Lower Ordovician bivalve molluscs from the quartzitic facies of the Central lberian Zone (Spain)

4 páginas, 1 figura.-- Trabajo presentado en la 22ª Sesión Científica, Bilbao 1997.Some scarce and bad preserved bivalves have been described from few localities lying at the upper part of the Armorican quartzite facies in Central Spain. Middle Arenig faunas include two palaeotaxodont forms (Praenucula oehlerti and Cardiolaria sp.), and two different palaeoheterodonts (Modiolopsis sp. and ?Actinodontoida indet.). Previous reports of other Arenig bivalves, especially actinodontoids, from coeval quartzites of northwestern, Central and northeastern Spain, as well as from Central Portugal, have been also briefly examined. The Iberian faunas show close affinities with the well known Arenig assemblages from the "Gres armoricain" of Western France, and add new data for the scenic reconstruction of the Lower Ordovician bivalve radiations on the northwestern Condwanan shelves.Este trabajo es una contribución a los proyectos 351 (Paleozoico Inferior del NO de Gondwana) y 410 (El gran evento de biodiversificación ordovícico) del PICG (IUGS-UNESCO).Peer reviewe