Caviomorpha is the

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 ...

infraorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

parvorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

that unites all New World

hystricognath The Hystricognathi are an infraorder of rodents, distinguished from other rodents by the bone structure of their skulls. The masseter medialis (a jaw muscle) passes partially through a hole below each eye socket (called the infraorbital foramen) ...

s. It is supported by both

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 ...

and

molecular A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...

evidence. The Caviomorpha was for a time considered to be a separate order outside the Rodentia, but is now accepted as a genuine part of the rodents. Caviomorphs include the extinct Heptaxodontidae (giant hutias) and extant families of chinchilla rats,

hutias Hutias (known in Spanish as jutía) are moderately large cavy-like rodents of the subfamily Capromyinae that inhabit the Caribbean islands, with most species restricted to Cuba and Hispaniola. Twenty species of hutia have been identified, but at ...

guinea pig The guinea pig or domestic guinea pig (''Cavia porcellus''), also known as the cavy or domestic cavy (), is a species of rodent belonging to the genus '' Cavia'' in the family Caviidae. Breeders tend to use the word ''cavy'' to describe the ...

s and the

capybara The capybaraAlso called capivara (in Brazil), capiguara (in Bolivia), chigüire, chigüiro, or fercho (in Colombia and Venezuela), carpincho (in Argentina, Paraguay and Uruguay) and ronsoco (in Peru). or greater capybara (''Hydrochoerus hydro ...

chinchilla Chinchillas are either of two species ('' Chinchilla chinchilla'' and '' Chinchilla lanigera'') of crepuscular rodents of the parvorder Caviomorpha. They are slightly larger and more robust than ground squirrels, and are native to the Andes m ...

s and

viscacha Viscacha or vizcacha (, ) are rodents of two genera ('' Lagidium'' and '' Lagostomus'') in the family Chinchillidae. They are native to South America and convergently resemble rabbits. The five extant species of viscacha are: *The plains v ...

tuco-tuco A tuco-tuco is a neotropical rodent in the family Ctenomyidae.Parada, A., G. D’Elia, C.J. Bidau, and E.P. Lessa. 2011. Species Groups and the Evolutionary Diversification of Tuco-Tucos, genus ''Ctenomys'' (Rodentia: Ctenomyidae). ''Journal of M ...

agoutis The agouti (, ) or common agouti is any of several rodent species of the genus ''Dasyprocta''. They are native to Middle America, northern and central South America, and the southern Lesser Antilles. Some species have also been introduced else ...

, pacas, pacaranas, spiny rats, New World porcupines,

coypu The nutria (''Myocastor coypus''), also known as the coypu, is a large, herbivorous, semiaquatic rodent. Classified for a long time as the only member of the family Myocastoridae, ''Myocastor'' is now included within Echimyidae, the family of ...

and octodonts (Vassallo and Antenucci, 2015).

Origin

The first known rodent

fossils 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 ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the souther ...

are represented by the three taxa ''Cachiyacuy contamanensis'', ''C. kummeli'', and ''Canaanimys maquiensis'', as well as teeth from ''Eobranisamys'' sp. (Dasyproctidae) and ''Eospina'' sp., the latter two found also in the Santa Rosa fauna from the late

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

or early

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but ...

. By the late

, all superfamilies and most families of caviomorphs are present in the fossil record. During this time, South America was isolated from all other

continent A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven ...

s. Several hypotheses have been proposed as to how hystricognath rodents colonized this island continent. Most require that a small group of these rodents traveled across ocean bodies atop a

raft A raft is any flat structure for support or transportation over water. It is usually of basic design, characterized by the absence of a hull. Rafts are usually kept afloat by using any combination of buoyant materials such as wood, sealed barrel ...

mangrove A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in several ...

s or

driftwood __NOTOC__ Driftwood is wood that has been washed onto a shore or beach of a sea, lake, or river by the action of winds, tides or waves. In some waterfront areas, driftwood is a major nuisance. However, the driftwood provides shelter and fo ...

. The most common hypothesis suggests that the ancestor to all modern caviomorphs rafted across the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth#Surface, Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Afr ...

(then narrower) from

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

(Lavocat, 1969; Huchon and Douzery, 2000). This is supported by molecular results, which suggest that the Phiomorpha (as restricted to Bathyergidae,

Petromuridae Petromuridae is a family of hystricognath rodents that contains the dassie rat ''(Petromus typicus)'' of southwestern Africa, the only extant member of this group. The genus ''Petromus ''Petromus'' is a genus of hystricognath rodents ...

