Ou, Q.Xiao, S.Han, J.Sun, G.Zhang, F.Zhang, Z.Shu, D.2017-01-142017-01-142015-07http://hdl.handle.net/10919/74308Ctenophores are traditionally regarded as "lower" metazoans, sharing with cnidarians a diploblastic grade of organization. Unlike cnidarians, where skeletonization (biomineralization and sclerotization) evolved repeatedly among ecologically important taxa (for example, scleractinians and octocorals), living ctenophores are characteristically soft-bodied animals. We report six sclerotized and armored ctenophores from the early Cambrian period. They have diagnostic ctenophore features (for example, an octamerous symmetry, oral-aboral axis, aboral sense organ, and octaradially arranged ctene rows). Unlike most modern counterparts, however, they lack tentacles, have a sclerotized framework, and have eight pairs of ctene rows. They are resolved as a monophyletic group (Scleroctenophora new class) within the ctenophores. This clade reveals a cryptic history and sheds new light on the early evolution of this basal animal phylum. Skeletonization also occurs in some other Cambrian animal groups whose extant members are exclusively soft-bodied, suggesting the ecological importance of skeletonization in the Cambrian explosion.e1500092 - ? page(s)Creative Commons Attribution-NonCommercial 4.0 InternationalCambrianChengjiang biotaCtenophoraskeletonArticle - Refereedhttps://doi.org/10.1126/sciadv.150009216