Clitambonitoid brachiopods from the Middle and Upper Ordovician of the Oslo Region, Norway

Nine species of clitambonitoid brachiopods have been described from the Mid dle and Upper Ordovician of the Oslo Region. Norway. They include, Hemipron ites? sp., Clitambanites schmidti, Clinambon anomalus. Ilmarinia dimorpha, Vellamo oandoensis, Kullervo hibernica, Kullervo aff. parva. Kullervo aff. punctata and Kullarvo cf. lacunata. The palaeobiogeography and palaeoecolog y of the Upper Ordovician clitambonitoid brachiopods are discussed. The spe cies Found in the northern and western parts of the Oslo Region are mostly related to those of the Baltic carbonate platform, despite surprisingly lar ge differences in lithology. The foreland basin (the Oslo-Scania confacies belt of Jaanusson & Bergstrom, 1980) has a different fauna, dominated by pa ndemic species of Kullervo. This genus is supposed to have developed in par allel in Avalonia (pandemic species and the North American species) and Bal tica tall endemic species to Baltica), from an early kullervo of either Bal tic or Avalonian origin. The rapid spread of the genus in the North Atlanti c area is linked - in time - to the large bentonite in the Middle Caradocia n.