ORDOVICIAN DIVERSIFICATION DYNAMICS OF TROPHIC AND TAXONOMIC GROUPS

The rapid increase of genus richness during the Great Ordovician Biodiversification Event (GOBE) has been reported from many different taxonomic groups and from different geographic regions, although the richness peaks may not be simultaneous. Servais et al. (Palaeogeography, Palaeoclimatology, Palaeoecology 2010) suggested that the increases in both suspension feeders and pelagic carnivores contributed to major changes in food-web complexity during the GOBE. Since more than one mode of feeding may occur within one taxonomic group, e.g. trilobites can be carnivores or suspension-feeders, diversification dynamics amongst feeding versus taxonomic groups may reveal differences that give us insight into the GOBE.

I use data from The Paleobiology Database (PBDB) to estimate diversification dynamics by applying capture-recapture approaches to different trophic groups (suspension-feeders, deposit feeders, detrivores and carnivores) as well as major taxonomic groups (trilobites, brachiopods, cephalopods). If the resolution of the available data is fine enough, I expect to find origination rates of predator-groups (i.e. carnivores) and extinction rates of prey-groups (i.e. non-carnivores) to be temporally coordinated. I also expect the different taxonomic groups to be coordinated with respect to the timing of their greatest diversification rates during the GOBE if there is a strong signal of a global driver affecting the Ordovician fauna.