EVOLUTION & DEVELOPMENT 13:5, 408–414 (2011) DOI: 10.1111/j.1525-142X.2011.00499.x Eoandromeda and the origin of Ctenophora Feng Tang,a,b,∗ Stefan Bengtson,c,∗ Yue Wang,d Xun-lian Wang,e and Chong-yu Yina,b a Institute of Geology, Chinese Academy of Geological Sciences, Beijing, 100037, China b Key Laboratory of Stratigraphy and Paleontology, Chinese Academy of Geological Sciences, Beijing, 100037, China c Department of Palaeozoology and Nordic Center for Earth Evolution, Swedish Museum of Natural History, Box 50007, SE-104 05, Stockholm, Sweden d School of Resources and Environment, Guizhou University, Guiyang, 550003, China e School of Earth Sciences and Resources, China University of Geosciences, Beijing, 100083, China ∗Authors for correspondence (email:
[email protected] and
[email protected]) SUMMARY The Ediacaran fossil Eoandromeda octo- lacking crown-group synapomorphies such as tentacles, sta- brachiata had a high conical body with eight arms in he- toliths, polar fields, and biradial symmetry. It probably had a licospiral arrangement along the flanks. The arms carried pelagic mode of life. The early appearance in the fossil record transverse bands proposed to be homologous to ctenophore of octoradial ctenophores is most consistent with the Planulo- ctenes (comb plates). Eoandromeda is interpreted as an zoa hypothesis (Ctenophora is the sister group of Cnidaria + early stem-group ctenophore, characterized by the synapo- Bilateria) of metazoan phylogeny. morphies ctenes, comb rows, and octoradial symmetry but INTRODUCTION The new data on Eoandromeda suggest that it represents a stem-group ctenophore, implying that ctenophores were Megascopic biotas of the 635–541 Ma (million years ago) among the first eumetazoan lineages to appear, and that Ediacaran Period represent the foreplay to the “Cambrian planktic predators were present in the ecosystems already Explosion” of animals, but Ediacaran fossils are contentious during the heyday of the Ediacaran biota.