Burgess Shale–type fossil Lagerstätten provide the best evidence for deciphering the biotic patterns and magnitude of the Cambrian explosion. Here, we report a Lagerstätte from South China, the Qingjiang biota (~518 million years old), which is dominated by soft-bodied taxa from a distal shelf setting. The Qingjiang biota is distinguished by pristine carbonaceous preservation of labile organic features, a very high proportion of new taxa (~53%), and preliminary taxonomic diversity that suggests it could rival the Chengjiang and Burgess Shale biotas. Defining aspects of the Qingjiang biota include a high abundance of cnidarians, including both medusoid and polypoid forms; new taxa resembling extant kinorhynchs; and abundant larval or juvenile forms. This distinctive composition holds promise for providing insights into the evolution of Cambrian ecosystems across environmental gradients.

Shell microstructure and mineralogy of Pelagiella madianensis Zhou & Xiao, 1984, a globally distributed Cambrian micromollusk, are investigated based on abundant and extraordinarily well-preserved specimens from Xinji Formation, Longxian, Shaanxi, North China. Five types of aragonitic microstructures have been recognized. The lamello-fibrillar microstructure, previously known from Pelagiella, constructs the outermost shell layer, while the remaining four types are reported here for the first time in this genus. They include fibrous foliated, foliated aragonite, crossed foliated lamellar and isolated tablets. The animal constructs these five types of microstructures to build its shell in a complex hierarchical pattern with four orders: crystallite columns, laths, folia and lamellae. These findings demonstrate that the capability of building complex shell microstructures had already evolved by the Cambrian explosion. In addition, this work shows that early aragonitic shells were constructed with fibers, laths, folia and isolated tablets, indicating increased controls over biomineralization by the animal.

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A diverse group of molluscs from the Cambrian Series 2, Stages 3–4 Xinji Formation of the North China Block (NCB) is described, based on more than 4500 specimens from three well‐studied sections in Shaanxi and Henan provinces, along the southern and southwestern margin of the NCB. Twenty molluscan species are identified, including one bivalve, three stem group gastropods, and 16 additional helcionelloids. Among these, six helcionelloid species are reported from the NCB for the first time, and one new species, Parailsanella luonanensis sp. nov. is proposed. This diverse molluscan fauna shares a large number of species with contemporaneous faunas of South Australia (15), Antarctica (7), Laurentia (6), Siberia (3) and South China (1). Faunal similarities are even greater on a generic level. The striking similarities of the molluscan faunas of North China, South Australia and Antarctica strongly support the hypothesis that the NCB was situated close to Eastern Gondwana, most likely close to South Australia in the Cambrian Epoch 2. In addition, well‐preserved shell attachment muscle scars were observed in the helcionelloid Figurina figurina, with two pairs of symmetrical, continuous, band‐like muscle scars, which are obviously different from the musculature of both gastropods and monoplacophorans. Because of this unique musculature, these characteristic Cambrian cap‐like molluscs are assigned to the Helcionelloida rather than to the Gastropoda or Monoplacophora.

Although various types of shell microstructures are uncovered from Cambrian molluscs, precise organization and mineralogical composition of Terreneuvian molluscs are rarely known. Anabarella was one of the first helcionellid molluscs to appear in the Terreneuvian, and ranged up to Cambrian Epoch 3 in age. Here, shell microstructures of Anabarella australis have been studied based on new collections from the lowermost Cambrian (Series 2) Xinji Formation of the North China Block.Results show that A. australis has a laminar inner shell layer that consists of crossed foliated lamellar microstructure (CFL). Nacreous, crossed-lamellar and foliated 2 aragonite microstructures previously documented in Terreneuvian A. plana are here revised as preservational artefacts of the CFL layers. This complex skeletal organization of Anabarella suggests that mechanisms of molluscan biomineralization evolved very rapidly. Morphologically, specimens from the Chaijiawa section show a distinct "pseudo-dimorphism" pattern as external coatings are obviously identical to Anabarella, while associated internal moulds are similar to the helcionelloid genus Planutenia. In contrast, internal moulds from the Shangzhangwan section show considerable morphological variation owing to preservational bias, which are more similar to specimens from South Australia, Northeast Greenland and Germany. These observations demonstrate that the wide morphological variants of internal moulds of Anabarella worldwide are in large part preservational artefacts, and are unlikely to represent the real intra-and interspecific variability of the animal. In these cases, Planutenia is confirmed to be a subjective synonym of Anabarella.