Orientation and anatomical notation in conodonts

All aspects of conodont paleontology rely on the identification and descrip tion of homologous anatomical units or elements. But the current schemes of anatomical notation and terms for orientation were formulated at a time wh en little was known of conodont anatomy or skeletal architecture, resulting in some confusion and difficulties in their application. With improving kn owledge of conodonts, these problems are becoming increasingly acute. In an attempt to address current problems, we introduce new terms for orien tation in conodonts and their elements, and a modified scheme of anatomical notation. The principal axes of the conodont body are identified as rostro caudal, dorsoventral, and mediolateral, with opposite lateral sides designa ted dextral and sinistral. Anatomical notation is defined according to topo logical relationships between elements with reference to the principal axes of the body and takes the form of letters with numeric subscripts (e.g., P -1, P-2, S-0-S-4). The ozarkodinid apparatus serves as a standard, but the P-n-S-n scheme can be applied rigorously to all taxa that are known from na tural assemblages or where an hypothesis of topological homology can be inf erred from secondary morphological criteria.