Fossilized animal embryos from lower Cambrian rocks provide a rare opportunity to study the ontogeny and developmental biology of early animals during the Cambrian explosion. This paper reports possible animal embryos, along with sponge spicules, hyolithelminths, and linguliformean brachiopods, from the upper Shuijingtuo Formation limestone (Cambrian Stage 3) at Changyang, Hubei Province, South China. This limestone unit has carbonate carbon and oxygen isotopic compositions similar to the upper Shuijingtuo limestone in the Yangtze Gorges area. The Shuijingtuo embryo fossils were exposed by physical fracturing, extracted with acetic acid maceration, and observed in thin sections. They were examined using light microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopic elemental mapping, and micro-focus X-ray computed tomography. Most of them are poorly preserved, with a phosphatic envelope (interpreted as a chorion or fertilization envelope) surrounding sparitic calcite. In some specimens, a polygonal pattern is present on the surface, and these are interpreted as multicelled blastula embryos. In others, sets of grooves are present on the surface of a calcitic spheroidal structure, presumably representing the calcitic interior within the chorion; these grooves are superficially similar to annulations of Markuelia embryos, but their biological significance is unknown. Although their phylogenetic and taxonomic placement is largely unconstrained, the Shuijingtuo animal embryos indicate that chorions are taphonomically more robust and are selectively phosphatized. Embryos within the chorions, on the other hand, can be completely lost or entirely replaced by calcite, with only poorly preserved surficial structures. This style of preservation can be explained by a taphonomic switch from early phosphatization to later calcitization. This study illustrates the importance of combining physical fracturing with widely used acid digestion methods in the study of calcitized animal embryos, and it alludes to the possibility that many empty phosphatic vesicles recovered by acid digestion from Cambrian carbonates may be fossilized chorions.

A new species of boreopterid pterosaur from the new fossil locality, Heichengzi, Beipiao, western Liaoning, China allows a reassessment of the Boreopteridae. In this new analysis, three species, Boreopterus cuiae, Boreopterus giganticus n. sp., and Zhenyuanopterus longirostris, are included within the Boreopteridae united by the autopomorphic occurrence of two main tooth morphologies, an equal length of the tibia and femur, and weak feet. Other taxa previously placed within the Boreopteridae are not in a monophyletic group with the former three species. Boreopterus has fewer teeth and a shorter tooth row than that in Zhenyuanopterus. This new Boreopterus species has a large size, a piriform orbit, an extensively fenestrated lacrimal, and a posteriorly directed lacrimal process, that differs from Boreopterus cuiae.

The Order Asaphida was grouped by the presence of a ventral median suture and a globular protaspis. The Superfamily Trinucleoidea has been assigned to the Order Asaphida, based on the recognition of a globular protaspis in the Ordovician representatives of the group, and the presence of a ventral median suture in the middle Cambrian genus Liostracina which has been regarded as a primitive sister-group to the post-Cambrian trinucleoideans. Recent studies demonstrate that the ventral median suture and the globular protaspis could have evolved multiple times in the trilobite evolutionary history, casting doubt on the traditional concept of the Order Asaphida. Inclusion of the Trinucleoidea into the Order Asaphida, therefore, has to be tested. It has recently been revealed that Liostracina simesi Jago and Cooper, 2005 did not possess a ventral median suture, implying that there could have been variable types of ventral suture within the genus Liostracina. Here we report the ontogeny of Liostracina tangwangzhaiensis n. sp. from the Cambrian Series 3 (middle Cambrian) strata of Shandong Province of North China. The material for this study includes protaspides, which are of flat, benthic morphology, contrasting to the globular protaspid morphology of the Ordovician trinucleoideans. The benthic protaspid morphology of L. tangwangzhaiensis indicates an independent evolution of the globular protaspis within the Superfamily Trinucleoidea. Together with the variable types of ventral suture within the genus Liostracina, the benthic protaspid morphology of Liostracina leads us to propose that the Superfamily Trinucleoidea be excluded from the Order Asaphida.

Specimens from the Wheeler and Marjum Formations of Utah comprising an elongate stipe with freely projecting conical thecae are described as dithecoid graptolites, the first reported from these units. The Wheeler Shale specimens, assigned to Archaeolafoea monegettae (Chapman, 1919), provide the first record of Archaeolafoea Chapman, 1919 from the Cambrian of Laurentia and show clear fusellar structure in backscattered electron images, confirming a graptolite affinity for this taxon. Mastigograptus sp., described on the basis of a single well-preserved specimen from the Marjum Formation, shows for the first time in a Cambrian mastigograptid an arrangement of thecae similar to that known for Ordovician representatives of the genus.