New Data of Eoandromeda Octobrachiata and Their Indications
八臂仙母虫(Eoandromeda octobrachiata)新材料及其意义

Recent discoveries in South China show that the Ediacaran Doushantuo macrofossil Eoandromeda octobrachiata had a high conical body with eight arms in helicospiral arrangement along the flanks. The arms carried transverse bands supposed to be homologous to ctenophore ctenes (comb plates). Eoandromeda is interpreted as an early stem-group ctenophore, characterized by the synapomorphies ctenes, comb rows, and octoradial symmetry, but without crown-group synapomorphies such as tentacles, statoliths, polar fields, and biradial symmetry. Some exceptionally preserved fossils still have distinct central ring concatenated with eight comb-row-type arms. The authors infer that this derived apicalorgan-like or mouthlip-like structure as in crown coelenterata might be related to the development of neural or sensory system and the ability of locomotion or prey, and that the octoradial taxon probably had a pelagic mode of life. The early appearance in the fossil record of octoradial ctenophores is most consistent with the Planulozoa hypothesis (Ctenophora is the sister group of Cnidaria+Bilateria) of metazoan phylogeny.