WHAT'S IN A NAME? CONODONT DIVERSITY DYNAMICS AND IMPORTANCE OF A STANDARDIZED TAXONOMIC NOMENCLATURE

Conodonts are a morphologically diverse, long-lived (Cambrian-Triassic), geographically widespread group of marine fossils. These characteristics make them ideal biostratigraphic markers in many time periods. Likewise, they are ripe for large-scale diversity dynamics studies and integrated diversity and integrated Earth systems studies. However, some barriers must be overcome to enable this work.

Conodont taxonomy remains a work in progress. Many clades of conodonts still have no known whole-apparatus assemblages from which to base a realistic multielement taxonomy. This problem must be solved by field work and collections-based work to better understand the possible morphological range of conodont apparatuses across the entire conodont fossil record. One of the major problems this unstable taxonomic system presents is the inability to produce meaningful diversity metrics for the clade.

A more tractable problem that would greatly improve our measures of conodont diversity is simply to standardize operational taxonomic units (OTUs) by eliminating sub-specific ranks. Workers in different time periods took different approaches to naming species vs sub-specific taxa (subspecies, morphospecies). Raising all sub-specific published taxa to the species rank would allow much more accurate assessments of species-level diversity changes across time period boundaries. It would also allow accurate counts of how many species are assigned to a genus or other higher taxonomic rank.

Standardizing sub-specific ranks to species would also help push the philosophy of conodont relationships toward a more cladistic worldview. Names affect how we as workers categorize and consider relationships among taxa. The proliferation of subspecies names is often based on gross morphological similarity (phenetics) or on hypothesized ancestor-descendent relationships that can be consistent with the fossil record but can never be proven. Raising sub-specific taxa to the species level and discouraging naming of new subspecies will help prompt workers to consider each taxon on its own merits, rather than in the context of a phylogenetically untested putative lineage.