DETERMINING CONODONT DIVERSITY: RELATIONAL DATABASES, BAYESIAN HYPOTHESES OF SPECIES APPARATUSES, AND PHYLOGENETIC ANALYSIS

Estimates of Paleozoic metazoan preservation suggest that conodonts have one of the best fossil records. Systematic and paleobiological use of conodonts however, is limited since much taxonomy is based on single element types. Single element-taxonomy is often incongruent with the heteromorphic, multielement apparatuses of conodont species. The conodont record consists mainly of elements derived from post-mortem disassembly of apparatuses, and a true multielement taxonomy has relied on the rare discovery of complete apparatuses.This constrains our application of the conodont record to paleobiology, phylogenetics and biodiversity dynamics. This study enhances our understanding of conodont systematics and diversity with the construction of statistically testable hypotheses of multielement apparatuses from collections of dissociated elements. These hypotheses are, in effect, reconstructions of species morphologies.

Focusing on the U. Silurian-L. Devonian, we are compiling specimen-level information of element morphologies and occurrences, focusing on the genera Ancyrodelloides, Lanea, Lonchodina, Erika, Wurmiella, and Panderodus, into a relational database. Morphometric analysis and description of discrete characters organize variation within particular element types. Querying of the database yields data on the co-occurrence of element types and morphologies within temporally constrained samples. Single element co-occurrences are then used to construct hypotheses of multielement species apparatuses which are evaluated with a Bayesian calculation of posterior probabilities. Significantly supported hypotheses are used with natural multielement apparatuses as the basis for phylogenetic analysis of selected lineages. The resulting phylogenetic hypotheses will be used to describe patterns of origination and extinction during this interval. These patterns will be compared to the same taxa from Sepkoski's Compendium to evaluate the impact of an expanded multielement taxonomy.