More than 700 fossils from the Jiangchuan Biota in Yunnan Province, southwest China, dating 554-539 million years ago in the late Ediacaran, include early relatives of starfish, acorn worms, deuterostomes, and other bilaterians. Led by Dr. Gaorong Li of Yunnan University, the discovery—after nearly a decade of fieldwork—challenges the suddenness of the Cambrian explosion by showing diverse animal communities predated it. The results, published in Science (DOI: 10.1126/science.adu2291), feature exceptionally preserved carbonaceous films revealing fine details like digestive systems.
A collaborative team from Yunnan University (including Professors Peiyun Cong and Feng Tang, Associate Professor Fan Wei), Oxford University's Museum of Natural History and Department of Earth Sciences (Drs. Ross Anderson, Frankie Dunn, Luke Parry), uncovered the fossils at a site preserving a transitional ecosystem between Ediacaran and Cambrian worlds. Finds include worm-like bilaterians, early comb jellies, cambroernids with coiled bodies and tentacles, Margaretia-like tube structures, anchored animals with extendable tubular appendages (evoking Dune's sandworms), and mobile sausage-shaped worms with mouths, guts, and pharynxes. Unlike typical Ediacaran sandstone impressions, these carbonaceous films show intricate features such as invertible feeding structures and associations with algae. Lead author Dr. Gaorong Li, who began major excavations in mid-2022 expecting only algae, highlighted the diversity of deuterostomes—a group including vertebrates. Dr. Frankie Dunn noted ambulacrarians (relatives of starfish and acorn worms) imply contemporaneous chordates, while Dr. Luke Parry called it a 'transitional community.' Dr. Ross Anderson explained the rarity of prior fossils due to exceptional preservation here, suggesting a more gradual buildup to the Cambrian diversification. Associate Professor Fan Wei pointed to algae-preserved sites, Professor Feng Tang deemed it compelling evidence for late Ediacaran bilaterians, Joe Moysiuk emphasized 30-million-year divergence timing without negating the explosion, and Han Zeng urged verification as a potential breakthrough.