Macroscopic worm-like body fossils from the upper precambrian (900-700 Ma), huainan district, anhui, China and their stratigraphic and evolutionary significance

Abstract

Abundant and varied, macroscopic, worm-like body fossils from the late Precambrian Liulaobei Formation, Huainan Group and the Jiuliqiao Formation, Feishui Group in the Huainan district, northern Anhui Province, China are further investigated through this progress report, after the initial discovery by Zheng Wenwu and a recent study by Wang Guixiang. Sinosabellidites Zheng in the Liulaobei Formation is a worm-like organism of questionable metazoan origin. It has merely a superficial resemblance with the tubes of late Vendian-early Cambrian true Sabelliditida but has much in common with the accompanying macroscopic algal remains of Tawuia Hofmann. Both Pararenicola Wang and Protoarenicola Wang are representatives of primitive worm-like animals in the Jiuliqiao Formation. Their macroscopic size, elongate cylindrical body, anterior aperture and apparatus, prominent and elastic annulations are characteristic for their metazoan origin, although they lack sufficient evidence for their definite relationship with any known kind of living worms. The Liulaobei Formation and the Jiuliqiao Formation are dated at about 850 Ma and 740 Ma, respectively. Regional geology and stratigraphic correlation and the occurrence of the distinctive Chuaria - Tawuia assemblage suggest a time range between less than 900 Ma and over 700 Ma for the whole shallow water marine sedimentary sequence of the Huainan and Feishui Groups; this latter group is disconformably covered by the drop-stone facies diamictites and tillites of the late Precambrian Luoquan Glaciation. Apart from the enigmatic Sinosabellidites, both Pararenicola and Protoarenicola are claimed to be the oldest multicellular animals so far discovered in the world and the first reliable evidence for the pre-Ediacarian evolutionary history of manifest metazoan life.