''Rhagamys'' 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 ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

s in the subfamily

Murinae The Old World rats and mice, part of the subfamily Murinae in the family Muridae, comprise at least 519 species. Members of this subfamily are called murines. In terms of species richness, this subfamily is larger than all mammal families excep ...

, the Old World mice and rats. The genus was established by the Swiss zoologist Charles Immanuel Forsyth Major to accommodate ''Rhagamys orthodon'', which is the only species in the genus. It was

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the Mediterranean islands of

Corsica Corsica ( , , ; ; ) is an island in the Mediterranean Sea and one of the Regions of France, 18 regions of France. It is the List of islands in the Mediterranean#By area, fourth-largest island in the Mediterranean and lies southeast of the Metro ...

and

Sardinia Sardinia ( ; ; ) is the Mediterranean islands#By area, second-largest island in the Mediterranean Sea, after Sicily, and one of the Regions of Italy, twenty regions of Italy. It is located west of the Italian Peninsula, north of Tunisia an ...

, descending from '' Rhagapodemus'', which had colonised the islands around 3.6 million years ago. Its closest living relatives are of the genus ''

Apodemus ''Apodemus'' is a genus of Muridae, murid (true mice and rats) containing the field mice as well as other well-known species like the wood mouse and the yellow-necked mouse. The name is unrelated to that of the ''Mus (genus), Mus'' genus, instead ...

,'' which includes the field and wood mice.

Taxonomy and evolution

The ancestors of ''Rhagamys'', belonging the widespread genus '' Rhagapodemus'', first arrived in Corsica-Sardinia during the Early-

Late Pliocene Late or LATE may refer to: Everyday usage * Tardy, or late, not being on time * Late (or the late) may refer to a person who is dead Music * Late (The 77s album), ''Late'' (The 77s album), 2000 * Late (Alvin Batiste album), 1993 * Late!, a pseudo ...

transition, around 3.6 million years ago. Three

chronospecies A chronospecies is a species derived from a sequential development pattern that involves continual and uniform changes from an extinct ancestral form on an evolutionary scale. The sequence of alterations eventually produces a population that is p ...

of the lineage have been named, including "''Rhagapodemus''" ''azzarolii'' from the earliest Late Pliocene, followed by "''Rhagapodemus''" ''minor'' from the Early Pleistocene, succeeded by ''Rhagamys orthodon'', which ranged from the Middle Pleistocene to Holocene. The

molars The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, '' ...

of ''Rhagamys'' are similar to those of the

wood mouse The wood mouse (''Apodemus sylvaticus'') is a Muridae, murid rodent native to Europe and northwestern Africa. It is closely related to the yellow-necked mouse (''Apodemus flavicollis'') but differs in that it has no band of yellow fur around the ...

(''Apodemus sylvaticus'') and the

striped field mouse The striped field mouse (''Apodemus agrarius'') is a rodent in the family Muridae. The range of this species stretches from Eastern Europe to Eastern Asia. Synonyms Accepted synonyms include ''Apodemus albostriatus'' (Bechstein, 1801), ''Apodemu ...

(''Apodemus agrarius'') but are larger and more derived, being

hypsodont Hypsodont is a pattern of dentition characterized by with high crowns, providing extra material for wear and tear. Some examples of animals with hypsodont dentition are cows and horses; all animals that feed on gritty, fibrous material. The oppos ...

teeth suitable for feeding on a coarse, abrasive diet. Over time, The ''Rhagapodemus''-''Rhagamys'' lineage increased in size, with ''Rhagamys orthodon'' having an estimated mass of approximately , two and a half times larger than its mainland ancestor, an example of island gigantism.

Paleoenvironment and extinction

Before the arrival of humans on the islands in about 8000 BC, Corsica and Sardinia had their own highly

depauperate terrestrial mammal fauna which besides ''Rhagamys orthodon'' included a species of dwarf

mammoth A mammoth is any species of the extinct elephantid genus ''Mammuthus.'' They lived from the late Miocene epoch (from around 6.2 million years ago) into the Holocene until about 4,000 years ago, with mammoth species at various times inhabi ...

('' Mammuthus lamarmorai''), the Tyrrhenian vole ('' Microtus henseli''), the Sardinian pika ('' Prolagus sardus''), the shrew '' Asoriculus similis'', a mole ('' Talpa tyrrhenica''), the Sardinian dhole (''Cynotherium sardous''), a galictine

mustelid The Mustelidae (; from Latin , weasel) are a diverse family of carnivoran mammals, including weasels, badgers, otters, polecats, martens, grisons, and wolverines. Otherwise known as mustelids (), they form the largest family in the suborde ...

('' Enhydrictis galictoides''), three species of

otter Otters are carnivorous mammals in the subfamily Lutrinae. The 13 extant otter species are all semiaquatic, aquatic, or marine. Lutrinae is a branch of the Mustelidae family, which includes weasels, badgers, mink, and wolverines, among ...

('' Algarolutra majori, Sardolutra ichnusae, Megalenhydris barbaricina'') and a

deer A deer (: deer) or true deer is a hoofed ruminant ungulate of the family Cervidae (informally the deer family). Cervidae is divided into subfamilies Cervinae (which includes, among others, muntjac, elk (wapiti), red deer, and fallow deer) ...

('' Praemegaceros cazioti''). The small mammals, including ''Rhagamys'', persisted for many thousands of years after the first human arrival on the islands, with the youngest radiocarbon date for ''Rhagamys'' on Sardinia being around 822-776 BC, while on Corsica the youngest dates for the species are around 393 BC. It was almost certainly extinct by the 6th century AD. The cause of the extinction is unknown, but may be due to invasive species introduced by new arrivals to the islands such as Carthaginians and the Romans. The only endemic mammal still found on the islands is the

Sardinian long-eared bat The Sardinian long-eared bat (''Plecotus sardus'') is a critically-endangered species of bat endemic to Sardinia, Italy. This species was discovered in 2002 in the caves of central Sardinia, the type locality being a cave in Lanaitto's Valley ...

(''Plecotus sardus'').

References

{{Taxonbar, from=Q10811507 Old World rats and mice Rodents of Europe Pleistocene rodents Rodent genera Taxa named by Charles Immanuel Forsyth Major Extinct rodents Mammals described in 1856 Fossil taxa described in 1856