''Metacarcinus starri'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

in the family

Cancridae Cancridae is a family of crabs. It comprises six extant genera, and ten exclusively fossil genera, in two subfamilies: Extant Genera Cancrinae Latreille, 1802 *'' Anatolikos'' Schweitzer & Feldmann, 2000 * ''Cancer'' Linnaeus, 1758 *''Glebocarci ...

, subfamily Cancrinae. The species is known solely from the

early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 Ma to 15.97 ± 0.05 Ma (million years ago). It was prece ...

, Clallam Formation and the underlying Pysht Formation deposits on the

Olympic Peninsula The Olympic Peninsula is a large arm of land in western Washington that lies across Puget Sound from Seattle, and contains Olympic National Park. It is bounded on the west by the Pacific Ocean, the north by the Strait of Juan de Fuca, and the ...

Washington state Washington (), officially the State of Washington, is a state in the Pacific Northwest region of the Western United States. Named for George Washington—the first U.S. president—the state was formed from the western part of the Washington ...

, United States.

History and classification

The species is known from only the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

female, number UWBM 92012, and five other specimens all of which are currently residing in the collections housed at the

Burke Museum of Natural History and Culture The Burke Museum of Natural History and Culture (Burke Museum) is a natural history museum in Seattle, Washington, in the United States. Established in 1899 as the Washington State Museum, it traces its origins to a high school naturalist club fo ...

Seattle, Washington Seattle ( ) is a port, seaport city on the West Coast of the United States. It is the county seat, seat of King County, Washington, King County, Washington (state), Washington. With a 2020 population of 737,015, it is the largest city in bo ...

, USA. The type specimens were first studied by Ross E. Berglund and James L. Goedert. Berglund and Goedert's

species description A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have be ...

was published in the ''

Journal of Paleontology The ''Journal of Paleontology'' is a peer-reviewed scientific journal covering the field of paleontology. It is published by the Paleontological Society. Indexing The ''Journal of Paleontology'' is indexed in: *BIOSIS Previews *Science Citatio ...

'' in 1996. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

"''starri''" was coined by the authors in recognition of David Starr, who collected and donated one of the

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). Of ...

specimens. When first described, ''M. starri'' was named ''Cancer (Metacarcinus) starri'' by Berglund and Goedert. In 1975, J. D. Nations had divided 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 b ...

'' into four subgenera, including ''Metacarcinus''. This placement was followed until 2000, when the subgenera were elevated to full genera by Carrie E. Schweitzer and Rodney M. Feldmann, Also available a
PDF
making the species' binomial ''Metacarcinus starri''.

Description

The oval

carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...

, nearly straight posterolateral margins, and

cheliped A chela ()also called a claw, nipper, or pinceris a pincer-like organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through New Latin '. The plural form is chelae. Legs bearing a chela are called chelipeds. ...

s with spiny upper margins are used as the basis for placing the species in ''Metacarcinus''. In comparisons of overall morphology, ''M. starri'' was noted to be most similar to the living species '' M. gracils'', commonly called the graceful rock crab. When published, ''M. starri'' was the oldest species of ''Metacarcinus'' to be described, being older than '' M. coosensis'', which is known from fossils found in Washington,

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

, and

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

. It is also the third species of ''Metacarcinus'' to be identified from Washington state fossils. The age and location indicate a possible Northern Pacific origin for the genus. ''Metacarcinus starri'' lived and was preserved in strata deposited at depths of , placing them in the lower

sublittoral zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated ...

. The specimens were preserved in

concretion A concretion is a hard, compact mass of matter formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. Concretions are often ovoid or spherical in shape, although irregular ...

s found as loose float cobbles along the

Strait of Juan de Fuca The Strait of Juan de Fuca (officially named Juan de Fuca Strait in Canada) is a body of water about long that is the Salish Sea's outlet to the Pacific Ocean. The international boundary between Canada and the United States runs down the centre ...

shoreline and collected at sites B6133 and B6136. However the individual cobble matrices match sediments found in the upper Pysht and lower Clallam Formations. This species lived with several other crustaceans, including the crab '' Pinnixa'' and a mud shrimp of the genus ''

Callianassa ''Callianassa'' is a genus of mud shrimps, in the family Callianassidae. Three of the species in this genus ('' C. candida'', '' C. tyrrhena'' and '' C. whitei'') have been split off into a new genus, '' Pestarella'', while others such as '' C ...

''. The extinct species '' Branchioplax washingtoniana'' was formerly though to also occur in the Clallam Formation with ''M. starri'', however with redefinition of the Twin River Group the sediments, ''B. washingtoniana'' has been shown to occur in the older Twin River Formation.

References

{{Taxonbar, from=Q6822377 Cancroidea Miocene crustaceans Crustaceans described in 1996 Fossil taxa described in 1996 Neogene arthropods of North America