Caviomorpha is the rodent parvorder that unites all New World . 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 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 Abrocomidae, Capromyidae, and the capybara, and , , Dasyproctidae, Cuniculidae, Dinomyidae, Echimyidae, Erethizontidae, Myocastoridae and Octodontidae (Vassallo and Antenucci, 2015).
Origin
The first known rodent
fossils in
South America 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 or early
Oligocene. By the late
Oligocene, all superfamilies and most families of caviomorphs are present in the fossil record.
During this time, South America was isolated from all other . 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 of or driftwood.
The most common hypothesis suggests that the ancestor to all modern caviomorphs rafted across the Atlantic Ocean (then narrower) from Africa (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 Caribbean as far as the Bahamas, reaching the Greater Antilles by the early Oligocene.
Diversity
Caviomorph rodents underwent an explosive diversification upon arrival into South America. They managed to outcompete other animals in rodent-like
ecological niche such as certain
Ameridelphia. Retaining predominantly
herbivore diets, they expanded their sizes to encompass a range from
rat-sized
Echimyidae to the
bison-sized
Phoberomys. Their ecologies included burrowing
pocket gopher-like forms such as
,
arboreal forms such as porcupines and certain
Echimyidae, running forms such as maras, and
aquatic animal forms such as the
capybara and
nutria (Vassallo and Antenucci, 2015). Habitats include grasslands (maras), high mountains (
chinchillas and
), forest edges (prehensile-tailed porcupines) and dense tropical forests (
and
).
Although many species of caviomorphs have migrated into Central America since the Great American Interchange, 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 nutria has been introduced into North America and has proven a highly successful invasive species there.
Families
-
Parvorder Caviomorpha - New World hystricognaths
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
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.
See also
