BIOMARKERS IN PALEOZOIC CRINOIDS (BORDEN GROUP, MISSISSIPPIAN): IMPLICATIONS FOR PHYLOGENY

Forty species of crinoids were uncovered in LeGrand, Iowa and fossils from this site became famous for their characteristic and peculiar species-specific coloration. Similar trends in color occur in the Borden Group (Mississippian) in Indiana, as well as other locations across North America and Europe, but the reasons behind these trends and the applications of this information have not been investigated. Inorganic pigments are usually the cause of unusual coloration in fossils, but in this case the species specific coloration is due to organic molecules, and is not a relic of taphonomic processes. Biomarker molecules are preserved and have been extracted from these Mississippian crinoids.

Fossil echinoderms, specifically crinoids, possess chromophoric organic molecules, fringelites, that resist diagenetic bleaching, are chemically stable over geologic time, and have occurrences and abundances that are species specific. When hue, chroma and saturation are determined for the colors of these fossils by comparison to a Munsel color chart, discriminant function analysis indicates that based on coloration, these crinoids sort into their morphologically determined Classes. Therefore, these fringelites and other related molecules, anthraquinones, are candidates to function as a proxy for phylogenetic reconstruction.

In this study, spectral data were defined for several extracts for several species of crinoids. Identifiable basal and radial plates were tested for biomarker molecules, and spectral data of the organic molecules present in the crinoids were obtained by UV-Vis, Fluorescence, HPLC (High Performance Liquid Chromatography), and GC/MS (Gas Chromatography / Mass Spectrometry). Preliminary results obtained by UV-Vis spectroscopy and Fluorometry indicate the presence of fringelites and anthraquinone: both are pigment molecules present in modern crinoids. Complex quinone molecules in the extracts are analyzed for their utility as trackable characters for phylogenetic analysis and are compared to the phylogeny of crinoids based on their morphology.

The goal for this research is to produce a biomarker index based on the presence and abundance of organic molecules in Paleozoic crinoids, and to use information from the preserved organic molecules as a proxy for phylogenetic reconstruction.