A MULTI-TAXIC EVALUATION OF THE QUALITY OF THE FOSSIL RECORD BASED ON MARINE BENTHIC ASSOCIATIONS OF COASTAL NORTH CAROLINA (Invited Presentation)

Many quantitative studies of the fossil record rely on using heavily biomineralized (i.e., highly preservable) species as a proxy for all species that may have been present originally. Paleontologists have been pursuing multiple approaches for evaluating this critical assumption. Here, building on a classic study of T. Schopf (1978), we attempt to quantify the potential quality of the fossil record using macrobenthic communities of coastal North Carolina.

In this progress report, we analyzed 70 bulk samples of live-collected macrobenthos collected across coastal habitats of North Carolina. All specimens were identified to the finest possible taxonomic level (typically species) and each taxon was categorized in terms of its latent fossilization potential, from the least (soft-tissue organisms) to most (species with heavily biomineralized skeletons) preservable. In an average sample, 54.8% of species and 54.5% of specimens belonged to highly preservable taxa. However, estimates for individual samples varied from <10% to >90%, for both species and specimen counts, even when small samples were removed. Thus, when considered in absolute numerical terms, preservable taxa may be a poor proxy for estimating diversity and abundance of all organisms that were originally present. However, sample-level estimates derived for preservable taxa correlated strongly with estimates based on all taxa.

These preliminary results suggest that preservable taxa may be an excellent proxy for tracking relative patterns of all taxa. This is a promising outcome when considering that paleontologists typically study relative patterns (e.g., changes in diversity through time) and have little interest in estimating correctly absolute values (e.g., the actual number of species that existed in a given time bin). Thus, the empirical case study presented here supports the contention that highly preservable taxa are a meaningful proxy useful in quantitative studies of the fossil record.