Cardioceras excavatoides ammonite fossils collected from Jurassic, Oxfordonian sediments on the Western Isles of Scotland. Cardioceras are a genus of ammonite which existed during the Oxfordinian stage of the Jurassic approximately 154 to 146 Mya. They were nektonic carnivores and upon death their shells fell to the sea floor. These specimens exhibit fine sinuous ribs with a prominent keel. Specimens vary in size between 1 and 3 cm in diameter but most measure approximately 1 cm as Cardioceras rarely grew above 2.5 cm in diameter. Supplied in small plastic bags with an information label.