Monoplacophora are rare fossils; only 15 specimens are known from the 4c-5b stratigraphic interval in Norway. Nevertheless, eight species assigned to five genera are recognized. All previously named species have been reillustrated and reassigned; one specific name is placed in synonymy. A new species of Patelliconus is named; this is the first report of the genus above the Middle Ordovician. Pygmaeoconus is questionably recognized in the Upper Ordovician for the first time, and a Norwegian Middle Ordovician species is assigned to it.
Monoplacophora(mollusca) from the Upper Ordovician of Norway