![\"Reconstruction](\"https:\/\/cdn.sci.news\/images\/enlarge13\/image_14816_1e-Cambrian-Bryozoans.jpg\")
<\/a><\/p>\nReconstruction of the Early Cambrian seafloor, depicting colonies of Protomelission gatehousei and Dayingomelission hexaclitia living among archaeocyath reefs in shallow seas approximately 520 million years ago. Image credit: Zhifei Zhang.<\/p>\n
\u201cBryozoans<\/a> are tiny, filter-feeding colonial invertebrates that thrive in the world\u2019s oceans today, yet for decades their origins presented a puzzling gap in the fossil record,\u201d said Dr. Timothy Topper, a paleontologist at Northwest University and the Swedish Museum of Natural History, and his colleagues.<\/p>\n \u201cWhile nearly every other major animal group made its first appearance during the Cambrian explosion roughly 530 million years ago, the bryozoan fossil record remained stubbornly silent until the Ordovician period, some 50 million years later.\u201d<\/p>\n In a new study, the paleontologists examined exquisite bryozoan fossils from the Early Cambrian Xiann\u00fcdong Formation<\/a> of China.<\/p>\n The specimens represent two species: the previously known Protomelission gatehousei<\/a> and an entirely new taxon, Dayingomelission hexaclitia.<\/p>\n \u201cBryozoa has been the elephant in the room of Cambrian paleontology for a long time,\u201d Dr. Topper said.<\/p>\n \u201cEvery other major animal phylum had a Cambrian representative, except bryozoans. These fossils, finally close that chapter for good.\u201d<\/p>\n Specimen of Protomelission gatehousei from the Xiann\u00fcdong Formation in which the membranous sacs are preserved. Image credit: Song et al., doi: 10.1038\/s41586-026-10590-9.<\/p>\n Beyond simply filling a gap in the fossil record, the findings have profound implications for the tree of life.<\/p>\n A phylogenetic analysis places both Protomelission gatehousei and Dayingomelission hexaclitia firmly within the crown group Stenolaemata<\/a>, one of the three main classes of living bryozoans.<\/p>\n Because these fossils represent an already-advanced branch of the bryozoan family tree, their existence pushes the origin of the entire group even deeper, perhaps as far back as the Ediacaran period, before the Cambrian explosion even began.<\/p>\n The study also refutes previous theories that had questioned whether Protomelission gatehouse is a bryozoan at all, with some researchers suggesting it might instead be a green alga or isolated sclerites from an unrelated organism.<\/p>\n The new soft-tissue data, combined with detailed comparisons of colony size, shape, and internal structure, refute these alternative interpretations providing an unequivocal link to bryozoans.<\/p>\n<\/a><\/p>\n