Overview
- The study published in Nature on June 3, 2026 reports three-dimensionally phosphate‑preserved colonies from the Xiannüdong Formation in southern Shaanxi Province that retain both skeletons and soft tissues.
- Researchers described new specimens of the previously known Protomelission gatehousei and named a new species, Dayingomelission hexaclitia, both represented by tiny millimetre-scale colonies.
- Phylogenetic analyses place both taxa inside crown-group Stenolaemata, a major bryozoan class, which implies the group originated earlier than the Ordovician and may extend back toward the Ediacaran.
- Exceptional preservation revealed diagnostic features — hexagonal zooid modules, membranous sacs, skeletal styles, and muscle fibres — that rule out earlier ideas the fossils were algae or isolated sclerites.
- The find closes a long-standing gap in the fossil record, shows the colonial body plan was already complex during the Cambrian radiation, and will prompt new searches in shallow reef deposits and revisions of early animal evolution models.