Early Cambrian biogeography in the North Atlantic region

Publisher Website
Google Scholar
Abstract
A model of Early Cambrian trilobite biogeography in the North Atlantic region (Theokritoff 1979, Lethaia 12, 281-295) is reviewed and modified in the light of new data. The presence of Wanneria in conglomerates bearing the Elliptocephala asaphoides fauna strengthens correlation of the E. asaphoides fauna as well as, by implication, the upper part of the Callavia Zone with the middle part of the Bonnia-Olenellus Zone. The faunas of the Bastion Formation of East Greenland and of the Devil''s Cove Limestone of northern Newfoundland [Canada] are reinterpreted as shelf faunas. Additional occurrences of Archacocyatha are noted in Spain and northwest Scotland but reports of Archacocyatha in northern Norway and East Germany are not authenticated. Neither Salterella nor ''Volborthella'' are now recognized as characteristic of any trilobite province. Although Ordovician acritarch provinces show congruence with trilobite provinces, available data on Early Cambrian plankton are not sufficient to support algal provincialism. Interpretation of the geological record suggests that the Early Cambrian Iapetus Ocean was stratified with a well-mixed oxygenated zone overlying a phosphate-rich oxgen minimum zone and that the Elliptocephala asaphoides fauna should be reinterpreted as a warm-water fauna.