Early Ordovician black corals from China

Despite the importance of black corals in modern coral faunas and marine ecosystems, they were unknown in the fossil record until the recent discovery of abundant phosphatised remains in the Lower Ordovician Fenxiang Formation in the Three Gorges area (Hubei Province) of South China. The poor fossil record of black corals could be explained by their unmineralized skeleton composed mainly of laminar chitin complexed with the protein antipatharin. Here, we describe three species of black corals from the Fenxiang Formation: Sinopathes reptans Baliński, Sun & Dzik, 2012, Sinopathes sp., and Sterictopathes radicatus gen. et sp. nov. A new family Sinopathidae is proposed for the Early Ordovician genera Sinopathes and Sterictopathes. Coralla of both these genera consist of an encrusting basal plate and ascending branches, both covered with long spines. However, whereas in Sinopathes the surface of the skeleton is smooth and all spines are longitudinally striated, in Sterictopathes the spines are smooth, but basally buttressed by radiating, plate-like ridges forming anastomosing network on basal plate and branches. Biotic interactions among studied black corals and other organisms in the form of bioimmuration, encrustation and probable parasite/predatory markings are also described