Fossils Reveal Bryozoans' Presence During Cambrian Explosion
Recent fossil discoveries in the Xiannüdong Formation of southern Shaanxi Province, China, have solved a long-standing mystery about the origins of bryozoans, tiny colonial invertebrates. These fossils, dating back to the early Cambrian period approximately 520 million years ago, confirm that bryozoans were present during the Cambrian explosion, a time when most major animal groups first appeared. The fossils include new specimens of Protomelission gatehousei and a new taxon, Dayingomelission hexaclitia. The preservation of these fossils is exceptional, with internal soft tissues intact, providing definitive evidence of their bryozoan affinity. This discovery fills a significant gap in the fossil record and suggests that bryozoans were already diversifying during the Cambrian radiation. 
