Early Carboniferous Chinese and Australian „Siphonodendron” (Anthozoa, Rugosa): ecological and geographical influence on taxonomy

Normal marine salinity is the main limiting factor for the Subclass Rugosa. Water depth and temperature are less critical. Individual characteristics of specimens and some characteristics of species are, however, excellent environmental indicators. Being distributed exclusively by larvae, Rugosa required free distribution by means of marine currents, as well as midway areas suitable for settlement and metamorphosis of the larvae. Not distance but rather geography and midway environments are therefore the limiting factors for their distribution, relationships and stratigraphic value. Siphonodendron and Siphonodendron-like (“Siphonodendron”) corals are discussed as examples of morphological similarity, but not necessarily representing a phylogenetic relationship. The known homeomorphy of European and western North American Siphonodendron taxa (Fedorowski & Bamber 2007) may be extended on the European, some southern Chinese and all south-eastern Australian Siphonodendron-like corals, but only the Chinese and SE Australian forms may be truly related. The latter relationship would extend the boundaries of the Early Carboniferous Australian rugose coral province. The Late Tournaisian age of the earliest Australian “siphonodendrons” indicates an ancestry of the coral fauna within the province (SE Australia and S China). A mechanism for north-westward migration of this fauna, from SE Australia to S China, is not clear