Remarks on older Ordovician Chitinozoa and biostratigraphy of the Oslo Region, southern Norway

Lower Sandbian (lower Caradoc) and older Ordovician chitinozoans from the Oslo Region, southern Norway, are discussed. Diagnostic Baltoscandian chitinozoan faunas have been found in the Bjørkåsholmen (upper Tremadocian), Huk (Lysaker and Herram Members, uppermost Stage 3–lowermost Darriwilian), Elnes (Håkavik Member, upper Darriwilian), and Vollen (uppermost Darriwilian–lower Sandbian) formations. One species of biostratigraphic importance, Hercochitina aff. spinetum, from the Arnestad Formation (upper Sandbian, lower Caradoc) in the Oslo-Asker district, is descibed from Baltoscandia for the first time.