Cyrtobaltoceras is an extinct cephalopod genus known from the upper Lower Ordovician Fort Cassin Formation at Valcour, N.Y. that is included in the Nautiloid...

†Amsleroceras †Annbactroceras †Bactroceras †Castelloceras †Cochlioceras †Cyrtobaltoceras †Endorioceras †Eosomichelinoceras †Hedstroemoceras †Metabaltoceras...

Cochlioceras Copiceras Clelandoceras Cumberloceras Cyclostomiceras Cyrtobaltoceras Desioceras Diaphoroceras Diastoloceras Dwightoceras Dyscritoceras Ectocycloceras...

†Cyclostomiceras †Cymatoceras †Cymatonautilus †Cyrtactinoceras †Cyrthoceratites †Cyrtobaltoceras †Cyrtoceras †Cyrtoceratites †Cyrtocerina †Cyrtocheilus †Cyrtogomphoceras...

†Cyptendoceras ruedemanni †Cyrtactinoceras †Cyrtactinoceras boycii †Cyrtobaltoceras †Cyrtobaltoceras gracile †Dactylagonia †Dactylagonia incrasata †Dactylogonia...

†Cybele †Cyclonema †Cyphaspis †Cypricardinia †Cypricardinia indenta †Cyrtobaltoceras †Cyrtoceras †Cyrtolites †Cyrtospirifer †Cyrtospirifer hornellensis...

unidentified comparable form †Cyrtinoides †Cyrtinoides eliei †Cyrtobaltoceras †Cyrtobaltoceras gracile †Cyrtoceras †Cyrtoceras eugenium †Cyrtoceras kirkbyi...