The highly fossiliferous upper Darriwilian to lower Sandbian Elnes Formation of Norway presents an interesting insight into the general responses and preferences of Lower Palaeozoic faunas belonging to a stable, mud dominated middle to outer shelf environment in connection with a major transgressive to regressive system tract. The rich trilobite fauna consisting of nearly 100 taxa is closely linked to the changes in the environment, being most abundant in a muddy and siliciclastic dominated environment just above storm wave base. The fauna is highly endemic for the region and the remainder of Baltoscania. Trilobites of the Middle Ordovician Elnes Formation of the Oslo Region, Norway presents a taxonomic description of the total trilobite fauna, including a new genus and seven hitherto unknown species. New and extensive biostratigraphical data is presented on the trilobites together with a study on the biogeographical and ecological aspects of the faunas.
Thomas Hansen holds a postdoctoral position in palaeontology at the Institute for Geography and Geology, University of Copenhagen, Denmark. His main research interests have focused on Ordovician trilobite taxonomy and palaeoecology. He now works with Mesozoic and Caenozoic gastropods.