Retroplumidae

Retroplumidae is a family of heterotrematan crabs, placed in their own (monotypic) superfamily, Retroplumoidea. Eight genera are recognised, of which all but two are only known from fossils: Ten species in two genera survive in the deep sea of the Indo-Pacific region: Fossil specimens ascribed to the Retroplumidae are known from the Late Cretaceous onwards, with Archaeopus antennatus in Coniacian–Maastrichtian rocks in California and Archaeopus ezoensis from Turonian–Maastrichtian rocks from Japan.