New Benthic Fossils from the Late Ediacaran strata of southwestern China

Abstract

AbstractThe Jiangchuan Biota from the Jiucheng Member of the Dengying Formation, discovered in Jiangchuan, eastern Yunnan, China, is marked by copious macrofossils at the apex of the Ediacaran strata. This collection features benthic algae with varied holdfasts and macrofossils of indeterminate taxonomic affinity. It is compositionally unique compared to the Shibantan and Gaojiashan biotas of the Dengying Formation and the Miaohe and Wenghui biotas of the Doushantuo Formation. A novel benthic saccular macroalgal fossil from the Jiangchuan Biota is introduced in this study. These fossils are sausage‐shaped, elongate, tubular, ranging from 0.3 to 4 cm in length, and up to 0.8 cm in diameter. One terminus is blunt and rounded to an obtuse angle, the other is bent with a spread‐out surface resembling a holdfast, suggesting a three‐dimensional thallus. Thin, stipe‐shaped outgrowths, likely vestiges of sessile saccular life forms, are prevalent in macroalgal fossils of analogous size and shape. This finding augments the diversity of benthic algae known from the Longfengshan Biota in North China from the Early Neoproterozoic. The benthic macroalgal fossils in eastern Yunnan's Jiucheng Member might add to the evidence of Late Ediacaran metaphyte diversification and offer more clues about the evolutionary positioning of primitive macroalgae. The co‐occurrence of numerous planktonic and benthic multicellular algae and planktonic microbes may have ecologically facilitated the more extensive Cambrian explosion evidenced by the Chengjiang Biota.