''Metacarcinus starri'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

crab Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek language, Greek), which typically have a very short projecting tail-like abdomen#Arthropoda, abdomen, usually hidden entirely under the Thorax (arthropo ...

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 *'' Glebocarc ...

, 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 (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

, Clallam Formation and the underlying

Pysht Formation The Pysht Formation is a Formation (geology), geologic formation in Washington (state). It preserves fossils dating back to the Paleogene Period (geology), period, which appear to have been deposited in an offshore marine environment. Outcrops are ...

deposits on the

Olympic Peninsula The Olympic Peninsula is a large peninsula 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 United States. It is often referred to as Washington State to distinguish it from the national capital, both named after George Washington ...

, United States.

History and classification

The species is known from only the

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

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 (commonly as Burke Museum) is a natural history museum on the campus of the University of Washington, in Seattle, Washington, United States. It is administered by the UW College of Arts and Scien ...

Seattle, Washington Seattle ( ) is the List of municipalities in Washington, most populous city in the U.S. state of Washington (state), Washington and in the Pacific Northwest region of North America. With a population of 780,995 in 2024, it is the List of Unit ...

, 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 scientific description of a newly encountered species, typically articulated through a scientific publication. Its purpose is to provide a clear description of a new species of organism and explain how it diff ...

was published in the ''

Journal of Paleontology The ''Journal of Paleontology'' is a peer-reviewed scientific journal covering the field of paleontology. It is managed and published by Cambridge University Press on behalf of the Paleontological Society. Indexing The ''Journal of Paleontology ...

'' in 1996. The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

"''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 (biology), isotype ...

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 Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...

'' 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 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 tortoises, the unde ...

, nearly straight posterolateral margins, and

cheliped A chela ()also called a claw, nipper, or pinceris a pincer-shaped organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through Neo-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 United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

, and

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. 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 and compact mass 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 shapes a ...

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 main outlet to the Pacific Ocean. The Canada–United States border, international boundary between Canada and the ...

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 '' Ca ...

''. The extinct species '' Branchioplax washingtoniana'' was formerly thought to also occur in the Clallam Formation with ''M. starri'', however with redefinition of the

Twin River Group Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of Twin Last Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two e ...

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