Differentiation of Late Cambrian-Early Ordovician species of Cordylodus (Conodonta) with biapical basal cavities

Four species of the conodont genus Cordylodus are recognised, containing elements that have two apices in the basal cavity (biapical), one extending into the cusp and the other into the first denticle of the posterior process. They are C. prion Lindstrom 1955, C. lindstromi Druce & Jones 1971, C. prolinstromi sp. nov. and C. sp. nov. B. Cordylodus sp. nov. In all four species, the biapical cavity is best developed in the S elements, poorly developed in the P elements and, except in C. prion, absent in the M element. Multiple basal cavity apices that extend into the cusp and into the base of one or more denticles of the posterior process, may be found in aberrrant specimens of most species of Cordylodus, but the consistent presence of the biapical cavity seems to be limited to these four species of the genus.