''Rhagamys'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

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 lower jaws. About 40% of all mammal species are roden ...

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 ex ...

, the Old World mice and rats. The genus was established by the Swiss zoologist

Charles Immanuel Forsyth Major Charles Immanuel Forsyth Major (15 August 1843, Glasgow – 25 March 1923, Munich) was a Scottish-born, Swiss physician, zoologist and vertebrate palaeontologist. Major was born in Glasgow and studied at Basel and Zurich Universities in Switz ...

to accommodate ''Rhagamys orthodon'', commonly known as Hensel's field mouse or the Tyrrhenian field rat, which is the only species in the genus. It was

endemic Endemism is the state of a species being found 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 found els ...

to the Mediterranean islands of Corsica and

Sardinia Sardinia ( ; it, Sardegna, label= Italian, Corsican and Tabarchino ; sc, Sardigna , sdc, Sardhigna; french: Sardaigne; sdn, Saldigna; ca, Sardenya, label= Algherese and Catalan) is the second-largest island in the Mediterranean Sea, af ...

, where it first appeared in the

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 ...

record in the

Late Pleistocene The Late Pleistocene is an unofficial age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a stratigraphic perspective. It is intended to be the fourth division of the Pleistocene Epoch within ...

, and was relatively large in size, weighing up to 50 g. Its closest living relatives are of the genus ''

Apodemus ''Apodemus'' is a genus of Muridae (true mice and rats). The name is unrelated to that of the ''Mus'' genus, instead being derived from the Greek ἀπό-δημος (literally ''away from home''). Taxonomy Related to the Ryūkyū spiny rats ...

''.

Taxonomy and evolution

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

Late Pliocene Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effe ...

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 teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...

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

wood mouse The wood mouse (''Apodemus sylvaticus'') is a 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 neck, ...

(''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), ''Apode ...

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

hypsodont Hypsodont is a pattern of dentition with high-crowned teeth and enamel extending past the gum line, providing extra material for wear and tear. Some examples of animals with hypsodont dentition are cows and horses; all animals that feed on grit ...

teeth suitable for feeding on a coarse, abrasive diet. Over time, ''Rhagamys orthodon'' increased in size and became larger than the broad-toothed field mouse (''Apodemus mystacinus'').

History

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'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks and ...

(''

Mammuthus lamarmorai ''Mammuthus lamarmorai'' is a species of mammoth which lived during the late Middle and Upper Pleistocene (between 450,000 and perhaps 40,000 years) on the island of Sardinia. ''M. lamarmorai'' is a dwarf species, as it is estimated to have rea ...

''), the Tyrrhenian vole ('' Microtus henseli''), the Sardinian pika ('' Prolagus sardus''), one or two species of shrew belonging to the genus '' Asoriculus'', a

mole Mole (or Molé) may refer to: Animals * Mole (animal) or "true mole", mammals in the family Talpidae, found in Eurasia and North America * Golden moles, southern African mammals in the family Chrysochloridae, similar to but unrelated to Talpida ...

('' Talpa tyrrhenica''), the

Sardinian dhole The Sardinian dhole (''Cynotherium sardous'') is an extinct insular canid which was endemic to what is now the Mediterranean islands of Sardinia (Italy) and Corsica (France), which were joined for much of the Pleistocene. It went extinct when h ...

(''Cynotherium sardous''), a galictine

mustelid The Mustelidae (; from Latin ''mustela'', weasel) are a family of carnivorous mammals, including weasels, badgers, otters, ferrets, martens, minks and wolverines, among others. Mustelids () are a diverse group and form the largest family in t ...

('' Enhydrictis galictoides''), three species of otter ('' Algarolutra majori, Sardolutra ichnusae,

Megalenhydris barbaricina ''Megalenhydris barbaricina'' is a Late Pleistocene giant otter from Sardinia. It is known from a single skeleton, discovered in the ''Grotta di Ispinigoli'' near Dorgali, and was described in 1987. The species is one of four extinct otter specie ...

'') and a

deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the ...

(''

Praemegaceros cazioti ''Praemegaceros'' is an extinct genus of deer, known from the Pleistocene and Holocene of Western Eurasia. It contains the subgenera ''Praemegaceros,'' ''Orthogonoceros'' and ''Nesoleipoceros''. It has sometimes been synonymised with ''Megaloce ...

''). The small mammals, including ''Rhagamys'', persisted for many thousands of years after the first human arrival on the islands, with the youngest radiocarbon dates for ''Rhagamys'' dating to around 800 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 (''Plecotus sardus'').

References

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