Review of some Frasnian ahermatypic coral localities from Germany and description of a new genus Spinaxon (Anthozoa, Rugosa, Upper Devonian)

1. IntroductionThe Palaeozoic superorder Rugosa passed through several crises before the final extinction at the Permian–Triassic boundary. The most important one, the global Upper Kellwasser Event at the Frasnian–Famennian boundary, led to the disappearance of all coral reefs; they reappeared during top-Famennian times (Strunian). For a long period, the coral world of the Famennian (both photic and aphotic zones) was a terra incognita – but this changed surprisingly after the monograph of Polish ahermatypic Famennian Rugosa (Rozkowska, 1969), and with the discovery of similar faunas mainly in Germany and Morocco, and also in northern China (Liao & Cai, 1987; Cai, 1988; Wu & Liao, 1988; Guo 1990). Knowledge about Famennian shallow water Rugosa increased more slowly: especially through Sorauf (1992: unique first upper Famennian, though pre-Strunian Rugosa fauna from North America) and Berkowski (2002: first upper Famennian, also pre-Strunian survivors of Frasnian Phillipsastreidae in Poland). Unfortunately, up to now there still are no certain Rugosa occurrences from the basal Famennian (Lower, Middle, and Upper Palmatolepis triangularis Zones, perhaps also Lower Palmatolepis crepida Zone). The only one Rugosa, which I could collect from the Middle Palmatolepis triangularis Zone, together with Nephranops incisus (Roemer, 1866), was an undeterminable ampleximorph taxon from Rubeland in the German Harz Mts.At present, the Upper Givetian and the Frasnian ahermatypic Rugosa are th