The Achelata is an infra-order of the decapod crustaceans, holding the spiny lobsters, slipper lobsters and their fossil relatives.
Anomura is a group of decapod crustaceans, including hermit crabs and others. Although the names of many anomurans include the word crab, all true crabs are in the sister group to the Anomura, the Brachyura.
Crangonidae is a family of shrimp, of the superfamily Crangonoidea, including the commercially important species Crangon crangon. Its type genus is Crangon. Crangonid shrimps' first pair of pereiopods have partially chelate claws that they use to capture their prey. They burrow shallowly into sediment on the sea floor, and feed on bivalves, crustaceans, polychaetes, and some small fish.
Cancridae is a family of crabs. It comprises six extant genera, and ten exclusively fossil genera, in two subfamilies:
Cancroidea is a superfamily of crabs, comprising the families Atelecyclidae and Cancridae. Four other families have been separated into new superfamilies: Cheiragonidae into Cheiragonoidea, Corystidae into Corystoidea, and both Pirimelidae and Thiidae into Portunoidea. Montezumellidae has been moved from Cancroidea to his own Superfamily Montezumelloidea Ossó & Domínguez, 2019.
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1976.
Carpilioidea is a superfamily of crabs containing a single extant family, Carpiliidae and three extinct families. The modern range of the family includes the Indo-Pacific, Western Atlantic and Caribbean Sea. The fossil record of the group extends back at least as far as the Paleocene.
The Aethridae are a family of crabs in their own superfamily, Aethroidea. It contains these genera :
Polychelida is an infraorder of decapod crustaceans. Fossil representatives are known dating from as far back as the Upper Triassic. A total of 38 extant species, all in the family Polychelidae, and 55 fossil species have been described.
Hexapodidae is a family of crabs, the only family in the superfamily Hexapodoidea. It has traditionally been treated as a subfamily of the family Goneplacidae, and was originally described as a subfamily of Pinnotheridae. Its members can be distinguished from all other true crabs by the reduction of the thorax, such that only seven sternites are exposed, and only four pairs of pereiopods are present. Not counting the enlarged pair of claws, this leaves only six walking legs, from which the type genus Hexapus, and therefore the whole family, takes its name. Some anomuran "crabs", such as porcelain crabs and king crabs also have only four visible pairs of legs. With the exception of Stevea williamsi, from Mexico, all the extant members are found either in the Indo-Pacific oceans, or around the coast of Africa.
Cheiragonidae is a small family of crabs, sometimes called helmet crabs, placed in its own superfamily, Cheriagonoidea. It comprises three extant species, Erimacrus isenbeckii, Telmessus acutidens and Telmessus cheiragonus, there are no yet evidences of Cheiragonidae in the fossil record. Many of these crabs were formerly treated as members of the Atelecyclidae.
Pilumnoidea is a superfamily of crabs, whose members were previously included in the Xanthoidea. The three families are unified by the free articulation of all the segments of the male crab's abdomen and by the form of the gonopods. The earliest fossils assigned to this group are of Eocene age.
Branchioplax is an extinct genus of crab which existed in Alaska and Washington during the Eocene period. It was first named by Mary Rathbun in 1916, and contains ten species, including Branchioplax washingtoniana from the Hoko River Formation, Branchioplax carmanahensis, and Branchioplax ballingi.
Aegeridae is a family of fossil prawns, one of the earliest Mesozoic shrimp families. It contains the genera Aeger, Acanthochirana, Anisaeger and Distaeger. The main diagnostic character of Aegeridae is the presence of numerous spines or thin setae on the third maxilliped.
Pseudozioidea is a superfamily of crabs, formerly treated in the Eriphioidea, Carpilioidea, Xanthoidea, Pilumnoidea and Goneplacoidea. A number of fossils from the Eocene onwards are known from the family Pseudoziidae. Eleven genera are recognised in three families:
Longichela orobica is an extinct species of prawn which lived in the Norian, and is the only species in the genus Longichela.
Bechleja is an extinct genus of shrimp which existed during the Eocene period. It contains four species.
Hepatus is a genus of crabs in the family Aethridae, containing seven extant species, plus some fossil species:
The Galatheoidea are a superfamily of decapod crustaceans comprising the porcelain crabs and some squat lobsters. Squat lobsters within the three families of the superfamily Chirostyloidea are not closely related to the squat lobsters within the Galatheoidea. The fossil record of the superfamily extends back to the Middle Jurassic genus Palaeomunidopsis.
Speocarcinus is a genus of crabs in the family Pseudorhombilidae, containing six extant species, one fossil species from the Late Miocene, one fossil species from the Eocene (Lutetian) and one fossil species from the Early Eocene (Ypresian):