, and

Thryonomyidae Thryonomyidae is a family of hystricognath rodents that contains the cane rats ''(Thryomys)'' found throughout sub-Saharan Africa, and a number of fossil genera. Taxonomy Thryonomyidae was formerly more diverse and widespread, with fossil relat ...

) are sister taxa to the Caviomorpha. In fact, until the discovery of the

Laotian rock rat The Laotian rock rat or ''kha-nyou'' (''Laonastes aenigmamus'', Lao: ຂະຍຸ), sometimes called the "rat-squirrel", is a species of rodent found in the Khammouan region of Laos. The species was first described in a 2005 article by Paulina ...

, all modern hystricognath families were restricted to South America, Africa, or had a range that included Africa ( Hystricidae).

New World monkey New World monkeys are the five families of primates that are found in the tropical regions of Mexico, Central and South America: Callitrichidae, Cebidae, Aotidae, Pitheciidae, and Atelidae. The five families are ranked together as the Ceboid ...

s appear to have colonized South America from Africa at a similar time. Caviomorphs went on to colonize the

West Indies The West Indies is a subregion of North America, surrounded by the North Atlantic Ocean and the Caribbean Sea that includes 13 independent island countries and 18 dependencies and other territories in three major archipelagos: the Great ...

as far as the

Bahamas The Bahamas (), officially the Commonwealth of The Bahamas, is an island country within the Lucayan Archipelago of the West Indies in the North Atlantic. It takes up 97% of the Lucayan Archipelago's land area and is home to 88% of the archi ...

, reaching the Greater Antilles by the early Oligocene. This is commonly viewed as another example of oceanic dispersal, although a role for a possible land bridge has also been considered.

Diversity

Caviomorph rodents underwent an explosive diversification upon arrival into South America. They managed to outcompete other animals in rodent-like niches such as certain South American marsupials. Retaining predominantly

herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

diets, they expanded their sizes to encompass a range from rat-sized echimyids to the

bison Bison are large bovines in the genus ''Bison'' (Greek: "wild ox" (bison)) within the tribe Bovini. Two extant and numerous extinct species are recognised. Of the two surviving species, the American bison, ''B. bison'', found only in North ...

-sized '' Phoberomys''. Their ecologies included burrowing

gopher Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 speciesSearch results for "Geomyidae" on thASM Mammal Diversity Database are all endemic to North and Central America. They ar ...

-like forms such as

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose num ...

forms such as porcupines and certain spiny rats, running forms such as

mara Mara or MARA may refer to: Animals * Mara (mammal), a species of the cavy family *Mara the Lioness, in the movie ''Born Free'' Arts and entertainment Fictional characters * Mara (''Doctor Who''), an evil being in two ''Doctor Who'' serials *Mara, ...

s, and aquatic forms such as the

and

nutria The nutria (''Myocastor coypus''), also known as the coypu, is a large, herbivorous, semiaquatic rodent. Classified for a long time as the only member of the family Myocastoridae, ''Myocastor'' is now included within Echimyidae, the family of ...

(Vassallo and Antenucci, 2015). Habitats include grasslands (maras), high mountains ( chinchillas and chinchilla rats), forest edges ( prehensile-tailed porcupines) and dense tropical forests (

paca A paca is a member of the genus ''Cuniculus'' of ground-dwelling, herbivorous rodents in South and Central America. It is the only genus in the family Cuniculidae. Pacas are large rodents with dots and stripes on their sides, short ears, ...

s and acouchis). Although many species of caviomorphs have migrated into

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

since the

Great American Interchange The Great American Biotic Interchange (commonly abbreviated as GABI), also known as the Great American Interchange and the Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic biotic interchange event in which la ...

, only a single living species, the

North American porcupine The North American porcupine (''Erethizon dorsatum''), also known as the Canadian porcupine, is a large quill-covered rodent in the New World porcupine family. It is the second largest rodent in North America, after the North American beaver ('' ...

, has naturally colonized North America north of Mexico (the extinct capybara '' Neochoerus pinckneyi'' also accomplished this feat). The

has been introduced into North America and has proven a highly successful

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adv ...

there.

Families

*Parvorder Caviomorpha - New World hystricognaths **†'' Luribayomys'' - ''

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertain ...

'' **Superfamily Cavioidea *** Caviidae - cavies,

s, and maras *** Ctenomyidae - tuco-tucos *** Cuniculidae - pacas ***

Dasyproctidae Dasyproctidae is a family of large South American rodents, comprising the agoutis and acouchis. Their fur is a reddish or dark colour above, with a paler underside. They are herbivorous, often feeding on ripe fruit that falls from trees. They li ...

