Systematic Overview of the Molluscs and Barnacles of the Quaternary Breiðavík Group North Iceland

This chapter deals with the systematic aspects of the molluscan and barnacle assemblages found in the Breiðavik Group in North Iceland. They are primarily based on collections and field work carried out more or less each year since 1972. They are also based on the collections of the Institute of Natural History (Museum) in Reykjavik, the Geological Museum in Copenhagen, the collection of the farmer Johannes Bjornsson in Ytri-Tunga on Tjornes, and the collection of Mar Vilhjalmsson in Icelandic Institute of Natural History. We report 14 species of prosobranch gastropods, 2 opisthobranch gastropod species, 29 species of bivalves, and 2 species of barnacles have been identified from the Breiðavik Group. In total, it is a question of 45 species of molluscs and 2 barnacle species. Two of the mollusc species are new for the Breiðavik Group. Each species is illustrated on plates, and variation in shape is demonstrated where the material makes it possible. The distribution, recent or fossil, of the various species is recorded, and pertinent ecological and biological features are discussed. The larval development of the species is also recorded as their ability to migrate is significantly depending on the pelagic larval development. The Early Pleistocene Breiðavik fauna marks the transition of the warm temperate Tjornes faunas to the subarctic-arctic faunas at the onset of the Pleistocene.