The Meishucunian Stage of south China provides a window on the radiation of skeleton-bearing metazoans at the beginning of the Cambrian. The section at Meishucun has been proposed as a candidate for a global stratotype of the Precambrian-Cambrian boundary. Fossils and Strata No. 24, by Qian Yi & Stefan Bengtson, presents a thorough reinvestigation of the bizarre Meishucunian biota on the basis of exquisitely preserved material. This monograph will become a central reference on the earliest Cambrian faunas and the problem of the Precambrian-Cambrian boundary.

Qian Yi & Stefan Bengtson: Palaeontology and biostratigraphy of the early Cambrian Meishucunian Stage in Yunnan Province, south China

Abstract: The skeletal fossils of the early Cambrian Meishucunian Stage from two key localities (Meishucun, Jinning County, and Xianfeng, Xundian County) in eastern Yunnan Province, China, are described and illustrated in detail to provide a basis for improved palaeobiological and biostratigraphical work. About 1250 new SEM illustrations (including a large number of stereo-pairs) of well preserved material are presented. The taxonomy is extensively revised. When biological and preservational variability are taken into account, the number of genera and species may be reduced through synonymy to about one third of that reported in the literature. Thirty-eight genera (2 of which are new) and 57 species (5 of which are new) are described. The biology and affinities of many of these taxa are also discussed, but excursions into supra-generic taxonomy are generally restrained. The Meishucunian biotas of Yunnan consist of three successive assemblages with very few taxa in common. The first, the Anabarites-Protohertzina-Arthrochites Assemblage, is dominated by Anabarites and other sedentary tube-dwelling organisms, but non-sedentary benthic mollusc-like fossils (Canopoconus) and probable predators (Protohertzina) also occur. The key elements of this fauna have a wide geographical distribution and may be compared with the earliest skeletal faunas on the Siberian Platform, the Canadian Cordillera, and other regions. The second, the Siphogonuchites-Paragloborilus Assemblage, is characterized by a great diversity of vagile mollusc-like and multisclerite-bearing animals, but also sedentary tube-dwellers and some possible predators (Cyrtochites and Yunnan-odus) occur. This fauna is largely endemic. The third. the Lapworthella-Tannuolina-Sinosachites Assemblage, is mainly characterized by widely distributed taxa of multisclerite-bearing animals (chancelloriids, Halkieria, Tannuolina, and Lap worthella). It has elements in common with late Atdabanian faunas in other regions of the world.