Article: Nautiloids with multiple paired muscle scars from Lower–Middle Ordovician of Baltoscandia
The number, outline and arrangement of muscle scars on the internal mould of the body chamber of five species of Early and Middle Ordovician nautiloids from Baltoscandia are described. The ellesmeroceratids Oelandoceras haelluddenense Foerste and Pictetoceras oliviae King have 9-10 pairs of muscle scars. The oncoceratid Phtanoncoceras ellipticum (Lossen), and Botellusoceras torpense gen. et sp. nov., order and family indeterminate, have eight and nine pairs of muscle scars, respectively. The tarphycerid Estonioceras imperfectum (Quenstedt) has four pairs of muscle scars.