuan Biota is an exceptional lagerstätte with great potential for the preservation of Precambrian early life through carbonaceous compression. Furthermore, the Jiangchuan Biota shows significant differences in species diversity from the Miaohe Biota of the Doushantuo Formation and the Shibantan Biota of the Dengying Formation in the Three Gorges area of Hubei Province.