Fauna Cyathaxonia a wymieranie koralowców Rugosa na granicy fran-famen
Abstract
Drobne osobnicze koralowce Rugosa (fauna Cyathaxonia) pospolite są w dewonie środkowym, bardzo rzadkie we franie i ponownie rozkwitają w famenie, gdy pojawiają się nowe rodzaje. Takie rozprzestrzenienie sugeruje raczej pożywecki, a nie pofrański kryzys w badanej grupie. W Górach Świętokrzyskich fauna Cyathaxonia dość często występuje w utworach głębszego szelfu, głównie wieku eifelskiego i żyweckiego. Jej reprezentanci należą do rodzin Metriophyllidae, Laccophyllidae i Stereolasmatidae. Ta ostatnia jest typowa dla środkowego dewonu królestwa biogeograficznego Wschodnich Ameryk (EAR) i, obok zafrentidów Heliophyllum i sifonofrentidów „Breviphrentis” ze strefy łysogórskiej, reprezentuje w Górach Świętokrzyskich imigrantów z EAR do królestwa Starego Świata.
CYATHAXONIA FAUNA AND EXTINCTION THE RUGOSE CORALS AT THE FRASNIAN-FAMENNIAN BOUNDARY
Summary
Published data on distribution of Devonian tetracorals (Oliver & Pedder 1979 and other sources) indicate that small solitary rugose corals (Cyathaxonia fauna) are rather common in the Middle Devonian, but relatively rare in the Frasnian and again numerous in the Famennian, with many new genera appearing after the Frasnian-Famennian boundary (Table 2), so fatal for most of the tetracorals. Possibly the main crisis of the Cyathaxonia fauna occurred at some time between the Givetian and Frasnian, when total decrease of diversity of the Rugosa affected the Cyathaxonia jauna to jar greater degree than the other tetracorals. In the Holy Cross Mountains the Cyathaxonia fauna (Tab. l) represents the relatively offshore, non-reefal settings of the Eifelian and Givetian in the Łysogóry basin (Fig. l) and it is almost totally lacking in the central shallow-marine Kielce carbonate platform. The
fauna belongs to Metriophyllidae (2 species of the genus Metriophyllum), Laccophyllidae (8 species of the gen era Metrionaxon, Syringaxon and Guerichiphyllum) and Stereolasmatidae (1 species of Stewartophyllum). The latter species, if correctly identified, belongs to the family typical of the Middle Devonian of the Eastern Americas (Oliver, 1977) and, jointly with a few zaphrentid species (Heliophyllum) and siphonophrentids ("Breviphrentis") - see Różkowska in Pajchlowa (1957) - represents the immigrants from Eastern Americas to the European area of the Old World Realm.
CYATHAXONIA FAUNA AND EXTINCTION THE RUGOSE CORALS AT THE FRASNIAN-FAMENNIAN BOUNDARY
Summary
Published data on distribution of Devonian tetracorals (Oliver & Pedder 1979 and other sources) indicate that small solitary rugose corals (Cyathaxonia fauna) are rather common in the Middle Devonian, but relatively rare in the Frasnian and again numerous in the Famennian, with many new genera appearing after the Frasnian-Famennian boundary (Table 2), so fatal for most of the tetracorals. Possibly the main crisis of the Cyathaxonia fauna occurred at some time between the Givetian and Frasnian, when total decrease of diversity of the Rugosa affected the Cyathaxonia jauna to jar greater degree than the other tetracorals. In the Holy Cross Mountains the Cyathaxonia fauna (Tab. l) represents the relatively offshore, non-reefal settings of the Eifelian and Givetian in the Łysogóry basin (Fig. l) and it is almost totally lacking in the central shallow-marine Kielce carbonate platform. The
fauna belongs to Metriophyllidae (2 species of the genus Metriophyllum), Laccophyllidae (8 species of the gen era Metrionaxon, Syringaxon and Guerichiphyllum) and Stereolasmatidae (1 species of Stewartophyllum). The latter species, if correctly identified, belongs to the family typical of the Middle Devonian of the Eastern Americas (Oliver, 1977) and, jointly with a few zaphrentid species (Heliophyllum) and siphonophrentids ("Breviphrentis") - see Różkowska in Pajchlowa (1957) - represents the immigrants from Eastern Americas to the European area of the Old World Realm.