Ediacaran metazoan reveals lophotrochozoan affinity and deepens root of Cambrian Explosion

Through exceptional preservation, we establish a phylogenetic connection between Ediacaran and Cambrian metazoans. We describe the first three-dimensional, pyritized soft tissue in Namacalathus from the Ediacaran Nama Group, Namibia, which follows the underlying form of a stalked, cup-shaped, calcitic skeleton, with six radially arranged lobes projecting into an apical opening and lateral lumens. A thick body wall and probable J-shaped gut are present within the cup, and the middle layer of the often-spinose skeleton and skeletal pores are selectively pyritized, supporting an organic-rich composition and tripartite construction with possible sensory punctae. These features suggest a total group lophotrochozoan affinity. These morphological data support molecular phylogenies and demonstrates that the origin of modern lophotrochozoan phyla, and their ability to biomineralize, had deep roots in the Ediacaran.

Automated summary

Through exceptional preservation, a phylogenetic connection between Ediacaran and Cambrian metazoans is established. The discovery of three-dimensional, pyritized soft tissue in Namacalathus provides evidence of a lophotrochozoan affinity and suggests deep roots of modern lophotrochozoan phyla in the Ediacaran period. This supports molecular phylogenies and demonstrates the early development of biomineralization abilities in these ancient organisms.