Reconsideration of the supposed naraoiid larva from the Early Cambrian Chengjiang Lagerstatte, South China

The Chengjiang Lagerstatte in the Lower Cambrian of South China yields a small, larva-like arthropod, which was considered to be a protaspis of naraoiids by many authors. The discovery of a large number of well-preserved specimens from many new localities has allowed the original study to be revised. The relatively large size, stable morphology and unusual structure of the appendages indicate that these specimens represent adults of a new arthropod, Primicaris larvaformis. The larva-like outline is considered to have arisen by the heterochronic process of progenesis. In addition, this animal displays primitive aspects of bodyplan and limb morphology that suggest a basal position within arachnomorphs, or perhaps even arthropods, and the similarities to the Vendian arthropod-like animal Pan vancorina probably provide an evolutionary link between Vendian forms and Cambrian arthropods.