- agoutis and acouchis *** Dinomyidae - pacarana ***† Eocardiidae ***†''

Guiomys ''Guiomys'' is an extinct genus of cavioid rodent which lived in west central Patagonia of Argentina (Collón Curá Formation), Bolivia (Honda Group) and Peru ( Yahuarango Formation) during the Middle Miocene ( Laventan).

'' ***† Neoepiblemidae ***†'' Scotamys'' **Superfamily

Chinchilloidea Caviomorpha is the rodent infraorder or parvorder that unites all New World hystricognaths. It is supported by both fossil and molecular evidence. The Caviomorpha was for a time considered to be a separate order outside the Rodentia, but is now ...

*** Abrocomidae - chinchilla rats ***†'' Borikenomys'' - ''incertae sedis'' *** Chinchillidae - chinchillas and viscachas ***† Heptaxodontidae - giant hutias ***†'' Maquiamys'' - ''incertae sedis'' ***†'' Tsaphanomys'' - ''incertae sedis'' ** Superfamily Erethizontoidea ***Family Erethizontidae - New World porcupines **Superfamily

Octodontoidea Caviomorpha is the rodent infraorder or parvorder that unites all New World hystricognaths. It is supported by both fossil and molecular evidence. The Caviomorpha was for a time considered to be a separate order outside the Rodentia, but is ...

***†'' Caviocricetus'' - ''incertae sedis'' ***†'' Dicolpomys'' - ''incertae sedis'' ***

Echimyidae Echimyidae is the family of neotropical spiny rats and their fossil relatives. This is the most species-rich family of hystricognath rodents. It is probably also the most ecologically diverse, with members ranging from fully arboreal to ter ...

- spiny rats, coypus, and hutias ***†'' Morenella'' - ''incertae sedis'' ***

Octodontidae Octodontidae is a family of rodents, restricted to southwestern South America. Fourteen species of octodontid are recognised, arranged in seven genera. The best known species is the common degu, ''Octodon degus''. Octodontids are medium-sized ...

- degus and relatives ***†'' Plateomys'' - ''incertae sedis'' ***†'' Tainotherium'' Turvey, Grady & Rye, 2006 - ''incertae sedis'' Note that some changes to this taxonomy have been suggested by

studies. The Dinomyidae is now thought to belong to the Chinchilloidea rather than the Cavioidea, the Abrocomidae may belong to the Octodontoidea, and the Hydrochaeridae may have evolved from within the Caviidae.

References

Citations

Sources

* Huchon, D. E. J. P. Douzery. 2001. "From the Old World to the New World: A molecular chronicle of the phylogeny and biogeography of hystricognath rodents". Molecular Phylogenetics and Evolution, 20:238-251. * Jenkins, P. D., C. W. Kilpatrick, M. F. Robinson, and R. J. Timmins. 2004. "Morphological and molecular investigations of a new family, genus and species of rodent (Mammalia: Rodentia: Hystricognatha) from Lao PDR". Systematics and Biodiversity, 2:419-454. * Lavocat, R. 1969. "La systématique des rongeurs hystricomorphes et la dérive des continents". C. R. Acad. Sci. Paris Sér. D., 269:1496-1497. * Marivaux, L. M. Vianey-Liaud, and J.-J. Jaeger. 2004. "High-level phylogeny of early Tertiary rodents: dental evidence". Zoological Journal of the Linnean Society, 142:105-134. * McKenna, Malcolm C., and Bell, Susan K. 1997. ''Classification of Mammals Above the Species Level.'' Columbia University Press, New York, 631 pp. * Opazo, J. C. 2005
A molecular timescale for Caviomorph rodents (Mammalia, Hystricognathi)
"Molecular Phylogenetics and Evolution", 37:932-937. * Vassallo, A. I., and C. D. Antenucci. 2015. Biology of Caviomorph Rodents: Diversity and Evolution. Sociedad Argentina para el Estudio de los Mamíferos (SAREM) Series A Mammalogical Research. * Wood, A. E. 1985. The relationships, origin, and dispersal of hystricognath rodents. pp 475–513 in ''Evolutionary relationships among rodents, a multidisciplinary approach'' (W. P. Luckett and J.-R. Hartenberger, eds.). Plenum Press, New York.

Origin

Diversity

Families

References

Citations

Sources

See also