Were decapod crustaceans affected by the Cretaceous-Paleogene mass extinction?

The Cretaceous-Paleogene (K-Pg) extinction is one of the most severe mass extinctions in Earth’s history linked to a meteorite impact near Chicxulub in Mexico and Deccan Trap volcanism in India. Many major groups became extinct (ammonites, belemnites, non-avian dinosaurs, etc.) or experienced major losses in their biodiversity (bivalves, insects, echinoids, etc.). Conversely, decapod crustaceans, major contributors to marine ecosystems since the Mesozoic Decapod Revolution, are thought to have experienced limited to no extinction based on global analyses. There are, however, multiple explanations for this apparent lack of extinction: (1) decapod diversity was indeed not affected much if at all by the K-Pg event, (2) there was a substantial loss in diversity, but taxon richness rebounded rapidly and was not detectable in global analyses, or (3) uneven sampling has distorted the true signal. Distinguishing between these scenarios has never been carried out thus far by controlled, quantitative sampling on either side of the K-Pg boundary locally at sites where both latest Cretaceous (Maastrichtian) and earliest Paleogene (Danian) decapod-bearing sediments are exposed. Previous research has attempted to assess a possible crustacean K-Pg extinction at a more regional scale, but sampling strategies were not provided and/or only very few decapod species were encountered on either side of the boundary insufficient for comparative analyses. We sampled extensively from two decapod-bearing sites, one in Alabama (USA) and one in Denmark. Collecting took place from sediments that are relatively comparable on both sides of the boundary (fine-grained siliciclastics in Alabama and limestones in Denmark). Specimens from museum collections from those sites augmented the new specimens collected during our recent fieldwork. After working out the taxonomy, we will assess possible changes in diversity, abundance, composition, and body size. The preliminary results will be presented during this conference.