Late Cretaceous swimming crabs: radiation, migration, competition, and extinction

Abstract

Intensive bed-by-bed collecting in the type Maastrichtian area over the past ten years revealed important new paleobiological data on the swimming crabs in the Late Cretaceous. The extinction of the family Carcinoeretidae at the K/T boundary seems to correpond to an exposive radiation and migration event of the better adapted family Xanthidae. All presently known morphological adaptations of the brachyuran carapace to a nektonic mode of life were already present in the Maastrichtian. A new xanthid crab of the type Maastrichtian area, Xanthosia delicata sp.n., is described and the understanding of the genus Cretachlorodius Fraaye, 1996, is discussed and extended.