''Metacarcinus'' is a genus of crabs formerly included in the genus ''

Cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bl ...

''. It includes nine exclusively

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

species and five extant species, of which four are also known from the fossil record. A molecular study using the

cytochrome oxidase I Cytochromes are redox-active proteins containing a heme, with a central Fe atom at its core, as a cofactor. They are involved in electron transport chain and redox catalysis. They are classified according to the type of heme and its mode of ...

gene does not support the

monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gr ...

of this genus.

Description

''Metacarcinus'' crabs have an oval carapace of about ⅔ of its largest width, with a surface with poorly marked division of smooth or gently colored regions. The front edge usually does not protrude before orbital, and the total length of these edges is 26–34% of the largest width of the carapace, with 5 spikes, including inner orbits, of which the middle springs lower than the others. 9–10 spikes are located on both anteroposterior lateral sides of the carapace; they can be of different shapes. The lateral edges are edged and can have one spike. The claws propodite is characterized by an upper edge at an angle of about 120° to the distal edge, equipped with sharp spines or grained or smooth keel. On the external surface of the propodite there are usually 4 balls. The cutting edges of the pliers' fingers of the claw have sharp teeth. The fixed finger has two points: middle and on the bottom edge.

Extant species

Included species: Also available a
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Fossils

*† ''

Metacarcinus danai ''Metacarcinus'' is a genus of crabs formerly included in the genus ''Cancer''. It includes nine exclusively fossil species and five extant species, of which four are also known from the fossil record. A molecular study using the cytochrome oxi ...

'' (Miocene, California) *† '' Metacarcinus davidi'' (Miocene to Pliocene, California) *† ''

Metacarcinus goederti ''Metacarcinus'' is a genus of crabs formerly included in the genus ''Cancer''. It includes nine exclusively fossil species and five extant species, of which four are also known from the fossil record. A molecular study using the cytochrome oxi ...

'' (Oligocene, Alaska) *† ''

Metacarcinus izumoensis ''Metacarcinus'' is a genus of crabs formerly included in the genus ''Cancer''. It includes nine exclusively fossil species and five extant species, of which four are also known from the fossil record. A molecular study using the cytochrome oxi ...

'' (Miocene, Japan) *† ''

Metacarcinus jenniferae ''Metacarcinus'' is a genus of crabs formerly included in the genus ''Cancer''. It includes nine exclusively fossil species and five extant species, of which four are also known from the fossil record. A molecular study using the cytochrome oxi ...

'' (Middle Pliocene, California) *† ''

Metacarcinus minutoserratus ''Metacarcinus'' is a genus of crabs formerly included in the genus ''Cancer''. It includes nine exclusively fossil species and five extant species, of which four are also known from the fossil record. A molecular study using the cytochrome oxi ...

'' (Pliocene, Japan) *† ''

Metacarcinus starri ''Metacarcinus starri'' is an extinct species of crab in the family Cancridae, subfamily Cancrinae. The species is known solely from the early Miocene, Clallam Formation and the underlying Pysht Formation deposits on the Olympic Peninsula of W ...

'' (Early Oligocene, Washington)

References

External links

* Cancroidea Decapod genera Extant Oligocene first appearances Taxa named by Alphonse Milne-Edwards {{crab-stub