Late Cretaceous-Early Palaeogene echinoderms and the K/T boundary in the southeast Netherlands and northeast Belgium — Part 5: Asteroids

tion. The palaeobiology of echinoderms occurring in the Meerssen and Geulhem members is discussed and changes in diversity across the K/T boundary are documented. Using literature data on the ecology of extant faunas, the various echinoderm groups are considered. Naturally, such data can only be applied with due caution to fossil forms, whose skeletal morphology is often incompletely known. This holds especially true for asteroids, ophiuroids, and crinoids, which, upon death, rapidly disinte-grate into jumbles of dissociated ossicles. Bioturbation, scavenging, and current winnowing all con-tribute to blurring the picture still further. However, data on extant forms do allow a preliminary sub-division of fossil species into various ecological groups, which are discussed herein. Combining recently published data on K/T boundary sections in Jylland and Sjælland (Denmark) with the pic-ture drawn here for the Maastricht area results in the following best constrained scenario. The demise of the highly diverse latest Maastrichtian echinoderm faunas, typical of shallow-water settings with local palaeorelief and associated unconsolidated bottoms, was rapid, suggestive of a catastrophic event (e.g. increased storm activity as a result of an asteroid impact). Following is the possible equiva-lent of the ‘dead zone ’ of the Danish sections, capped by the Vroenhoven hardground at the base o