forms such as maras, and aquatic forms such as the capybara and nutria (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 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 †Luribayomys - incertae sedis Superfamily Cavioidea Caviidae - cavies, capybaras, 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 - chinchillas and viscachas †Heptaxodontidae - giant hutias †Maquiamys - incertae sedis †Tsaphanomys - incertae sedis Superfamily Erethizontoidea Family Erethizontidae - New World porcupines Superfamily Octodontoidea †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 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).