A treasure trove of Cambrian secrets: Animal life exploded in diversity and form during the Cambrian period about 500 million years ago. Fu et al. describe an early Cambrian fossil site in China that contains a variety of specimens, more than half of which are previously undescribed (see the Perspective by Daley). The site rivals previously described Cambrian sites, such as the Burgess Shale, and should help to elucidate biological innovation and diversification during this period. Science , this issue p. 1338 ; see also p. 1284

Shell microstructure and mineralogy ofPelagiella madianensisZhou & 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 fromPelagiella, 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.

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 theNCB. Twenty molluscan species are identified, including one bivalve, three stem group gastropods, and 16 additional helcionelloids. Among these, six helcionelloid species are reported from theNCBfor the first time, and one new species,Parailsanella luonanensissp. 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 theNCBwas 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 helcionelloidFigurina 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.

Li, L.-Y., Zhang, X.-L., Yun, H. & Li, G.-X., October 2015. New occurrence of Cambroclavus absonus from the lowermost Cambrian of North China and its stratigraphical importance. Alcheringa 40, xxx–xxx. ISSN 0311-5518. The problematic Small Shelly Fossil Cambroclavus absonus is described from the Xinji Formation in the Longxian area, which is located near the southwestern margin of the North China Platform. The Xinji Formation, the basal rock unit of the Cambrian in the studied area, yields an assemblage of skeletal fossils that share many common elements with contemporary faunas from South Australia. Sclerites of C. absonus reported herein represent the first occurrence of the species outside Australia, thus extending the palaeogeographic range of the taxon to northern China. To date, palaeogeographic occurrences of Cambroclavus sclerites are restricted to the Peri-Gondwana realm, including South China, Australia, Tarim, Kazakhstan, North China and Western Europe. These occurrences are divided into a Southern Group realm and Northern Group realm. Stratigraphically, Cambroclavus occurs mostly in Cambrian Stage 3 and has three occurrences in Stage 5, separated by Stage 4 in which Cambroclavus has not yet been found. The first appearance datum of Cambroclavus in Cambrian Stage 3 is of importance for regional and inter-regional correlations. In particular, the presence of Cambroclavus absonus in North China allows species-level correlation between North China and South Australia. Luoyang Li [lly@stumail.nwu.edu.cn], Xingliang Zhang [xzhang69@nwu.edu.cn], Hao Yun [yunhao@stumail.nwu.edu.cn], Early Life Institute and State Key Laboratory Of Continental Dynamics, Department of Geology, Northwest University, Xian 710069, PR China; Guoxiang Li [gxli@nigpas.ac.cn], Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, PR China.