Abstract
The earliest known Cyrtina in the Prague Basin has been discovered in the Kotýs Limestone of the Lochkov Formation (Lochkovian) among a rich brachiopod-coral fauna at Branžovy ridge near Bubovice (Beroun District, Czechia). Rare and imperfectly preserved silicified shells are assigned to Cyrtina praecedens Kozłovski, 1929, a species originally described from Podolia, Ukraine. The species is known also in north-eastern Russia (Tajmyr and Sette-Daban Mts) and likely also in New South Wales, Australia. Its distribution provides evidence of the rapid spread of Cyrtina across the shallow shelves of Laurussia, Siberia and Gondwana in the Early Devonian. The Devonian and Carboniferous distribution of Cyrtina is restricted to the agitated, shallow-water carbonate environment in tropical and temperate climatic belts.