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 Mandible, lower jaws. About 40% of all mammal specie ...

parvorder that unites all New World hystricognaths. 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 preserve ...

and molecular 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), the extinct '' Josephoartigasia monesi'' (the largest rodent ever known) and extant families of chinchilla rats, hutias,

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'', family Caviidae. Animal fancy, Breeders tend to use the name "cavy" for the ani ...

s and the

capybara The capybara or greater capybara (''Hydrochoerus hydrochaeris'') is the largest living rodent, native to South America. It is a member of the genus '' Hydrochoerus''. The only other extant member is the lesser capybara (''Hydrochoerus isthmi ...

, chinchillas and viscachas, tuco-tucos, agoutis, pacas, pacaranas, spiny rats, New World porcupines, coypu 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 considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

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

or early

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

. 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 geographical regions. Continents are generally identified by convention (norm), convention rather than any strict criteria. A continent could be a single large landmass, a part of a very large landmass, as ...

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 barre ...

mangrove A mangrove is a shrub or tree that grows mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...

s or driftwood. 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 borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

(then narrower) from

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

(Lavocat, 1969; Huchon and Douzery, 2000). This is supported by molecular results, which suggest that the Phiomorpha (as restricted to Bathyergidae, Petromuridae, and Thryonomyidae) are sister taxa to the Caviomorpha. All modern hystricognath families are restricted to South America, Africa, or had a range that included Africa ( Hystricidae). New World monkeys appear to have colonized South America from Africa at a similar time. Caviomorphs went on to colonize the

West Indies The West Indies is an island subregion of the Americas, surrounded by the Atlantic Ocean, North Atlantic Ocean and the Caribbean Sea, which comprises 13 independent island country, island countries and 19 dependent territory, dependencies in thr ...

as far as the

Bahamas The Bahamas, officially the Commonwealth of The Bahamas, is an archipelagic and island country within the Lucayan Archipelago of the Atlantic Ocean. It contains 97 per cent of the archipelago's land area and 88 per cent of its population. ...

, reaching the

Greater Antilles The Greater Antilles is a grouping of the larger islands in the Caribbean Sea, including Cuba, Hispaniola, Puerto Rico, and Jamaica, together with Navassa Island and the Cayman Islands. Seven island states share the region of the Greater Antille ...

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

bison A bison (: bison) is a large bovine in the genus ''Bison'' (from Greek, meaning 'wild ox') within the tribe Bovini. Two extant taxon, extant and numerous extinction, extinct species are recognised. Of the two surviving species, the American ...

-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 tuco-tucos,

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 (scansorial), but others are exclusively arboreal. The hab ...

forms such as porcupines and certain spiny rats, running forms such as maras, and aquatic forms such as the

and

nutria The nutria () or coypu () (''Myocastor coypus'') is a herbivore, herbivorous, semiaquatic rodent from South America. Classified for a long time as the only member of the family Myocastoridae, ''Myocastor'' has since been included within Echimy ...

(Vassallo and Antenucci, 2015). Habitats include grasslands (maras), high mountains ( chinchillas and chinchilla rats), forest edges ( prehensile-tailed porcupines) and dense tropical forests ( pacas and acouchis). Although many species of caviomorphs have migrated into

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

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 land ...

, only a single living species, the North American porcupine, 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 is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

there.

Families

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

incertae sedis or is a term used for a taxonomy (biology), 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, uncertainty ...

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

s, and maras *** Ctenomyidae - tuco-tucos *** Cuniculidae - pacas *** Dasyproctidae - agoutis and acouchis *** Dinomyidae - pacarana ***† Eocardiidae ***†'' Guiomys'' ***† Neoepiblemidae ***†'' Scotamys'' **Superfamily Chinchilloidea *** Abrocomidae - chinchilla rats ***†'' Borikenomys'' - ''incertae sedis'' ***

Chinchillidae The family Chinchillidae is in the order Rodentia and consists of the chinchillas, the viscachas, and their fossil relatives. This family is restricted to southern and western South America, mostly living in mountainous regions of the Andes, ex ...

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

***†'' Caviocricetus'' - ''incertae sedis'' ***†'' Dicolpomys'' - ''incertae sedis'' *** Echimyidae - spiny rats, coypus, and hutias ***†'' Morenella'' - ''incertae sedis'' *** Octodontidae - degus and relatives ***†'' Plateomys'' - ''incertae sedis'' ***†'' Tainotherium'' Turvey, Grady & Rye, 2006 - ''incertae sedis'' Note that some changes to this taxonomy have been suggested by molecular studies. The Dinomyidae is now thought to belong to the Chinchilloidea rather than the Cavioidea, the Abrocomidae (according to some molecular work) and the Ctenomyidae 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