Taxonomy and evolution of late Tournaisian and Visean (early Carboniferous) Heterostrotioninae (Rugosa, Anthozoa) from SE China

摘要

Colonial rugose corals with a heterocoral-like septal pattern are diverse and common in the Tournaisian-Visean (Mississippian) of South China. Numerous species were named in classical works but most of them require systematic revision. Newly collected material allowed eight Heterostrotion species to be recognized (ranging from the upper Tournaisian up to the middle Visean), including a new species H. huaqiaoense; three Stylostrotion species (middle Visean), including a new species S. houi and four Polygonaria species (upper Tournaisian and upper Visean). Heterostrotion as the oldest genus of the Stylostrotionidae probably originated in the western Palaeotethys and migrated to South China during the Tournaisian. The development of the cerioid genus Polygonaria from large-sized Heterostrotion during the late Tournaisian is described. The origin of Stylostrotion is however proposed in the evolution of Heterostrotion by a reduction of the minor septa and the development of a columella during the middle Visean. Stylostrotion is known only from China, where it seems to have evolved by homeomorphy with Siphonodendron, which only occurred in that area in the late Visean.