Phylogenetic analysis of most species within Necrocarcinoidea based upon 55 adult morphological characters supports the inclusion of 5 families within the superfamily. Two new genera are recognized within Necrocarcinidae, Arcticocarcinus n. gen. and Elektrocarcinus n. gen., and numerous new combinations have resulted. Necrocarcinoidea exhibited diversity peaks in the Albian (Early Cretaceous) and Campanian (Late Cretaceous), and displayed niche partitioning at the family level. Most Paleogene occurrences of Necrocarcinoidea are in carbonate rocks of Northern Europe.