Eubrachyura is a group of
decapodcrustaceans (
ranked as a "section") comprising the more derived
crabs. It is divided into two subsections, based on the position of the genital openings in the two sexes. In the
Heterotremata, the openings are on the
legs in the males, but on the
sternum in females, while in the
Thoracotremata, the openings are on the sternum in both sexes. This contrasts with the situation in other
decapods, in which the genital openings are always on the legs. Heterotremata is the larger of the two groups, containing the species-rich superfamilies
Xanthoidea and
Pilumnoidea and all the
freshwater crabs (
Gecarcinucoidea,
Potamoidea). The eubrachyura is well known for actively and constantly building its own burrows.[2] The
fossil record of the Eubrachyura extends back to the
Cretaceous;[3] the supposed
Bathonian (
Middle Jurassic) representative of the group, Hebertides jurassica,[4] ultimately turned out to be
Cenozoic in age.[5]
^Danièle Guinot; Antonio de Angeli; Alessandro Garassino (2007). "Hebertides jurassica n. gen., n. sp. (Crustacea, Decapoda, Brachyura) from the Middle Jurassic (Bathonian) of Normandy (France)". Atti della Società italiana di scienze naturali e del museo civico di storia naturale di Milano. 148 (2): 241–260.