The first known rodent fossilsinSouth 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.[citation needed]
During this time, South America was isolated from all other continents. 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 raftofmangrovesordriftwood.
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. In fact, until the discovery of the Laotian rock rat, all modern hystricognath families were 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.[1]
Caviomorphs went on to colonize the West Indies as far as the Bahamas, reaching the Greater Antilles by the early Oligocene.[2] This is commonly viewed as another example of oceanic dispersal,[3][4] although a role for a possible land bridge has also been considered.[2]
†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 may belong to the Octodontoidea, and the Hydrochaeridae may have evolved from within the Caviidae.[citation needed]
^ abVélez-Juarbe, J.; Martin, T.; Macphee, R. D. E.; Ortega-Ariza, D. (January 2014). "The earliest Caribbean rodents: Oligocene caviomorphs from Puerto Rico". Journal of Vertebrate Paleontology. 34 (1): 157–163. doi:10.1080/02724634.2013.789039. S2CID140178414.
^Hedges, S. Blair (November 1996). "Historical biogeography of West Indian vertebrates". Annual Review of Ecology and Systematics. 27 (1): 163–196. doi:10.1146/annurev.ecolsys.27.1.163.
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. ISBN0-231-11013-8
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.