Synopsis

The Middle Callovian/Oxfordian/Early Kimmeridgian Staffin Shale Formation at Staffin Bay, Isle of Skye contains one of the most complete, fossiliferous successions through Oxfordian strata in Britain, with Cordatum Zone (Chronozone) strata very well developed. During several visits to Staffin over the last 40 years, the author has collected some eighty ammonites from the Cordatum Zone. Well-preserved cardioceratid ammonites are common in the Costicardia Subzone of the Cordatum Zone, and these are the subject of the present study. Cordatum Subzone ammonites are less common and less well preserved at Staffin and, consequently, more problematic for such detailed study. Detailed analysis of Cordatum Zone cardioceratids as a whole shows that it is likely that almost all these Costicardia Subzone cardioceratinids belonged to the one species Cardioceras costicardia biosp.; all other morphospecies of Cardioceras recognized by previous authors from this subzone are regarded here as varieties of C. costicardia biosp. Goliathiceras, however, is regarded here as a separate Lower Oxfordian cardioceratid genus.

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