Orthoceras annulatum, Print, Orthoceras ("straight horn") is a genus of extinct nautiloid cephalopod restricted to Middle Ordovician-aged marine limestones of the Baltic States and Sweden. This genus is sometimes called Orthoceratites.
Orthoceras annulatum, Print, Orthoceras ("straight horn") is a genus of extinct nautiloid cephalopod restricted to Middle Ordovician-aged marine limestones of the Baltic States and Sweden. This genus is sometimes called Orthoceratites.